Birds of paradise, biogeography and ecology in New Guinea: a review

Journal of Biogeography, 28, 893±925
Birds of paradise, biogeography and ecology
in New Guinea: a review
Michael Heads Science Faculty, University of Goroka, Goroka, Papua New Guinea
Abstract
Aim The paper reviews the biogeography and ecology of New Guinea using the birds of
paradise (Paradisaeidae) as an illustrative example.
Location New Guinea, the Moluccas, North-eastern Australia.
Methods Panbiogeographic analysis (Craw et al., 1999).
Results The family Paradisaeidae is interpreted as the main New Guinea vicariant in
Sibley & Ahlquist's (1990) Corvinae. It has evolved mainly on the New Guinea orogen,
extending, like the orogen, to the northern Moluccas and the Milne Bay islands, but not
present north of it on Karkar Island or New Britain. Within the orogen, Vogelkop ±
Huon Peninsula disjunctions (1500 km) occur between putative sister species in
Paradisaea, Astrapia and Parotia. Whatever taxonomic rank these af®nities warrant,
the biogeographic connection is inexplicable by `jump' dispersal from the mainland, but
is compatible with an accreted terrane model of New Guinea tectonics including massive
lateral strike-slip movement. This would also account for many aspects of distribution of
Paradisaeidae within the New Guinea highlands, and also disjunctions between Sulawesi
and the Bismarck Archipelago in the related genus Artamus.
Main conclusions Birds of paradise are sedentary forest dwellers with small home
ranges and are tolerant of disturbance. It is suggested that populations have been caught
in the dramatic geological uplift and downwarping of different parts of New Guinea.
This has led to fragmentation and juxtaposition of ranges, and determined the altitudinal
range of the taxa (including altitudinal `anomalies'). Areas of endemism in birds of
paradise include Quaternary volcanoes. In New Guinea large areas have eventually been
covered by lava ¯ows of different volcanic phases, but the living communities, including
local endemics, may remain more or less in situ by constantly colonizing younger ¯ows
from adjacent older ¯ows. In this way older life can `¯oat' on younger stratigraphy. At
least ®ve, possibly six, of the ®fteen genera in subfam. Paradisaeinae are known to occur
in mangrove. The ancestors of Paradisaeidae and other New Guinea bird families such as
Ptilonorhynchidae probably included birds of the mangrove, beach forest and coastal
hinterland which have been stranded in central Australia following marine transgressions
(Ptilonorhynchidae) and uplifted in New Guinea during the Tertiary orogeny
(Ptilonorhynchidae and Paradisaeidae).
Keywords
Paci®c, rainforest, biogeography, evolution, vicariance, dispersal, plate tectonics.
INTRODUCTION
The strikingly diverse birds of paradise, Paradisaeidae, have
been described as the most colourful avian group (Bock,
Correspondence: Science Faculty, University of Goroka, PO Box 1078
Goroka, Papua New Guinea. E-mail: mheads@dg.com.pg
1982). They inhabit New Guinea (®fteen genera, thirty-eight
species), the Moluccas (two genera, two species) and eastern
Australia (two genera, three species) (Fig. 1), but `all the
more extraordinary and magni®cent species' (Wallace, 1962
[1869]) are restricted to New Guinea. They have often been
the subject of biogeographical studies (Croizat, 1958;
Wallace, 1962 [1869]; Mayr, 1964 [1942]) and are used
here as a reference group in a review of biogeography and
Ó 2001 Blackwell Science Ltd

894 M. Heads
Again, this `discrepancy' or `paradox' has been explained
as resulting from the different means of dispersal (Mayr,
1953), but it seems more likely to be simply because of
different groups having different evolutionary centres;
angiosperms and insects both have major centres in the
Indian Ocean and Paci®c Ocean regions, whereas passerines
and mammals have major centres around the Indian and
Atlantic Oceans.
Figure 1 Distribution of Paradisaeidae, showing areas with ³ 10
species (stippled) and ³ 20 species (black) per 1° ´1° grid cell.
ecology in New Guinea. Some main aspects of distribution in
the birds of paradise are discussed ®rst.
BIOGEOGRAPHY
The major species concentrations in New Guinea of such
distinctive bird families as birds of paradise, bowerbirds
(Ptilonorhynchidae) and cassowaries (Casuariidae) renders
the absence there of major, widespread groups such as
trogons (Trogoniformes) and woodpeckers (Piciformes)
`almost mysterious' (Gilliard, 1969) and certainly worth
investigating. This presence and absence are sometimes
attributed to dispersal into New Guinea, or lack of it,
because of different means of dispersal in the respective taxa.
However, employing the usual concept of dispersal does
leave the patterns rather enigmatic. Instead, it is suggested
that these patterns of replacement are not caused by
`dispersal' as physical movement, but are the result of
vicariant evolution mediated by tectonic processes on prior
landscapes.
Different groups in New Guinea show af®nities with
different parts of the world. For example, plants and insects
there show many connections with Indo-Malaysia and there
are also many trans-tropical-Paci®c groups, whereas the
passerines and mammals show strong Australian connections.
(There are few trans-Paci®c ties in these groups ± the
New Zealand bat family Mystacinidae and South American
taxa, possible af®nities in marsupials, and possible af®nities
between the passerines Acanthisittidae of New Zealand and
suboscines in South America ± and these are in the far
south).
The New Guinea orogen
The birds of paradise are distributed rather evenly throughout
the folded and faulted mountain ranges of the spine of
New Guinea ± the New Guinea orogen (Figs 2, 4 & 29).
This mountainous belt was formerly regarded as the result of
a simple continent±island arc collision, but Pigram & Davies
(1987) gave a radical re-interpretation. They described the
orogen as consisting of a southern part (the Australian
craton), and a northern part made up of at least thirty-two
tectonostratigraphic terranes ± fault-bounded geological
provinces with independent histories from other terranes.
The New Guinea terranes, including intrusive and metamorphic
rocks, formed and sometimes amalgamated with
others some distance from their present position and
subsequently accreted to the craton margin. In the Vogelkop
accretion history involves mainly continental terranes. The
central Kemum terrane was detached from Gondwana by
the early Cretaceous and then had a history of movement
independent of the Australian craton until the Miocene. In
central New Guinea, the Sepik and Rouffaer terranes had
docked with the craton by the Late Oligocene, when the
New Guinea orogeny was initiated. In eastern Papua New
Guinea (PNG) several terranes of diverse origin amalgamated
in the Palaeogene (Early Eocene if this caused the
metamorphism of the proto-Owen Stanley terrane), and this
composite terrane then docked with the Australian craton in
the Miocene. Finally the Finisterre terrane was accreted to
the mainland at 3.0±3.7 Ma (Abbott et al., 1994), and rapid
uplift continues there. Probably New Britain will dock next.
Pigram & Davies (1987) discussed transcurrent movement
Figure 2 Geological map showing the Australian craton (grey), the
New Guinea orogen (between the heavy broken lines), and the
accreted New Guinea terranes (black). Blank areas on the map are
successor basins (simpli®ed from Pigram & Davies, 1987).
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Biogeography of birds of paradise 895
on faults, and suggested left-lateral offsets of up to 300 km
along the Ramu-Markham and the Bundi Fault Zones.
These new ideas in geology have been utilized in recent
studies on New Guinea biogeography (van Welzen et al.,
1992; Michaux, 1994; de Boer, 1995a; Turner, 1995; de
Boer & Duffels, 1996a,b; Polhemus, 1996; van Welzen,
1997; Polhemus & Polhemus, 1998; Heads, 1999) and in
this paper are compared with main aspects of distribution in
the Paradisaeidae. Locality maps are given in Figs 3 and 4.
Distributions of other birds cited are from Rand & Gilliard
(1967), Diamond (1972), Howard & Moore (1984) and
Beehler et al. (1986).
The Australia/New Guinea boundary
There is a great lowering of diversity in birds of paradise
between rainforest in New Guinea, which has up to twentyone
species in 1° by 1° squares, and rainforest in Queensland
with only one or two species per square (Heads, in press).
This pattern is seen in many groups, although the two
landmasses are almost completely linked physically and were
linked recently. The New Guinea biota is often seen as
derived from that of Australia (and Indonesia), but in fact
the two biotas differ greatly ± Good (1960, 1963) wrote
that this `extraordinary' difference is a `biogeographical
Figure 3 Locality map of New Guinea and
the Moluccas.
Figure 4 Locality map of the PNG Highlands,
showing land over 2400 m (stippled)
and land over 3600 m (black) and geological
terranes (Be ˆ Benabena, Bo ˆ Bowutu,
F ˆ Finisterre, J ˆ Jimi, Ma ˆ marum,
Me ˆ Menyamya, Sc ˆ Schrader,
Se ˆ Sepik, OS ˆ Owen Stanley).
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896 M. Heads
anomaly¼ nowhere else in the world is there, over a similar
distance, so great a difference in plant and animal life'.
Of the 906 `Australo-Papuan' bird species, 566 occur in
the New Guinea region and 531 in Australia (Keast, 1961),
although the latter is ten times greater in size. In a similar
way, tectonically complex Colombia has as many bird
species and subspecies as Brazil, although Brazil is 7.5 times
the area of Colombia (Dugand, 1948). Rallidae, Columbidae,
Psittacidae, Alcedinidae, Muscicapidae and Pachycephalidae
all have roughly 50% more genera in New Guinea
than in Queensland (Pratt, 1982), for example, there are
eight genera of parrots in New Guinea that are not in
Queensland. Likewise Ziegler (1982) wrote that it is
`surprising' just how few of the many indigenous New
Guinea mammals also occur in Australia. Conversely,
Ziegler observed that the bat family Megadermatidae is in
Australia and the Moluccas, but is `inexplicably' absent on
the New Guinea mainland.
The apparent absence of birds of paradise from most of
Australia and Indonesia is complemented by the concentration
there of the families Sibley & Ahlquist (1990) proposed
as the relatives of Paradisaeidae:
Artamidae (including Cracticidae and Grallinidae) (wood
swallows and butcherbirds) range from India to Australia
(most species), New Guinea, New Britain and Fiji.
Oriolidae (orioles) occur in Africa and Eurasia (Oriolus),
and Australia and PNG (Oriolus and Sphecotheres). New
Guinea has four species, but three are restricted to the south
coast and only one is widespread.
Campephagidae (cuckoo-shrikes; included with Oriolidae
by Sibley & Ahlquist) are distributed from Africa through
southern Asia to the Paci®c, with the main bulk of the
seventy-two species occurring west of New Guinea: Indonesia
west of Irian Jaya has twenty-seven species, New Guinea
®fteen, and Australia four.
The Corvidae (crows and jays; twenty-six genera) are
notably poorly represented in Australia (only ®ve species of
Corvus L.) and New Guinea (only three species of Corvus),
again indicating vicariance of a global ancestor. There are as
many as six genera of Corvidae in Indonesia.
The Callaeidae, a relic New Zealand group with three
monotypic genera, has often been placed with these families,
although Sibley & Ahlquist (1990) listed it as `incertae
sedis'.
In a similar, well-known example, the order Casuariiformes
comprises two families, Casuariidae (cassowaries)
mainly in New Guinea, and Dromaiidae (emus) in Australia.
Casuariidae has thirteen subspecies in New Guinea, three on
the Aru Islands, two on Japen Island and one on each of
Moluccas, New Britain, and northern Queensland. Fossils
are known from the Northern Territory. Dromaiidae has one
subspecies in each of NW and W Australia, SW Australia
and E Australia. There is no need to invoke any dispersal by
migration from Australia to New Guinea or vice versa to
explain the distribution of Paradisaeidae and Artamidae, or
Casuariidae and Dromaiidae, only simple vicariance around
a Torres Strait node (Heads, 1990). As Mayr (1953) noted:
`The independence of birds from habitat restrictions leads to
the remarkable phenomenon that the nearest relatives of
many birds of the central Australian brush savannas and
semi-deserts are found in the steaming lowland or the misty
mountain forest of New Guinea¼'.
Similarly, Taylor (1972) described Australia and New
Guinea as `separate evolutionary epicentres' for insects. The
two faunas are strongly autochthonous at species level, and
`Australia may be viewed as a producer of semi-arid adapted
species, New Guinea as a producer of moist-adapted
species'. Again, in this vicariance model there is no need
to invoke any dispersal by physical movement between
Australia and New Guinea to explain the main pattern.
Schodde & Calaby (1972) summarized the history of
biogeographical ideas on the region, writing that: `In recent
years [in fact since the time of Wallace and Matthew] there
has been an almost universal preoccupation with successive
waves of colonization to explain the present composition
and distribution of the whole Australo-Papuan land bird and
mammal fauna'. Schodde & Calaby were highly critical of
what they called this `simplistic' idea ± they suggested that it
has resulted from the `super®cial ease' with which immigration
can be invoked, and rests on the `shaky notion' that
biotas `must have moved because the continents could not'.
Instead, Schodde & Calaby cited data favouring the view
that the elements of the great arc of rainforest ¯ora and
fauna stretching through montane New Guinea and
E Australia are `old, autochthonous and co-inherited by
Australia and New Guinea' (cf. Webb et al., 1986).
The age of the profound Australia/New Guinea difference
is as controversial as the mode of its origin. Discussing the
tree family Sapindaceae, Turner (1995) wrote that the basal
split between taxa of E Australia and New Guinea `suggests
that the vicariance between these two regions may be older
than the often suggested period of post-Pleistocene rise in
sea-level¼'. Likewise, Zweifel (1985) saw `no reason' for
assuming that the initial vicariant event separating Australian
and New Guinea microhylid frogs occurred as recently
as the Pleistocene.
Torres Strait has traditionally been seen as either a bridge
for, or a barrier to dispersal, and has caused confusion as it
seems to be a `bridge' in some groups but a `barrier' in others
with similar ecology and means of dispersal. However, if
`dispersal' in the broadest sense of `any change in position' is
often a result of evolution, rather than physical movement,
the Torres Strait region is neither bridge nor barrier, but a
zone of biogeographical articulation and a centre of endemism
in its own right. In the same way, the Weyland
Mountains/Wissel Lakes in the west of New Guinea and the
Bismarck Fault Zone/Kratke Mountains in the east are not
bridges or barriers to dispersal for birds of paradise and
others, but represent areas around which allopatric evolution
has taken place. Similarly, birds of paradise and
bowerbirds (traditionally, but probably incorrectly, allied
with Paradisaeidae) are absent from the northern islands
fringing New Guinea (Biak, Manam, Karkar and the
Bismarck Archipelago), not because they are unable to ¯y
there, or were there and went extinct, but because their early
Tertiary ancestors did not live in the region. Instead, these
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Biogeography of birds of paradise 897
ancestors were concentrated on the lands and islands around
the craton margin which later became consolidated and
uplifted as the New Guinea orogen.
The different regions of the orogen are discussed next,
starting in the west.
The northern Moluccas
Terranes in the Moluccas may form a western extension of
the New Guinea orogen (Pigram & Davies, 1987). Birds of
paradise are represented in the northern Moluccas by two
unrelated monospeci®c genera, Lycocorax Bonaparte and
Semioptera Gray. This outpost of the family is `a bit of an
anomaly' for Frith & Beehler (1998) who explained it as
the result of overwater dispersal. However, although Frith
& Beehler (1998) wrote that Manucodia Boddaert, sister
group of Lycocorax, shows a `propensity for colonizing
islands', they immediately followed this by writing `We
hypothesize that Lycocorax is an island vicariant that
evolved from what was a widespread form that gave rise to
both Lycocorax and the genus Manucodia'. This second
view is supported here; there is no need to propose
`colonizing ¯ights' across modern geography by birds
already recognizable as Manucodia or Lycocorax. The
pre-Lycocorax + Manucodia widespread ancestral complex
may itself have `reached' the Moluccas, again, not by
physical movement but by vicariant evolution out of a
more or less global assemblage of pre-Corvidae/Paradaisaeidae/Artamidae/Oriolidae.
For the `very aberrant' Semioptera, Frith & Beehler (1998)
suggested that its weirdness and remarkable morphological
divergency are `deceptive', and might simply be the result of
`a very small founding population'. Nevertheless, according
to Frith & Beehler it has one set of characters linking it to
Ptiloris Swainson and another linking it to the Paradisaea
lineage. Stochastic `over-water dispersal', even with `founder
effects', is hardly likely to result in this arrangement ± it
would more likely result in Semioptera having one obvious
ancestor. It is simpler to account for the distribution by a
vicariance event in which the characters of a widespread
ancestral complex have been recombined to give Semioptera
in the Moluccas, and the Paradisaea and Ptiloris lineages
further east.
Despite their presence in the northern Moluccas, birds of
paradise are absent from the southern Moluccas. In fact the
fauna of the southern Moluccas is quite different from that
of the northern islands ± many widespread Indonesian
species occur on the southern islands without being in the
north, while many New Guinea groups such as Paradisaeidae
are represented in the northern islands only (White &
Bruce, 1986). Likewise, Michaux (1994) cited four mammal
species in the northern Moluccas and New Guinea, but not
in the southern Moluccas. Many taxa show differentiation
between the northern and southern Moluccas, in the
marsupials for example, Phalanger orientalis (Pallas) is in
the southern Moluccas (and Timor ± New Guinea), while
P. ornatus (Gray) and P. rothschildii Thomas are endemic in
the northern Moluccas (Flannery, 1994).
It is striking that there are only two genera of Paradisaeidae
in the Moluccas and that they are so distinctive, unlike
the Australian species which all have congeners in New
Guinea. Geological and biological evolution focused along
the New Guinea orogen may have been responsible.
The following birds, like the two endemic bird of paradise
genera, illustrate the status of the Moluccas as a biogeographically
independent centre:
In Megapodiidae, Megapodius wallacei Gray, sometimes
treated as a monotypic genus Eulipoa Ogilvie-Grant, is a
Moluccas endemic (Fig. 5), vicariant with Macrocephalon
MuÈ ller to the west and Aepypodius Salvadori in the east to
the Huon and Papuan Peninsulas.
Similarly, Ninox squamipila (Bonaparte) (Fig. 6) of the
Moluccas and Tanimbar Islands (with a disjunct race on
Christmas Island south of Java, 3000 km to the west) is
sandwiched between N. perversa Stresemann in the west and
N. theomacha Bonaparte to the east.
The cuckoo shrikes Coracina papuensis Gmelin,
C. parvula (Salvadori) and C. atriceps (MuÈ ller) (Campephagidae)
(Fig. 7) form a concentric series of species around
Halmahera (cf. Lycocorax enclosing Semioptera, which is
not on Morotai or Obi Islands).
The Moluccas are also interesting as a centre of absence.
Acanthizidae, for example, are widespread from Malaysia
and the Philippines to New Zealand (with Gerygone, etc.)
and while they closely surround the Moluccas, they do not
occur there (Ford, 1986). Other taxa present in both
Indonesia and New Guinea but not on the Moluccas include
the pigeon Gallicolumba, the tree Stemonurus Bl. and the
liane Phytocrene Wall. (Sleumer, 1971).
The western limit of birds of paradise on the Moluccas is
far from being an `anomaly' (Frith & Beehler, 1998). The
Moluccas show very clear faunistic links with New Guinea
and form the north-western limit of many New Guinea/
Australasian taxa. Casuariidae reach their western limit in
the southern Moluccas (Seram), while birds with a western
Figure 5 Three genera of Megapodiidae: Macrocephalon,
Megapodius wallacei Gray ( ˆ the monotypic Eulipoa): Moluccas,
Misol; and Aepypodius (east to the Saruwaged and Owen Stanley
Mountains).
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898 M. Heads
Figure 6 A sequence of three species in Ninox, a genus ranging
from Madagascar to New Zealand. N. perversa, N. squamipila (four
subspecies shown, a ®fth on Christmas Island indicated by arrow),
N. theomacha.
Figure 8 Aegothelidae (monogeneric) at its western limit. Aegotheles
crinifrons Halmahera and Bacan. The genus has six other species in
New Guinea (one of these also in Australia), one in New Caledonia,
and one (fossil) in New Zealand.
Figure 7 Coracina atriceps: N and S Moluccas, Coracina parvula:
Halmahera. C. papuensis: Misol I., Moluccas (melanolora), other
races in New Guinea, Solomons, northern Australia.
limit in the northern Moluccas, like the birds of paradise,
include the following taxa.
Aegothelidae (owlet nightjars) (Fig. 8) comprise eight
species of Australia, New Zealand (fossil), New Caledonia
and New Guinea, and range west to the northern Moluccas
where Aegotheles crinifrons Bonaparte is endemic.
Reinwardtoena Bonaparte (Columbidae) (Fig. 9) comprises
three species: one in the Solomons, one in New Britain
and R. reinwardtsi (Temminck) with races in New Guinea
and the western Papuan Islands, Biak and the Moluccas.
Tanysiptera Gray (Alcedinidae) (Fig. 10) reaches its western
limit with T. galatea (Gray) in New Guinea and the
Moluccas, and four other species on small islands around the
Vogelkop.
Gymnophaps Salvadori (Columbidae) (Fig. 11) comprises
three species: one in the Solomon Islands, G. albertisii
Figure 9 Reinwardtoena at its western limit. R. reinwardtsi has a
distribution resembling that of the Paradisaeidae, with subspecies in
New Guinea and Western Papuan Islands, Biak I. and the Moluccas.
Reinwardtoena has two other species, one in New Britain and
one in the Solomons.
Salvadori with subspecies in the Bismarck Archipelago, New
Guinea and northern Moluccas (Bacan only), and G. mada
Hartert in the southern Moluccas.
Charmosyna Wagler (Loriidae) (Fig. 12) ranges from Fiji
and New Caledonia west to New Guinea and the northern
and southern Moluccas.
Lorius Vigors (Loriidae) (Fig. 13) has four species in the
Bismarck Archipelago and Solomon Islands, one in New
Guinea, and the western limit of the genus is held by
L. garrulus (Linnaeus) in the northern Moluccas, and
L. domicellus (Linnaeus) in the southern Moluccas.
Alcedo (ˆ Ceyx, ˆ Alcyone) azureus (Latham) (Alcedinidae)
(Fig. 14) has three races in Australia, one each in
New Guinea, Tanimbar and Aru Islands and reaches its
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Biogeography of birds of paradise 899
Figure 10 Tanysiptera at its western limit. Tanysiptera galatea:
subspecies at: Rau I. (Moluccas), Morotai, Halmahera, Bacan,
Kayoa I. (Moluccas), Obi and Oblitau Is. Buru, S Moluccas, and ®ve
other races on the Western Papuan Islands and New Guinea. The
other western species are T. ellioti on Ko®au I., T. carolinae Schlegel
on Numfor I., T. riedellii Verreaux on Biak I, and I. hydrocharis in
S. New Guinea.
Figure 12 Charmosyna at its western limit: C. placentis with
subspecies on N Moluccas; S Moluccas, Aru Is., and New Guinea;
NW New Guinea; other subspecies occur in E New Guinea and
Bismarcks ± Solomons. C. toxopei is at Buru I. The genus ranges east
to Fiji and New Caledonia.
Figure 11 Gymnophaps at its western limit: G. mada S Moluccas,
and G. albertisii with subspecies on Bacan, and New Guinea and the
Bismarck Archipelago. The only other species in the genus occurs
in the Solomon Islands.
north-west limit with an endemic race in the northern
Moluccas. Similarly, A. pusilla (Temminck) has races in
New Guinea, Solomon Islands, Queensland and New
Guinea, with a western limit in the northern Moluccas.
Eos Wagler (Loriidae) (Fig. 15), with six species, occurs
only on the Moluccas and nearby islands (Biak, Tanimbar,
Kai and Talaud islands). The genus as such is absent from
mainland New Guinea, but is probably represented there by
Chalcopsitta Bonaparte and Pseudeos Peters.
Monarcha Vigors & Hors®eld (Myiagridae) (Fig. 16)
ranges through Australia, Solomon Islands, Bismarck Archipelago,
Yap Island and New Guinea, west to the approaches
of Sulawesi (genus limit shown in Fig. 16). Four of the
Figure 13 Lorius at its western limit: Lorius garrulus: subspecies on
Halmahera and Weda Is., Bacan and Obi, and Morotai.
L. domicellus: S Moluccas). L. lory: New Guinea wide. The genus
has four other species in the Bismarck Archipelago and Solomon
Islands.
Moluccan species are mapped here, none of these are found
on mainland New Guinea. Despite their geographical
insigni®cance some of the tiny islets in the region hold
striking endemism: Ko®au Island, NW of Misool Island, has
an endemic species, M. julienae Ripley. Tanysiptera ellioti
(Sharpe) (Fig. 10) is also endemic there. (Ko®au Island is
part of the Waigeo ophiolite terrane discussed below).
Nearby, Eos squamata attenua Ripley (Fig. 15) is endemic to
the even smaller Schildpad Islands north off Misool;
Zosterops chloris (below) is also on Schildpad Islands but
not Misool.
At lower taxonomic levels, species (e.g. Myzomela obscura
Gould) and subspecies (e.g. Aplonis m. metallica Temminck,
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900 M. Heads
Figure 14 Ceyx (ˆ Alcedo, ˆ Alcyone) azureus at its western limit:
subspecies in N Moluccas, Tanimbar, Aru Is., Western Papuan Is.
and New Guinea. There are three other races in NES Australia and
Tasmania. C. pusillus also ranges from Solomons, Queensland west
through New Guinea to Halmahera and Obi (C. p. halmaherae).
Figure 16 Monarcha at its north-western limit (hatched line).
Monarcha pileatus Salvadori, with subspecies on Halmahera, Buru,
and Tanimbar. M. trivirgatus (Temminck), also disjunct in
Queensland and the Louisiade Is. (arrow), M. julienae (Ko®au), and
M. brehmii (Schlegel) (Misool, Biak I.) with af®nities to Manus and
Bismarck Archipelago species (arrow).
Figure 15 The six species of Eos: E. histrio P.L.S.MuÈ ller (Talaud
Is.), E. squamata (Boddaert): Obi (obiensis), Maju I. (atrocaerulea),
N Moluccas (riciniata), Western Papuan Is. (nominate). E. cyanogenia
Bonaparte (Geelvink Bay islands), E. reticulata (S.Muller):
Tanimbar and Kai Is., E. bornea Linnaeus (S Moluccas, Kai Is.),
E. semilarvata Bonaparte (Seram). The related Chalcopsitta and
Pseudeos occur on mainland New Guinea.
Artamus leucorhynchus leucopygialis Gould) also have a NE
Australia ± New Guinea ± Moluccas distribution more or less
the same as that of Paradisaeidae.
In beetles, Chrysomelidae subfamily Hispinae has twentyone
genera in New Guinea, fourteen of which range west
only to the Moluccas (Gressitt, 1982a). Likewise in frogs,
Microhylidae subfamily Asterophryinae is endemic to New
Guinea and the Moluccas (Richards et al., 2000), and the
genus Nyctimestes Stejneger (Hylidae) has a range practically
identical to that of the birds of paradise: New Guinea
(most species), the Milne Bay islands, northern Australia,
and the northern Moluccas (Zweifel, 1958; Tyler, 1968).
The lizard genera Eugongylus Fitzinger and Carlia Gray also
range through New Guinea west to the Moluccas (Greer,
1974).
Many characteristic plants of Australasian and Melanesian
rainforests also have a north-western limit at the
Moluccas. For example, in the seed plants, Himatandraceae
(comprising Galbulimima F.M. Bail.) is in NE Australia,
New Guinea, and the Moluccas (Croft, 1978) like the
Paradisaeidae. A group of four genera in Cunoniaceae:
Spiraeanthemum A. Gray (including Acsmithia Hoogland),
Gillbeea F. Muell., Aistopetalum Schlechter and Brunellia
Ruiz & Pav., forms a basal clade in the family, sister group
to the rest, and occurs in Central America, Polynesia, NE
Queensland, New Guinea and the Moluccas (Hufford &
Dickison, 1992). Other plant taxa which break off range
westward at the Moluccas include the fern Leptopteris Presl
(van Balgooy, 1966a,b), the conifers Decussocarpus de
Laub. sect. Decussocarpus (de Laubenfels, 1984) and Papuacedrus
Li (Li, 1953), the monocots Pandanus sect.
Maysops St John (Stone, 1992), Cominsia Hemsl., Helmholtzia
F. Muell. (Johns & Hay, 1981), Drymophloeus Zipp.
(Zona, 1999), Gulubia Becc. (Drans®eld, 1993), Glossorhyncha
Ridley (Smith, 1979±1996), and Pterostylis R.Br.
(de Vogel, 1975a), and the dicots Levieria Becc. (Philipson,
1986), Pararistolochia Hutch. & Dalz. (re-appearing in
Africa) (Parsons, 1996), Rhyticaryum Becc., Polyporandra
Becc. (Sleumer, 1971), Hollrungia K. Schum. (de Wilde,
1975), Hugonia sect. Durandea Planch. (van Balgooy,
1993), Dubouzetia Pancher ex Brongn. & Gris (Coode,
1987), Schleinitzia Warb. (de Vogel, 1975b; as Prosopis
insularum (Guill.) Bret.), Archidendron ser. Stipulatae
(Mohl) Nielsen, A. ser. Pendulosae (Mohl) Nielsen, and
A. ser. Morolobiae (Kosterm.) Nielsen (Nielsen et al., 1984),
Pullea Schlechter (Hoogland, 1979; cf. Hufford & Dickison,
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Biogeography of birds of paradise 901
1992), Flindersia R.Br. (Roos, 1984), Jagera Blume, Sarcopteryx
Radlk., Sarcotoechia Radlk. (the last three from
Adema et al., 1994), Burckella Pierre (Pennington, 1991),
Eucalyptopsis White (White, 1951; Johns, 1980), Lindsayomyrtus
Hyland & Steen. (Hyland & van Steenis, 1973),
Octamyrtus Diels (Scott, 1979a), Mastixiodendron Melchior,
Cyclophyllum Hook.f. (Smith, 1979±1996), Tecomanthe
Baillon (van Steenis, 1977), and such characteristic, widespread
New Guinea species as Schuurmansia henningsii
K.Sch. (Kanis, 1978).
Like most important centres of endemism, the Moluccas
have several far-¯ung biogeographical af®nities. For example,
four species of Accipiter (Accipitridae) show disjunct
connections between the Moluccas and New Britain which
do not involve mainland New Guinea: A. erythrauchen G.R.
Gray (Fig. 17) of the northern Moluccas is similar to
A. brachyurus (Ramsay) of New Britain, just as A. henicogrammus
(G.R. Gray) of the northern Moluccas is related to
A. luteoschistaceus Rothschild & Hartert of New Britain
(Wattel, 1973). The butter¯y Eurema candida is also
disjunct between Moluccas/Timor and the Bismarck Archipelago/Solomon
Islands (Parsons, 1999). Similarly, the fern
genus Christensenia Maxon. is disjunct between west
Malesia/Moluccas and New Ireland ± Solomons (Johns &
Bellamy, 1981). Also in ferns the closely related Christella
perpubescens (Alston) Holttum group has one species in
each of the following: the Moluccas; Waigeo Island and
disjunct in the Solomons; Biak island; and New Ireland, all
on limestone (Holttum, 1976, 1981). In the Araceae,
Spathiphyllum commutatum Schott (Araceae) occurs in the
Philippines, Palau, Sulawesi, and the Moluccas, and is
disjunct from there to New Britain and Bougainville, being
absent from mainland New Guinea. It is replaced in Manus,
New Ireland and SE New Guinea by two further species in
the genus, the remainder are all in tropical America (van
Steenis, 1961; Hay, 1990). Spathiphyllum is replaced on
mainland New Guinea outside the Papuan Peninsula by the
more or less closely allied Holochlamys Engl.
This Moluccas ± New Britain connection is related to
similar disjunctions. For example, Ninox connivens Latham
(Fig. 17) is in the northern Moluccas, eastern PNG and
Australia, bypassing Irian Jaya, and a similar range (northern
Moluccas; Sepik) is held by the tree Dictyoneura
acuminata Blume ssp. acuminata, with the gap in Irian Jaya
®lled by D. acuminata ssp. microcarpa J. Dijk (van Dijk in
Adema et al., 1994). Other examples were noted by
Michaux (1994). An even greater disjunction across the
north of New Guinea is shown in conifers. Dacrydium
magnum de Laub. occurs only in the northern Moluccas
(Obi), and on islands east of New Guinea ± the Louisiades
(Sudest Island) and the Solomon Islands (de Laubenfels,
1988), and Podocarpus spathoides de Laub. has a very
similar distribution: northern Moluccas (Morotai), disjunct
to the Louisiades (Rossel) and Solomon Islands, with an
additional disjunct record in the west on the Malay
Peninsula (Mount Ophir ˆ Gunong Ledang).
In many taxa the Moluccas populations are involved with
those of the Aru Islands, with the af®nity skirting New
Guinea to the south-west and not present on the mainland.
Three examples are illustrated:
Hemiprocne mystacea con®rmata Stresemann (Fig. 18) is
on the Moluccas and Aru Islands; other races occur in New
Guinea, Bismarck Archipelago and the Solomon Islands.
Zosterops chloris Bonaparte (Fig. 19) ranges on the Banda
Sea islands, islets off SE Borneo, and also on the Torres Strait
islands, but is not on the New Guinea mainland. Z. c. chloris
is restricted to the Moluccas, Kai and Aru Islands.
Z. atriceps Gray is endemic in the northern Moluccas.
Pachycephala phaionota (Bonaparte) (Fig. 20) surrounds
the Vogelkop to the west, north and south: it is on the
northern Moluccas, Aru Islands, the western Papuan Islands
and also small islands in Geelvink Bay.
Figure 17 Accipiter erythrauchen G.R.Gray: Bacan, Halmahera,
Morotai, Obi (nominate), Seram, Buru (ceramensis (Schlegel)). This
species is similar to A. brachyurus of New Britain (arrow).
A. henicogrammus: Bacan, Halmahera, Morotai; related to
A. luteoschistaceus of New Britain. Ninox connivens, disjunct in E
New Guinea (east of Merauke and Karkar Island) and Australia.
Figure 18 Hemiprocne coronata (Sulawesi), H. mystacea with
subspecies on Moluccas and Aru Is., and in New Guinea, Bismarck
Archipelago, Solomon Islands.
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902 M. Heads
Figure 19 Zosterops atriceps (hatched) subspecies on Morotai,
Halmahera, and Bacan. Z chloris has subspecies (solid line) on Aru,
Kai, Seram, Schildpad, Halmahera; S Moluccas, Tanimbar, Torres
Srait Is. (albiventris), and others around Sulawesi, Lombok and
islands off SE Borneo.
Figure 21 The distribution of Aquilaria ®laria (Thymelaeaceae).
Figure 20 Pachycephala phaionota, with two subspecies: one on
Aru Is., N Moluccas, Western Papuan Islands and Geelvink Bay
islets, the other endemic to Majau I. (N Moluccas). The genus ranges
north to Thailand.
The Moluccas have an important biogeographical connection
to the south, for example Lichmera Cabanis reaches
its northern limit in the Moluccas. To the north, the
Moluccas link New Guinea with the Philippines. Examples
are Amaurornis olivaceus (Meyen) and the tree Aquilaria
®laria (Oken) Merr. (Ding Hou, 1960; now also known
from the Sepik region) (Fig. 21).
Finally, the northern Moluccas are an important eastern
boundary for many Indian Ocean groups, such as the land
snail family Clausiliideae (Szekeres, 1980), the sylvine
warbler Bradypterus Swainson (Africa ± northern Moluccas),
the bat family Megadermatidae (Africa ± northern
Moluccas) and the palm subtribe Oncospermatinae J.D.
Hooker (Uhl & Drans®eld, 1987; map 43) (Seychelles has
four genera, Sri Lanka ± northern Moluccas has one genus).
Craw et al. (1999, Fig. 4.4) mapped vicariant butter¯y
genera in, respectively, SE Asia east to Sulawesi, and the
Moluccas east to Australasia.
Summarizing, the biogeographical boundary, or node,
between Sulawesi and the Moluccas (`Weber's line') may not
be as well-known as its over-famous neighbour, the break
between Sulawesi and Borneo (`Wallace's line'), but it is
probably of similar signi®cance. As shown, a break between
the Moluccas and Sulawesi occurs in many plants and
animals, and this same break in Paradisaeidae cannot be
interpreted as an anomaly. The northern Moluccas have
several different standard biogeographical connections with
north and south New Guinea, recalling the different character
recombinations in Semioptera.
De Boer (1995a) wrote that the cicadas of the Moluccas
show ®ve distinct patterns of distribution, each indicating
different relationships between parts of the Moluccas and
different areas. Like Paradisaeidae and the other birds
mapped above, the cicadas Cosmopsaltria StaÊl, Diceropyga
StaÊl, Aedeastria de Boer (Fig. 22), Gymnotympana StaÊl
(Fig. 23) and Baeturia StaÊl are all mainly in New Guinea,
but each has a few species in NE Queensland and outlying
endemics in the Moluccas. Discussing these genera, de Boer
(1995a) cited three volcanic island arc systems in the the
West Paci®c, one of which, the Halmahera arc, comprises
eastern Mindanao (Philippines), the northern Moluccas and
Waigeo Island, and possibly connects with the Mariana and
Palau/Yap arcs. The Halmahera arc formed far to the east of
its present position on a fracture of the Paci®c plate ± it
might have ended close to the Papuan Peninsula. Since the
early or middle Miocene the arc has swept 2000 km
westwards past the north-western edge of New Guinea into
the Moluccas region (Daly et al., 1991; Honza, 1991). The
geology of the northern Moluccas region is highly complex
and controversial; one interpretation is shown in Fig. 24.
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Biogeography of birds of paradise 903
arcs from eastern PNG. This would also account for the
Moluccas ± New Britain/NE PNG disjunctions seen in
Accipiter, Ninox and others.
South of Halmahera, but still in the northern Moluccas,
Obi Island (where Lycocorax pyrrhopterus obiensis Bernstein
is endemic) and Bacan Island (where Semioptera
w. wallacii Gould is endemic) comprise a separate microcontinent
distinct from Halmahera. The origin of the
southern Moluccas (Buru and Seram) is still subject to
controversy, but the microcontinent they form is of Australian
origin (de Boer, 1995a) and is quite distinct from that of
the northern Moluccas.
Figure 22 The distribution of Aedeastria (Homoptera) species.
Figure 23 The distribution of Gymnotympana (Homoptera)
species.
Western Papuan Islands
Seven species of birds of paradise are indigenous to the
Western Papuan Islands, lying between the New Guinea
mainland and the Moluccas. Several mainland species occur
on Salawati and Misool and Manucodia ranges to Gebe
Island. Cicinnurus respublica (Bonaparte) and Paradisaea
rubra Daudin are striking species both endemic to Waigeo
and Batanta; birds endemic to these islands are discussed
below as examples of ophiolite terrane endemism. In stark
contrast, Zosterops Vigors & Hors®eld, supposedly a lover
of small islands, is `strangely enough' (Rand & Gilliard,
1967) totally absent from Waigeo, Batanta, Misool and
Salawati, although Z. chloris extends right up to the
approaches of Misool on the tiny Schildpad Islands
(Fig. 19). This absence of Zosterops from Misool and the
others is indeed striking, and inexplicable by dispersal as
movement, as the genus has ®ve species in the Moluccas,
nine in New Guinea, and there is an endemic genus of
Zosteropidae on each of Seram and Buru. The Western
Papuan Islands also form an eastern limit for widespread
Indian Ocean groups such as Strophanthus DC. (Apocynaceae):
West Africa to western Papuan Islands (Beentje,
1982).
Figure 24 Geology of the Moluccas region. Tectonic elements
(subduction zones, faults, volcanic arcs) as heavy lines, arrows
indicate motion on strike-slip faults (from Axelrod & Raven, 1982
after Hamilton, 1977).
de Boer (1995a,b) and de Boer & Duffels (1996a,b)
proposed that the north Moluccan cicadas are derived from
ancestral forms which travelled on fragments of volcanic
The Vogelkop
The Vogelkop, like the Huon and Papuan Peninsulas and
major biogeographical nodes in general, is an important
centre of biological endemism, absence and disjunction. The
Kemum terrane in the central Vogelkop originated as a
detached portion of Gondwana (Pigram & Davies, 1987)
and other component terranes of the Vogelkop are also of
interest. The Arfak Mountains are a major centre of
endemism, for example, four out of twenty-two New Guinea
species of Rapanea Aubl. (Myrsinaceae) are endemic there,
at the Anggi Lakes (Sleumer, 1986).
In the birds of paradise Astrapia nigra (Gmelin) is
restricted to the Arfak and Tamrau Mountains, and its
af®nities are with the Huon Peninsula species A. rothschildi
Foerster, 1500 km to the east (Fig. 25).
Similarly, within the black, blue-eyed Parotia species
(Fig. 26), P. se®lata of the Vogelkop and nearby Wandammen
Peninsulas may well be the sister species of P. wahnesi
of the Huon Penisula and the Adelbert Mountains. Both
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904 M. Heads
Figure 25 The two related species Astrapia nigra and A. rothschildi.
Figure 26 The black, blue-eyed Parotia species, and P. carolae.
Figure 27 Paradisaea subgen. Paradisaea. The three species with
`decomposed' ¯ank plumes ± P. rubra, P. guilielmi and P. decora.
The ®rst two are a related pair with green forecrown and reddishbrown
iris.
share a longer tail and behavioural similarities (E. Scholes,
pers. comm., September 2000).
Likewise, in their cladogram Frith & Beehler (1998) have
Paradisaea rubra Daudin, of Waigeo and Batanta Islands
(ophiolite terrane) just off the Vogelkop, as the sister species
of P. guilielmi Cabanis, of the Huon Peninsula mountains
(Fig. 27). Neither Frith & Beehler (1998) nor Gilliard (1969)
give any characters linking these two but they do seem
related: in the males of both, but in no other species, the oilgreen
throat colouration extends above the eye to cover the
front of the crown, and the eye is reddish-brown, not yellow.
In addition the tail wires (central rectrices) are longer
relative to body size in these two species. Finally, P. rubra
and P. guilielmi have the outermost primaries with no
emargination on the inner vane, unlike the other species.
Whatever rank this grouping warrants, the biogeographical
af®nity is of great interest and could be investigated further.
Frith & Beehler's (1998) only comment is that the two
species are each an `aberrant sister form' of the main
Paradisaea clade. This interpretation ®ts with the theory
postulating colonization of the offshore islands and coastal
ranges from the central ranges, but it is not consistent with
the cladogram, in which P. rubra and P. guilielmi together
form the sister group to the rest of Paradisaea subgen.
Paradisaea. The invasion theory would predict the two
outlying species to be separately related to the central group
of species, as implied in Frith & Beehler's comments. The
mutual af®nity of the two species is inexplicable under the
dispersal theory, but is easily compatible with an accreted
terrane model of New Guinea biogeography (Heads, 1999),
or indeed any model that accepts geological change, such as
strike-slip movement, as relevant to biological distribution.
In a similar example, Melipotes (Meliphagidae) comprises
three species: the black-breasted M. gymnops Sclater (Arfak,
Tamrau and Wandammen Mountains) and M. ater Roths
child & Hartert (Huon Peninsula mountains), separated by
M. fumigatus Meyer with a slaty lower breast (Rand &
Gilliard, 1967). Melipotes' putative sister group is another
frugivore, Macgregoria De Vis (Cracraft & Feinstein, 2000)
(formerly considered a bird of paradise), which itself shows a
disjunction between the Star Mountains and the Papuan
Peninsula.
Other Vogelkop disjunctions involve taxa known only
from there and western PNG, especially the Karius Range ±
Muller Range area. Examples in the birds of paradise are the
black, blue-eyed Parotia species (with the gap ®lled by
P. carolae Meyer) (Fig. 26), and the long-tailed Astrapia
species (with the gap ®lled by A. splendidissima Rothschild)
(Fig. 28). Drepanornis albertisi cervinicauda Sclater has a
very similar disjunction: Weyland Mountains ± Doma Peaks.
Frith & Beehler (1998) downplay these Vogelkop disjunctions
± in the Astrapia species the `curious' plumage
similarities may represent symplesiomorphies (no evidence
is given), the disjunction in Paradisaea is hardly mentioned,
in the black parotias the disjunct forms are `certainly' sister
taxa but the mode of their differentiation is `unclear', and
in Drepanornis the distribution is `peculiar in the extreme'
and may be a taxonomic `artefact'. Nevertheless, the
Vogelkop ± Huon Peninsula disjunction and related patterns
occur in many other animals and plants and are
probably important clues to the history of northern New
Guinea and their biota.
The Vogelkop ± Huon disjunction is seen in invertebrates
such as the spiders Argiope aemula (Walckenaer) and
A. appensa (Walckenaer) (Levi, 1983) and in plants such
as the following:
Hartleya Sleum. (Vogelkop, disjunct south of Lae at
Mounts Shungol and Kaindi) (Sleumer, 1971),
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Biogeography of birds of paradise 905
Sphenostemon arfakensis (Gibbs) Steen. & Erdtman.
Vogelkop (Arfak Mountains), closest to S. lobosporus
(F.v.M.) L.S. Smith of Jimi Valley, Milne Bay and
Queensland (van Steenis, 1986),
Mammea odorata (Raf.) Kosterm. Vogelkop, disjunct at
Madang and points east (Stevens, 1974b).
Figure 28 The long-tailed Astrapia species, and A. splendidissima.
Picrasma Blume (van Balgooy, 1966a, b),
Koompassia Maingay ex Benth. (Verdcourt, 1979),
Sycopsis Oliver (Vink, 1957),
Lycianthes subg. Polymeris sect. Asiomelanesia Bitt.
(Symon, 1984),
Aglaia teysmanniana, A. elaeagnoidea (Pannell, 1992),
Aglaonema marantifolium Bl. (Araceae) is disjunct
between Moluccas/Kai Is./Aru Is./Vogelkop, and Madang/Huon
Peninsula/Bulolo (Nicholson, 1969).
Very similar disjunctions are seen in the following
plants:
Soulamea Lam. Vogelkop, disjunct at Madang (van
Steenis, 1961),
Sambucus L. Vogelkop and Wissel Lakes, disjunct on the
Huon Peninsula (van Steenis, 1978),
Illigera Bl. Vogelkop, disjunct at the lower Ramu (Croft,
1981),
Archidendron ser. Pendulosae (Mohl.) Nielsen. Vogelkop,
disjunct at Madang and the Papuan Peninsula
(Nielsen et al., 1984),
Alyxia subser. Clusiaceae Markgr. Vogelkop and Meos
Num Island in Geelvink Bay, disjunct at Bulolo (Markgraf,
1977),
Amyema queenslandica (Blakely) Danser. Vogelkop,
disjunct at Mount Kaindi and points south-east (Barlow,
1992),
Rhododendron erosipetalum J.J. Sm. Vogelkop, closest
to R. detznerianum Sleum. of Garaina and Goilala
(Sleumer, 1973),
Xanthophytum Reinw. Vogelkop, disjunct at Morobe
and the Papuan Peninsula (Axelius, 1990),
Romnalda P.F. Stevens. Japen Island, disjunct at the
southern Morobe coast (Stevens, 1978),
Rapanea minutifolia Knoester, Wijn & Sleumer. Vogelkop,
disjunct at Mount Kaindi, Mount Amungwiwa
and Milne Bay (Sleumer, 1986),
Alocasia pyrospatha A. Hay. Vogelkop, Misool I.,
Rouffaer R. ( ˆ Tariku R., the western tributary of
Mamberamo R.) and disjunct at Lae (Hay & Wise,
1991),
Xanthomyrtus angustifolia A.J. Scott. Sulawesi,
Vogelkop, Mount Kaindi, and (possibly) Normanby
Island (Scott, 1979b),
In many cases the gap is ®lled by a related taxon, for
example the gap in Mammea odorata is at least partly ®lled
by M. papuana (Laut.) Kosterm. in East Sepik (Stevens,
1974b). Likewise, Jansen & Ridsdale (1983) described a
series of Dolicholobium A. Gray. comprising eleven species
at, respectively: Japen Island; Idenburg River; Sepik area
(two species); Huon Peninsula/Port Moresby; Sudest Island;
Woodlark/Misima Islands; Rossel Island; Bougainville; Solomon
Islands (two species). The distribution basically skirts
the north coast, but is not a simple cline; as Jansen &
Ridsdale exclaimed, `The two species from the Sepik area
[in the centre of the range] are the most different ones within
this series!'. This gives a disjunction between Idenburg River
and Huon Peninsula similar to that of Alocasia pyrospatha
(above).
It is probably signi®cant that while the Tamrau terrane is
unlike any of the other terranes in western Irian Jaya, there
are similar sequences with mid-Miocene intermediate volcanics
on the northern ¯ank of the central ranges in eastern
Irian Jaya and PNG (Pigram & Davies, 1987). This recalls
the proposed massive westward movement of the Halmahera
arc cited above.
As indicated, a frequent variation of the Vogelkop ± Huon
disconnecton is a Vogelkop ± Papuan Peninsula disjunction.
For example, Melanocharis arfakiana (Finsch) (Dicaeidae) is
known only from Vogelkop (Arfak Mountains) and north of
Port Moresby (Matsika, halfway between Kairuku and
Mount Albert Edward), with sight records on the nearby
Kokoda trail. Zosterops minor tenuifrons (Greenway) is in
the Vogelkop (Tamrau Mountains) and also SE New Guinea
(Herzog Mountains to Hydrographer's Mountains) (Rand &
Gilliard, 1967). Diamond (1972) referred to ®ve `drop-out'
bird species which are present on the Vogelkop and in PNG
but are not in the Irian Jaya mountains. Like the alpine
`drop-outs' considered below, these disjunctions can be
explained by movement and accretion of terranes rather than
extinction of central populations.
A further related Vogelkop disjunction is illustrated by
Araliaceae, in which Frodin (1998) recorded Osmoxylon
Boerl. disjunct between the Vogelkop and the Bismarck
Archipelago, and Gastonia serratifolia (Miq.) Philipson disjunct
between the Vogelkop and the central Solomons. Frodin
concluded that these patterns possibly relate to movement
along the Sorong Fault, a strike-slip zone initiated 20 Ma.
It was shown above that the tie between the greenheaded,
red-eyed paradisaeas (P. rubra on Western Papuan
Islands, off the Vogelkop, and P. guilielmi of Huon
Peninsula) represents a standard biogeographical connection.
Paradisaea decora of the D'Entrecasteaux islands
shares `wispy' or `decomposed' ¯ank-plumes with these
two species, and perhaps the resultant northern track is also
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906 M. Heads
a real phenomenon. Although many distributions are
disjunct between Karkar and nearby islands and the
D'Entrecasteaux islands, or between Huon Peninsula and
the Milne Bay mainland, there does not seem to be a direct
biogeographical connection between Huon Peninsula and
the D'Entrecasteaux islands. However, there is one between
the D'Entrecasteaux region and the Vogelkop (2100 km).
For example Archidendron tenuiracemosum Kanehira &
Hatusima (Moluccas, Vogelkop) is a `very close' sister
species of A. hooglandii Verdcourt (D'Entrecasteaux)
(Nielsen et al., 1984), Salacia forsteniana Miq. is disjunct
between the Moluccas/Waigeo and Normanby Island (Ding
Hou, 1964), a group of four species in Philipson's (1986)
key to Kibara Endl. (under couplet 8b) are only in the
Vogelkop, and the D'Entrecasteaux and Louisiade islands,
and the conifers disjunct between the Moluccaas and the
Louisiades cited above have a similar pattern. This gives
two standard links, one between the Vogelkop and Huon
Peninsulas, and the other between the Vogelkop and the
D'Entrecasteaux ± Louisiade islands.
De Boer & Duffels (1996a,b) used terrane re-alignments,
including a proposed eastern origin of Vogelkop terranes,
in a detailed rationalization of similar vast disjunctions
(e.g. Vogelkop ± Solomon Islands) in cicadas, which also
accounts for the Paradisaea species discussed here.
Weyland Mountains and Wissel Lakes
This region lies right on the margin of the craton and forms
an important east/west boundary for many birds of paradise.
Montane examples include Pteridophora, a lowland example
is Paradisaea apoda Linnaeus (ranging west to the
southern foothills of the Weyland mountains known as
the Charles Louis Mountains). As well as being a boundary,
the region is an important centre of endemism: Parotia c.
carolae Meyer is only at the Wissel Lakes, and Astrapia s.
splendidissima Rothschild is endemic to the range: Wissel
Lakes ± Weyland Mountains. The Parastacidae are a
southern hemisphere family of large freshwater crustaceans
with thirteen species in New Guinea, eight of which are
endemic to the Wissel Lakes (Holthuis, 1982) (Recently
Hansen & Richardson, 2000; suggested that genera in this
family are at least 90 Ma old, and the species `far more
ancient than formerly believed'.). The Weyland Mountains
are also a centre of disjunction: for example Drepanornis
albertisi cervinicauda is disjunct between there and the
Doma Peaks in western PNG.
Snow Mountains
The main Irian Jaya ranges from the Weyland Mountains to
the Star Mountains include the highest peaks in the New
Guinea orogen (Mt Carstensz ˆ Mt Sukarno ˆ Mt Irian
ˆ Mt Jaya, 5039 m) and also have the most distinctive and
numerous endemic birds. There are two endemic, monotypic
genera, Anurophasis van Oort (Phasianidae) and Androphobus
Hartert & Paludan (Orthonychidae), and four other
endemic species in Petroica Swainson, Pachycephala Vigors,
Lonchura Sykes and Aegotheles Vigors & Hors®eld. Six
species are shared only with the Vogelkop and are not in
eastern New Guinea.
The whole of mainland Irian Jaya has thirty-two endemic
bird species (Mack, 2000), compared with only ®fteen on the
PNG mainland (Beehler, 1993). However, this difference
does not result from a simple dropping-out of taxa from west
to east. Several groups, including birds of paradise, are more
diverse on the eastern side of the island: thirty three species
of birds of paradise are known from PNG, twenty-eight (that
is, 15% fewer) from Irian Jaya, and there is also less
subspeci®c differentiation on the western side of the island
(Croizat, 1958). This eastern bias is shown clearly in the
genus Paradisaea Linnaeus and in plants such as Parahebe
W.R.B. Oliver (Heads, 1994), but its origin is unknown. It
may be related to the greater number of accreted terranes
and more volcanic activity in PNG than in Irian Jaya (except
the Vogelkop). The groups massing in eastern New Guinea
are often `Australo-Papuan' taxa such as the Paradisaeidae
or Parahebe, and dominate the PNG biota; of the ®fteen
PNG mainland endemics, seven are birds of paradise and
two are bowerbirds.
Papua New Guinea Highlands
Diamond (1972) observed that the highly localized or
`patchy' distributions of many montane New Guinea birds
comes initially as a surprise to some temperate zone
ornithologists, whose ®rst reaction may be to dismiss the
phenomenon with a trivial explanation such as the patchiness
being the result of inadequate exploration or highly
specialized habitats. However, `enough is known about
distribution in most cases, and about habits in many cases,
to dismiss these explanations'. Diamond (1972, 1973) cited
several birds, including Macgregoria, under the heading
`drop-outs in the eastern (i.e. PNG) highlands'. He wrote:
`The central dividing range of New Guinea provides an
uninterrupted expanse of montane forest for 1600 km.
Nevertheless, eighteen montane bird species that would
otherwise be uniformly distributed have a distributional gap
of several hundred kilometers somewhere along the Central
range'. These taxa sometimes have the gap ®lled by a closely
related taxon, but often not. Diamond suggested that the
drop-outs were explained by local extinction, although Pratt
(1982) observed that what factors caused the local extinction
in the ®rst place `are not altogether clear'. It seems just as
likely that the distributions are explained by the species
`dropping in', through having been present on some accreting
terranes and having always been absent from others.
Large scale right-lateral and left-lateral movements have
been proposed along many New Guinea faults and may have
caused disjunctions; Diamond (1986) noted that many New
Guinea birds are `extremely sedentary'.
Similarly, the mountains of the Papuan Peninsula, SE New
Guinea (mainly Owen Stanley and Bowutu terranes) also
`inexplicably' (Diamond, 1972) lack several montane birds
of paradise that are present throughout the rest of the New
Guinea cordillera (Loboparadisaea Rothschild, Pteridophora
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Biogeography of birds of paradise 907
Meyer, Paradigalla Lesson, and others discussed below). The
north coast here also lacks several otherwise widespread
lowland species, although it is a centre of endemism for
other taxa. Again, these standard patterns of distribution are
probably `inexplicable' because an unrealistic concept of
dispersal is being used: for the same reason, the absence of
woodpeckers and trogons from New Guinea is `almost
mysterious', and the Vogelkop disjunctions in Astrapia,
Parotia, Paradisaea and others are `curious' or even `peculiar
in the extreme' (Frith & Beehler, 1998).
The central ranges divide Paradisaea minor Shaw and
P. raggiana Sclater into their northern and southern sectors,
as in other taxa such as Goura victoria Fraser and
G. scheepmakeri Finsch, Psittaculirostris edwardsii Oustalet
and P. desmarestii (Desmarest), and Lalage atrovirens Gray
and L. leucomela Vieillot (Rand & Gilliard, 1967). In a
centre of origin/invasion model the central ranges constitute
a barrier which has been crossed from either the north or
south. In the simpler vicariance model the northern and
southern ranges have evolved through allopatric evolution
following uplift, although this pattern may also have been
in¯uenced by terrane accretion. Similarly, in the Papuan
Peninsula Parotia splits up the Owen Stanley Range
between northern and southern watershed forms (Parotia
l. lawesii Ramsay and P. l. helenae De Vis) as does
Peneothello bimaculatus (Salvadori) with the nominate
subspecies in Irian Jaya and on the southern slopes of
SE New Guinea mountains, and P. b. vicarius De Vis on
Huon Peninsula and on the northern slopes of SE New
Guinea mountains. Detailed mapping is needed to decide
if this pattern is an effect of aspect, which in¯uences the
local climate even at such low latitudes, of terrane tectonics,
or both.
The craton margin in the Papua New Guinea
Highlands
Birds of paradise and bowerbirds both have their greatest
diversity of species per 1° ´1° square in the Mount Hagen ±
Wahgi Valley ± Jimi Valley square (Heads, in press). The
former margin of the Australian craton runs through this
grid square which is also geologically distinctive in having
several diverse accreted terranes, one an ophiolite complex,
juxtaposed there (Figs 4 & 29). As well as being a zone of
high diversity, the region along the craton margin represents
a major biogeographical break. Many mid-montane birds in
PNG are differentiated into western and eastern forms, and
often the break coincides with the craton margin (Figs 2, 4 &
29). Examples of this are given here.
The blue bird of paradise Paradisaea rudolphi (Finsch)
(Fig. 30) shows a clear subspecies break between Karimui
(on the craton) and Okapa (off the craton) well-documented
by Diamond (1972). A similar break is seen in other birds:
Coracina caeruleogrisea strenua Schlegel is in western New
Guinea, east to Karimui, C. c. adamsoni Mayr & Rand
replaces it at and east of Awande-Okasa (by Okapa);
Sericornis nouhuysi stresemanni Mayr ranges east to Wahgi
Valley and Mount Karimui; S. n. oorti Rothschild & Hartert
takes over from Okapa east to SE New Guinea.
The yellow-breasted bird of paradise Loboparadisaea
sericea Rothschild (Fig. 31) is also divided by the craton
margin into two subspecies, with a morphologically intermediate
population located right on the margin.
A similar distribution break is seen between Amalocichla
incerta olivascentior Hartert at Karimui and points west,
and A. i. brevicauda De Vis at Schrader Range, Huon
Peninsula, and SE New Guinea (Diamond, 1972). Three
Figure 29 Geology of the PNG Highlands
(greatly simpli®ed after Bain et al., 1972 and
Pigram & Davies, 1987) showing accreted
terranes (stippled), the ultrama®c Marum
terrane (hatched), craton margin (solid line),
intrusive rocks (black), Quaternary volcanic
rocks (v-symbols), and the Permian rocks of
the Kubor Mountains (cross hatched).
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908 M. Heads
Figure 30 The distribution of Paradisaea rudolphi in central
PNG (there are additional records of P. r. rudolphi further SE).
Figure 32 Orchidaceae. Corybas royenii Kores (triangles), Dendrobium
kerewense van Royen (stars), D. guttatum J.J. Smith (squares),
D. semeion van Royen (squares) (the af®nities of this species with
West Irian species are indicated by arrow), D. chamaephytum
Schlechter (continuous line), D. euryanthemum Schlechter (continuous
line), D. kerigomnense van Royen (at K ˆ Mount Kerigomna),
D. auranti¯avum van Royen (dots connected by dotted
line), D. alpinum van Royen (hatched line) and D. teligerum van
Royen (broken line).
Figure 31 The distribution of Loboparadisaea in the PNG Highlands
(L. s. sericea extends further west).
other species have races on the outlying Schrader Range,
north of the craton margin and between the Jimi and Ramu
Rivers, that are distinct from birds in the remainder of the
highlands: Melidectes rufocrissalis Reichenow, M. belfordi
De Vis, and Astrapia stephaniae.
It is interesting that parts of the Schrader terrane strongly
resemble the northern part of the Owen Stanley terrane
geologically (Pigram & Davies, 1987). If the Schrader
terrane should prove to be a dismembered portion of the
Owen Stanley terrane it would imply a left-lateral offset of c.
300 km along the Ramu-Markham and Bundi Fault Zones.
Similar biogeographical breaks at the craton margin occur
in other plant and animal taxa. The shrub Drimys piperita
entity `reducta' (Diels) Vink: Wissel Lakes, Mount Wilhelmina,
Mount Giluwe and the Kubor Mountains, and entity
`subalpina' Vink: Mount Wilhelm, act as a pair of `replacing
taxa' (Vink, 1970). Vink reported the `unexplained circumstance'
that the form of reducta most distinct from subalpina
is found at the Kubor Mountains ± the locality closest to
Mount Wilhelm, while the form which connects the two
morphologically, entity `subpittosporoides' Vink, is restricted
to Mount Wilhelmina. Again, this arrangement could be
explained by (right) lateral movement of terranes.
Other examples of plant differentiation around the craton
boundary include species of orchids (Corybas Salisb.,
Dendrobium Sw., Fig. 32; Glossorhyncha Ridl., Fig. 33),
Rhododendron L. (Fig. 34), Compositae (Tetramolopium
Nees, Fig. 35; Olearia Moench, Fig. 36) and Rubiaceae
(Amaracarpus Blume, Fig. 37) (distributions from van Royen,
1979±1983). Sometimes these angiosperms are assumed to
be recent groups, but recent molecular work has found that
Orchidaceae, for example, may have evolved `much earlier
than is traditionally believed' (Cameron, 2000).
Vertebrates other than birds also show the biogeographical
break at the craton margin clearly. The lizard Emoia p. purari
Brown ranges in PNG east to Karimui, while the second
member of the species, Emoia p. physicae (DumeÂril &
Bibron), replaces it from Wau eastwards (Brown, 1991).
Colubrid snakes (Fig. 38) show a similar distributional break.
In mammals, similar distributions are shown in marsupial
genera (Fig. 39) (Flannery, 1995) and bat species (Figs 40 &
41) (Bonaccorso, 1998).
Flannery (1995) observed that SE New Guinea (south of a
line: Kerema ± Garaina) is biogeographically distinct from
the central PNG highlands and has a `particularly high
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Biogeography of birds of paradise 909
Figure 33 Glossorhyncha ambuensis van Royen (Orchidaceae)
(square), G. nigrimarginata van Royen (dots connected with dotted
line), G. minjensis van Royen (triangle), G. ¯uviatilis van Royen and
G. pinifolia van Royen (at W ˆ Mount Wilhelm), G. altigena van
Royen (solid line), G. tenuis (Rolfe) van Royen (hatched line), G.
nigricans van Royen (stippled line), G. chlorantha van Royen and G.
tubisepala van Royen (at M ˆ Mount Michael), G. hamadryas
Schlechter (broken line); related to G. daymanensis van Royen of the
Maneau Range (arrow). Piora Koster (Compositae) at Mounts Piora
and Amungwiwa (triangles).
Figure 35 Tetramolopium procumbens Koster (Compositae)
(triangle with cross-hatching), T. macrum (F. Muell.) Mattfeld var.
glabrescens Koster (triangle with hatching, also at Mount
Carstensz), T. macrum var. album Koster (hatched line) (the third
variety in the species, var. macrum, is widespread through New
Guinea), T. alinae (F. Muell.) Mattfeld (continuous line), T. pioraense
van Royen (triangle) (showing af®nities with a species from
Mount Wilhelmina), T. ciliatum Mattfeld (broken line).
Figure 34 Rhododendron blackii Sleumer (Ericaceae) (horizontal
hatching), R. saxifragoides J.J. Smith (vertical hatching, also in Star
Mountains, Mount Wilhelmina, Mount Carstensz), R. vitis-idaea
Sleumer (continuous line), R. alticolum Sleumer (hatched line),
R. rubellum Sleumer (stippled line).
degree of endemism in mammals¼ Why these species have
not spread beyond the region is mysterious, as many of its
endemics are found over a wide altitudinal range¼ Competition
with near relatives could not be a factor, as the
nearest relatives of many of these endemics also exist in the
south-east. Furthermore there do not appear to be any
climatic or topographic barriers to dispersion¼'.
Summarizing, the effect of the craton boundary is the
same in orchids, rhododendrons, marsupials, snakes and the
Figure 36 Olearia lanata Koster (Compositae) (squares and stippled
line), O. hooglandii Koster at S ˆ Sugarloaf, O. lepidota
Mattfeld var. lepidota (hatched line, also at Star Mountains),
O. lepidota var. opaca Koster (triangles), O. monticola Bailey (three
subpecies) (solid line).
blue bird of paradise: southern and western forms are
separated from northern and eastern forms for no apparent
ecological reason but with the break precisely correlated
with the craton margin. The same distribution is shown by
organisms with very different ecology and means of dispersal,
indicating that these have not been primary factors
moulding the biogeography.
Under the heading `Anomalies', Frith & Beehler (1998)
noted that several birds of paradise that are otherwise
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910 M. Heads
Figure 37 Amaracarpus nummatus van Royen (Rubiaceae)
(triangles), A. montiswilhelmi van Royen (hatched line), A. clemensae
Merrill & Perry (continuous line).
Figure 40 The distribution of Miniopterus p. propitristis Peterson
and M. p. grandis Peterson (Chiroptera).
Figure 38 The distribution of Tropidonophis parkeri Malnate and
T. aenigmaticus Malnate (Serpentes).
Figure 41 The distribution of Rhinolophus arcuatus Peters and
Pipistrellus collinus Thomas (Chiroptera).
Figure 39 The distribution of Neophascogale Stein and Phascolosorex
Matschie (Marsupialia). Craton margin as stippled line.
widespread on the cordillera are absent from the Papuan
Peninsula. They used the term `Watut-Tauri Gap' to describe
the biogeographical boundary between the birds of the
Papuan Peninsula and those of the central Highlands of
PNG, and this is the boundary correlated above with the
craton margin. The exact location of this boundary remains
uncertain: Frith & Beehler (1998) wrote that `The southeastern
terminus of the distribution of Paradigalla, Pteridophora
and Epimachus fastuosus is the Kratke Range. It is
apparent there is some sort of distributional barrier southeast
of the Kratke Mountains'. Likewise, they write that
E. meyeri bloodi ranges east `presumably' to the Kratke
Range. However, Frith & Beehler are only predicting the
occurrence of these birds at the Kratke Mountains; their
actual known limits are Goroka, Okapa, Okapa/Kainantu
and Goroka, respectively, all lying even closer to the craton
margin.
The Kratke Mountains are nevertheless located at, or
near, an important biogeographical boundary in the group,
for example they mark the western limit of Paradisaea r.
rudolphi (Fig. 30; cf. Piora Koster ± Fig. 33). Other birds
such as Melidectes princeps range east to the Kratke
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Biogeography of birds of paradise 911
Mountains (Beehler et al., 1986), and are `strangely enough'
(Rand & Gilliard, 1967) not represented in SE New Guinea.
The Kratke Mountains are also an important centre for local
endemics, such as the fern Grammitis silvicola Parris (Parris,
1983). Although they are relatively accessible they are still
largely unexplored for birds of paradise. There are no
records of birds of paradise from a potentially very interesting
area between Mount Piora (Kratke Mountains) and
Kerema. This region of 150 ´ 50 km is covered in rainforest,
straddles the craton margin and includes the accreted
ultrama®c Menyamya terrane (Pigram & Davies, 1987;
not shown on the map of Bain et al., 1972).
Parts of the Bismarck Range (Jimi and Benabena terranes)
just north of the craton margin bear outlying populations of
many taxa otherwise found only on the craton, for example
Paradisaea rudolphi margaritae (Fig. 30). This could be the
result of local range expansion across the terrane suture, or
there may be a purely tectonic explanation: Pigram & Davies
(1987) indicated that the Jimi and Bena Bena terranes
(`stitched' together by the batholith which forms Mount
Wilhelm) are probably displaced portions of the northern
edge of the craton. The amount of displacement, if any, has
not been determined. The Mount Wilhelm batholith, whether
or not regarded as a separate terrane (Pigram & Davies,
1987 map it as part of the Australian craton) is separated
from the craton by the Bismarck Fault Zone and is
biogeographically distinct.
The north coastal ranges
The Idenburg, Sepik, Ramu and Markham Rivers form a
1300-km-long trough of structural origin separating the
central New Guinea cordillera from the north coastal ranges.
Gilliard (1969) wrote that `next to the central cordillera this
depression is the most important zoogeographical barrier on
the mainland of New Guinea'. The differences between the
faunas of the central ranges and those of the north coastal
ranges (e.g. Parotia lawesii compared with P. wahnesi) `are
of the sort one would expect to ®nd on moderately isolated
oceanic islands (which is perhaps what they once were), not
on mountains situated 12 miles apart across a narrow
valley!¼ Thus it seems that the Central Depression has,
and is still playing an important part in the speciation of
many lines of New Guinea animals'. While it is true that the
depression marks an important biogeographical boundary,
this may not have been caused by the depression as such but
rather by the long-term tectonic history of the terranes in the
region. It has been suggested that colonization across the
Mamberamo-Sepik-Ramu-Markham gulch by midmontane
birds has been `practically a one-way affair', from the central
mountains to the small northern mountain islands
(Diamond, 1972, 1985), but there is no real evidence for
these invasions over current geography. The Vogelkop ±
Huon disjunctions discussed above indicate that the
situation is much more complex, and probably involves
major tectonic changes.
Drepanornis bruijnii has `the most anomalous' and
`unexplained' range in the Paradisaeidae (Frith & Beehler,
1998): lowlands of NW New Guinea north of the central
depression from Geelvink Bay to Vanimo. However, a very
similar distribution is seen in many birds, such as the ®g
parrot Psittaculirostris salvadorii (Oustalet) (east Geelvink
Bay to Cyclops Mountains by Jayapura) (Forshaw &
Cooper, 1978; Beehler et al., 1986). One hypothesis Frith &
Beehler (1998) cited for the distribution is that D. bruijnii
differentiated in isolation in the north coastal ranges during
a period of high sea-level that ¯ooded the basins of the
Idenburg and Sepik Rivers. However, if the concept of
accreted terranes is correct the regions north and south of
the depression have been separated by much more than a
simple ¯ooding of the current topography.
The upper Watut Valley
Epimachus m. meyeri ranges through the Papuan Peninsula
north-west to Mount Missim, above the towns of Wau and
Bulolo. Similarly, Manucodia keraudrenii purpureoviolacea
Meyer ranges north-west to Wau, as does Lophorina superba
minor where it meets L. s. connectens Mayr possibly endemic
to the Herzog Mountains (although not recognized by Frith
& Beehler, 1998). From the other direction, Loboparadisaea
ranges through New Guinea, south-east to the nearby Herzog
Mountains and Wau. As well as being a boundary, Mount
Missim and the Herzog Mountains ( ˆ Mount Shungol)
comprise a centre of endemism for bird subspecies in Mirafra,
Pachycephala, Colluricincla, Melidectes, and Rhamphocharis
(Rand & Gilliard, 1967). Plants in this upper Watut River
region include Langsdorf®a Mart., known only from Mount
Missim, Madagascar, and tropical America (Hansen, 1974;
Streimann, 1983), and Hartleya, known only from Mount
Shungol and Mount Kaindi with sterile specimens from the
Vogelkop and its nearest relative, Gastrolepis Tiegh., in New
Caledonia (Sleumer, 1971). There are as many as six
Solanum species locally endemic in the upper Watut (Symon,
1985). Like E. m. meyeri, many plants endemic to SE New
Guinea reach their north-west limit here, for example
distinctive genera in Sapotaceae (Magodendron Vink ± Vink,
1995), Rubiaceae (Anthorrhiza Huxley & Jebb ± Huxley &
Jebb, 1991) and Monimiaceae (Kairoa Philipson ± Philipson,
1980). The area is the northern limit of the Owen Stanley
terrane schists, and is marked by mid-Tertiary intrusions,
mainly granodiorite, which form the mountains bounding
the Watut catchment: Shungol, Missim, Kaindi, and
Amungwiwa. Each of these is a centre of endemism for
different groups.
Diamond (1972) interpreted the distribution of Lonchura
species here as the result of recent, unpredictable colonization
± `An extreme example of this irregularity occurs in
the Herzog Mountains, where four different colonists
occur at four different localities within 35 miles:
L. tristissima in the Snake River valley, L. castaneothorax
at Mumena [ˆ Mumeng] Creek, L. grandis at Biolowat
[ˆ Bulowat], and L. spectabilis at Wau'. However, this
local vicariance may be related to distribution of each
species as a whole, and also to the complex tectonic
history of the area.
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912 M. Heads
Milne Bay islands
The islands of the D'Entrecasteaux and Louisiade Archipelagos
form an eastward extension of the New Guinea orogen
possibly related to the Owen Stanley terrane (Pigram &
Davies, 1987) and the D'Entrecasteaux islands include active
metamorphic core complexes (Tregoning et al., 1998). The
low Trobriand Islands to the north also lie within the belt.
Birds of paradise are represented in this region only by three
species of Manucodia. M. keraudrenii hunsteini is endemic
to the three D'Entrecasteaux islands. M. comrii Sclater is
known only from these same islands (M. c. comrii) and, at
the family's limit, the Trobriand Islands (M. c. trobriandi
Mayr); there is a spreading centre in the Woodlark Basin
(de Boer & Duffels, 1996a; Tregoning et al., 1998) and these
ranges may have been split apart by the opening of the basin.
Finally, M. atra Lesson has an endemic race, M. a. altera
Rothschild and Hartert, on Sudest ( ˆ Tagula) I. in the
Louisiades, but is not present on the D'Entrecasteaux or
Trobriand Islands.
It is striking that the only islands off New Guinea that
birds of paradise occur on ± northern Moluccas, Western
Papuan Islands, Japen, D'Entrecasteaux, Trobriands, and
Sudest ± all lie within the New Guinea orogen (Fig. 2). The
islands of Manam, Karkar and the Bismarck Archipelago lie
outside this belt and do not have birds of paradise. A very
similar distribution on the mainland and the Milne Bay
Islands, but absent from the Bismarck Archipelago, is seen in
the snake Tropidonophis aenigmaticus Malnate (Fig. 38).
Restricted island endemics, such as Semioptera and
Lycocorax on the Moluccas and Manucodia atra altera on
Sudest, are usually assumed to have been derived from a
widespread population on the mainland. However, the
island endemics may once have had a much more extensive
distribution on now-sunken land, for example around
Sudest, which is `obviously submerged' (LoÈ f¯er, 1977). In
this case birds that are currently `mainland' and `island'
forms are probably descendants of a common ancestor
formerly widespread over very different Mesozoic and
Tertiary geography. Likewise, areas of ocean ¯oor in the
Gulf of Papua, such as the Eastern Fields Fan (50,000 km 2 )
between Port Moresby and the northern end of the Great
Barrier Reef, have been subsiding ever since the Coral Sea
began rifting open in the Miocene (Mutter, 1975). This
could explain biogeographical connections between the
trans-Fly and Port Moresby regions `cutting the corner'
across the Gulf of Papua, seen for example in several snakes
mapped by O'Shea (1996).
The island taxa cited above include distinctive endemic
genera, as well as barely differentiated taxa, but the same
principle may apply. Minor morphological and molecular
differences may re¯ect ancient but rapid and minor evolutionary
divergence followed by a long periods of stasis, with
possible geographical convergence of populations on converging
terranes.
Rand & Gilliard (1967) cited many species, for example in
Eos (Fig. 15), which `favour' small islands. But perhaps these
taxa have no choice if small islets form the only land currently
available in their respective regions. The islets may represent
the last land in an area of subsidence, and competition from
related forms prevents establishment in neighbouring territory.
These birds survive on small islets and atolls because,
®rstly, they were already in the region in a prior geography,
and secondly, because they either possessed the necessary preadaptations
for this ecology or were able to adapt. The vast
majority of small islet taxa around New Guinea are not found
on all the many islets available, but only those in particular
regions. This implies that something other than the small islet
ecology is determining the distribution.
Northern limits of birds of paradise and bowerbirds
Despite being on the western Papuan Islands and the Milne
Bay islands, no birds of paradise or bowerbirds are known
from the offshore islands of Biak, Karkar, Manam, New
Britain, or New Ireland, all of which provide suitable habitat:
hills with closed rainforest. The island of Karkar, for example
(Fig. 4), is 25 km across and 1850 m high, largely covered in
rainforest and only 15 km offshore. Yet there has never been
a single record of a bird of paradise or bowerbird there. New
Britain is a much larger island, 90 km off New Guinea. A
surprising 70% of the species on the part of New Guinea
opposite New Britain are not represented on New Britain
(Mayr, 1940). Gressitt (1982b) frankly admitted that the
absence of many New Guinea groups from the Bismarck
Archipelago, `in spite of proximity and island steppingstones',
is `puzzling'. In fact the avifauna of these islands is
both rich (Coates, 1990) and quite different from that on the
mainland ± many ¯oristic and faunistic works (e.g. Rand &
Gilliard, 1967; Beehler et al., 1986) are logically limited to
the mainland taxa. Because the offshore islands are so close it
seems that `dispersal' in the sense of physical movement, or in
this case lack of dispersal, has nothing to do with the major
faunistic difference. On the other hand, it is surely not a
coincidence that the northern boundary of the New Guinea
orogen runs along the north coast and marks the mutual
boundary of the two faunas, including the northern limit of
Paradisaeidae and Ptilonorhynchidae.
The distinctive fauna of Karkar and the other fringing
islands includes birds such as Charmosyna rubrigularis
(Sclater), Macropygia mackinlayi (Ramsay), Cacomantis
variolasus fortior (Rothschild & Hartert), Ducula pistrinaria
Bonaparte, Monarcha cinerascens Temminck and Myzomela
sclateri Forbes (maps in Coates, 1990). These are all on
Karkar and several of the other northern islands (New
Britain, etc.) but are not on the New Guinea mainland,
where they are replaced by allied forms. At subspecies level
Gallicolumba b. beccarii (Salvadori) is in the mountains
throughout New Guinea, and G. b. johannae (Sclater) is on
Karkar Island and the Bismarck Archipelago. Megapodius
freycinet (Gaimard) shows the boundary well, with
M. f. af®nis Meyer in northern New Guinea and M. f.
eremita Hartlaub on Manus, Long Island, Siassi (ˆ Umboi
or Rooke) Island, New Britain, and the Solomon Islands.
Karkar Island, on the biogeographical boundary between the
two, has a `mixed population' (Rand & Gilliard, 1967).
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Biogeography of birds of paradise 913
The Geelvink Bay islands also have a distinctive fauna.
Here there are birds of paradise on Japen Island but not the
neighbouring Biak Island to the north. Conversely, the owl
Otus Pennant is widespread in America, Africa, and Eurasia,
but is represented in the New Guinea region only by
O. beccarii Salvadori of Biak Island, the rubiaceous plant
Badusa A. Gray, widespread from the Philippines through
the Paci®c, is also in New Guinea only on Biak (Smith,
1979±1996), and the land snail Palline ranges through the
Caroline Islands (Palau and Ponape) and is elsewhere only
known on Biak (Solem, 1983). The Biak Island fauna is
related to that of the PNG islands to the east through the
absence of groups like Paradisaeidae, and also in the
presence of taxa such as Monarcha brehmii, endemic to
Biak Island and with its nearest relatives in the Bismarck
Archipelago (Rand & Gilliard, 1967).
These offshore islands should not be seen as having a
depauperate avifauna. In Accipiter, New Britain has ®ve
species, three endemic. This is the richest Accipiter fauna
of any part of the world (Wattel, 1973): New Guinea,
twenty-four times the size of New Britain, has six or seven
species, three endemic, and Australia, 200 times the size,
has three species and no endemics. Can this massing of
Accipiter on New Britain and the total absence of
Paradisaeidae and Ptilonorhynchidae there really be explained
as the result of different powers of ¯ight in these
bird groups? This would account neither for the `striking
resemblance' Wattel (1973) noted between the New Britain
endemic A. brachyurus and A. erythrauchen of the
Moluccas, nor the `chain of¼ relict species' on the islands
which festoon northern New Guinea: A. henicogrammus
(northern Moluccas), A. luteoschistaceus (New Britain)
and A. imitator Hartert (Solomon Islands). It seems likely
that the New Britain massing and its far-¯ung connections
with Biak and the Moluccas have more to do with the
distribution of ancestral pre-Accipiter ± proto-Accipiter in
the region north of New Guinea and regional tectonics
than with chance, over-water dispersal.
Within Sibley & Ahlquist's Corvinae, the Paradisaeidae,
Cracticidae, Grallinidae, Oriolidae are absent as such from
the Bismarck Archipelago, but represented there by other
Corvinae: Corvidae (one species), Campephagidae (®ve
species) and Artamidae (one species). Again, the question
is: are the ®rst four families absent and the last three families
present because of differences in means of dispersal/ecology,
or because of different prior massings and evolutionary
history? In this connection Artamus insignis Sclater (Artamidae),
endemic to New Ireland and New Britain, is of special
interest. This bird has a completely white back and as its
name suggests is very distinct from the mainland species,
with a black back. Rutgers (1970) observed that A. insignis
is undoubtedly closely related to Artamus monachus of
Sulawesi and the Sula Islands, which differs only in that the
wings and tail are not quite so black. Rutgers concluded that
A. insignis could even be a local variety of A. monachus.
This major disjunction (Fig. 42) is probably a variant of the
Moluccas ± New Britain connection cited above in Accipiter,
Christensenia and Spathiphyllum. The Sula Platform is a
Figure 42 Track a: the related species Artamus monachus (two
subspecies; distributions approximate) and A. insignis. Track b:
af®nities between disjunct species pairs in Paradisaea, Astrapia and
Parotia. Track c: the main massing of Paradisaeidae.
fragment of continental crust adjacent to the east arm of
Sulawesi which may have originated in central New Guinea
and undergone a lateral displacement of more than 2500 km
to its present position (Pigram et al., 1985). This could
explain the Artamus pattern.
The Sulawesi ± Bismarcks disjunction in Artamus is similar
to disjunctions north of New Guinea in other taxa, including
that of the plants Byttneria Loe¯ing, with no records between
the Philippines ± Sulawesi and New Britain (sterile collection)
(AveÂ, 1984), Ochthocharis javanica Bl. in Peninsular
Malaysia Peninsula and Borneo, disjunct at Manus Island
(Hansen & Wickens, 1982), Deplanchea glabra Steen. in
central east Borneo and Central Sulawesi, disjunct at the
Jayapura region (van Steenis, 1977), and Tabernaemontana
remota, known only from Sulawesi and the Louisiades
(Rossel Island) (Leeuwenberg, 1991). The last three species
have vicariant congeners on mainland New Guinea.
Philippines ± Manus/New Ireland connections are welldocumented,
for example in the ferns Culcita straminea
(Labill.) Maxon (Holttum, 1963), Coryphopteris squamipes
(Copel.) Holttum (Holttum, 1981), Ctenitis pallens (Brackenr.)
M.G.Price, Tectaria tabonensis M.G. Price/T. subcordata
Holttum (Holttum, 1981), and in insects the
Leucophoroptera philippinensis species group (Homoptera:
Miridae) (Schuh & Rosendahl, 1986).
ECOLOGY
Birds of paradise are mainly con®ned to rainforest in a broad
sense, including secondary forest and regrowth. However,
Manucodia atra commonly inhabits open savanna woodland
as well as lowland rainforest, and M. comrii ranges from
mangrove through savanna woodland, low altitude forest
and also stunted, mossy, high-altitude forest.
Species of birds of paradise occupy different elevation
zones from sea-level to 3500 m, with most (thirty of thirtyeight
species) occurring in the 1000±2000 m altitudinal
band. Although most species of Paradisaeidae are thus
`lower montane', it is interesting that members of at least
®ve, possibly six, genera frequent coastal communities such
as mangrove or at least the landward back-mangrove
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914 M. Heads
communities that are far more species-rich than is often
realized. Lycocorax is found in mangroves (as illustrated by
Cooper & Forshaw, 1977); Manucodia atra is recorded from
mangroves; M. comrii, M. keraudrenii and Ptiloris magnificus
(Vieillot) occasionally frequent mangroves, and P.
victoriae Gould is recorded from the landward edge of
mangrove (Gilliard, 1969; Frith & Beehler, 1998). Seleucidis
Lesson occurs in a range of lowland forest types, but shows a
particular af®nity for permanently or seasonally ¯ooded
swamp forest often with pandanus and sago palm, and has
also been observed in or near mangrove (Gilliard, 1969).
Paradisaea raggiana has also been recorded calling in
mangroves (Frith & Beehler, 1998). In addition, Drepanornis
bruijnii can be found within a kilometre or two of the coast
(Frith & Beehler, 1998) (possibly not actually on the coast),
for example in limestone hills where it is more abundant
than in a nearby site in lowland alluvial forest.
Like the birds of paradise, the bowerbirds also have their
greatest diversity in New Guinea, are mainly forest birds,
and are most diverse in the 1000±2000 m band (twelve of
thirteen species) (Cooper & Forshaw, 1977). However,
Ailuroedus crassirostris (Paykull) occurs in coastal
scrub, Chlamydera cerviniventris Gould is never far fom
the coast, often close to beaches, swamplands and mangrove
swamps, and C. nuchalis Jardine & Selby is rarely found far
from water, either freshwater or salt.
Altitudinal `anomalies' in New Guinea
Some of the most obvious ecological changes in mountainous
areas are those associated with changing altitude.
Diamond (1972) and Frith & Beehler (1998) suggested that
sorting by elevation is perhaps the most important ecological
mechanism permitting the adaptive radiation of birds of
paradise. The elevational distribution of the New Guinea
birds is usually assumed to have been attained, again, by
dispersal, usually from a lower altitude centre of origin into
new, originally sterile regions at higher altitudes. However,
altitudinal `anomalies' in New Guinea birds have been noted
by many ornithologists. Iredale (1950) described the altitudinal
replacement of the paradisaeid genera, but noted that
in addition a `locality factor' is present; related forms in
different parts of the island sometimes occur at different
altitudes (cf. Rand & Gilliard, 1967, p. 14).
Under the heading `Descent of mountain birds to the
lowlands' Rand & Brass (1940) wrote that `as with plants, a
number of birds which over most of New Guinea occur only
in the mountains, such as Cleytoceyx rex and Diphyllodes
(Cicinnurus) magni®cus, come to near sea level on the upper
Fly River. The prevalence of mist and cloud conditions,
lowering the light intensity, may have an effect in producing
the conditions recalling cloud-shrouded mountain forest.
However, this will not apply to Myzomela nigrita and
Ailuroedus melanotis (sometimes included in A. crassirostris)
which reach the Wassi Kussa River (lower Fly), where
relatively dry, bright conditions prevail much of the year'.
(Ailuroedus crassirostris in south New Guinea is known only
from sea-level, but `trapped' in the Snow Mountains it
occurs from 810 to 1140 m). Likewise, the bowerbird
Sericulus aureus is in the lowlands and foothills of the Fly
Platform in the southern watershed, but in northern New
Guinea is con®ned to hill forest at 1000±1400 m (Pratt,
1982; Beehler et al., 1986). Diamond (1972) listed the
`enigmatic' distributions of twenty-®ve primarily montane
species at or near sea-level at the Fly River mouth, and Pratt
(1982) regarded these as `by far the most peculiar geographical
problem of hill forest birds'.
Karimui basin (sometimes mapped as `Karimui Plateau')
by Mount Karimui is another classic site of altitudinal
`anomalies' (Diamond, 1972). It is a ¯at basin about
14 km wide at 1050 m altitude, largely sealed off from the
outside by a ring of mountains. The avifauna is distinctive
and, oddly, typical of the sea-level lowlands rather than
hill forest. It includes twenty-seven lowland species (including
Cicinnurus regius and Ailuroedus buccoides) whose
altitudinal ceiling elsewhere lies considerably below
1050 m, and some of these are only known elsewhere
from sea-level. The basin avifauna is also noteworthy
through the absence of some species usually found at this
altitude, and by three striking, locally endemic forms. In
seven cases an unexpected lowland species that is present
and an unexpectedly absent highland species are successive
members of an altitudinal sequence, so that the `wrong'
member is present, for example A. buccoides is present
instead of A. crassirostris.
Diamond explained these phenomena as `ultimately due to
the ¯atness of the basin ¯oor' but Charmosyna placentis
Temminck seems to contradict this ± it is normally at sealevel,
but ranges beyond the basin to 1425 m on Mount
Karimui.
Altitudinal `anomalies' are common in other parts of New
Guinea and include the following passerines:
Gerygone magnirostris Gould is usually in the lowlands,
but at Baiyer River near Mount Hagen it occurs at 1050 m,
an altitudinal record for the species.
Rhipidura leucophrys (Latham) is a widespread lowland
species in New Guinea. It is also found in montane
grassland, but only from Eastern Highlands Province west
to Telefomin where it is ubiquitous. It is strangely absent in
the montane grasslands of the Huon Peninsula, SE New
Guinea and Irian Jaya.
Pachycephala pectoralis (Latham) is widespread in
southern New Guinea and the Milne Bay Islands in
mangrove swamps and other coastal vegetation, but it is
also present in Irian Jaya, trapped in the upper Balim
Valley below Mount Wilhelmina in dry mid-mountain
forest at 1350±2310 m.
Altitudinal anomalies are often associated with phylogenetic
differentiation. Populations of Pachycephalopsis
modesta (De Vis) at Mount Karimui, Mount Michael and
the Kubor Mountains occur at 1800±3300 m, but in SE New
Guinea other races descend to 1260 m (Owen Stanley
Mountains) and 1050 m (Herzog Mountains).
Myzomela erythrocephala Gould is restricted to mangrove
swamps of northern Australia and southern New Guinea,
but shows remarkable similarity in colour and pattern to the
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Biogeography of birds of paradise 915
smaller M. adolphinae Salvadori which ranges in the New
Guinea mountains from 810 to 1800 m (Rand & Gilliard,
1967).
Altitudinal anomalies in New Zealand taxa have been
explained as the direct effect of vertical tectonic movements
(Heads, 1989), and this may also be true in New Guinea.
Much of the north coast of New Guinea has been uplifted
and this has led to the formation of steep bluffs. Raised coral
reefs are known from Madang, Trobriand Islands, Woodlark
Island, the Bismarck Archipelago, and the northern
Huon Peninsula where they form stair-case-like terrace
sequences more than 600 m high and including more than
twenty terraces.
On the other hand, parts of southern PNG, such as Sudest
Island, have been sinking. On the mainland the south coast
has bluffs and cliffs only in a few areas, indicating general
subsidence or lack of uplift. Between Mullins Harbour and
Samarai there are characteristics of a drowned coastline and
this is also seen in the north at Cape Vogel (LoÈ f¯er, 1977).
Uplift in the north and sinking in the south may explain
why birds such as Sericornis virgatus Reichenow occur at
600±1250 m in the north and west New Guinea, while
S. beccarii (Salvadori) of the same superspecies is at 0±710 m
in southern New Guinea and northern Australia, and why
Melidectes foersteri Rothschild & Hartert of the Huon
Peninsula is at much higher altitudes (2460±3600 m) than its
sister species M. rufocrissalis Reichenow of the central
ranges (1500±2250 m) (Diamond, 1986).
Altitudinal `anomalies' and `locality factors' in New
Guinea are not restricted to birds and most other groups
show similar patterns. Ninety years ago in the upper Ramu
valley at Kenejia, Schlechter (1982) was surprised to ®nd
typical sea-shore plants such as the orchid Dendrobium
antennatum Lindl. Schlechter also noted uplifted coral at
600 m on the Huon Peninsula, and reasoned correctly that
the Ramu-Markham valley was previously ¯ooded by the
sea, but that an `enormous elevation' subsequently joined the
Huon Peninsula to the mainland. Similarly, van Steenis
(1984) recorded mangroves in Malesia which have been
stranded inland through tectonic uplift.
Brook®eld & Hart (1971) noted the raised beaches on the
Huon, while `conversely on the southern plain of New
Guinea it seems that some forest is being actively transformed
into swamp forest through depression along axes
transverse to the central cordillera'. Stevens (1982) described
`altitudinal irregularities' in the ¯ora of the upper Fly River
(Kiunga) like those in the avifauna there, with species of
otherwise montane genera present on ridges at only 100 m
elevation. In the Lakekamu basin SW of Wau, Takeuchi &
Kulang (1998) reported `unexpected' montane genera in
families such as Ericaceae, Monimiaceae, Elaeocarpaceae,
Winteraceae, Ternstroemiaceae and Pittosporaceae at
anomalously low altitude (175 m), very near the alluvialcoastal
plain. Individual species are found there far below
their previously known lower limit. Takeuchi (2000)
inferred `the apparent displacement of an entire montane
assemblage to the Papuan lowland environment where the
non-conforming elements now coexist in disparate combination
with the conventional lowland ¯ora'. As Takeuchi &
Kulang noted, these records are `rather provocative and
deserving of further enquiry'.
In other fauna, Gressitt (1982b) noted that helminths and
crustacea of terrestrial caves in New Guinea may have
evolved directly from marine forms with the uplift of the
island. The ®sh Clupeoides venulosus Weber & de Beaufort
inhabits the Lorentz and Fly rivers up to 500 m and is the
only herring (Clupeidae) to inhabit mountainous rivers
(Allen, 1991). Morelia boeleni Brongersma is probably the
only python in the world that lives as high as 3000 m
(Mount Albert Edward ± Mackay, 1976).
Discussing the site of most rapid current uplift in New
Guinea, the Huon Peninsula, Flannery (1995) found it
`remarkable' that mammals normally restricted to middle
altitudes, for example the marsupials Phalanger carmelitae
Thomas and Peroryctes rafrayana (Milne-Edwards), extend
there into the alpine zone.
Within the New Guinea avifauna as a whole, as with the
¯ora, there is an average decrease in size with increase in
altitude as alpine conditions select against large forms.
However, Rand & Gilliard (1967) observed that within
species such as Cacatua galerita Latham (Psittacidae) and
Collocalia esculenta Linnaeus (Apodidae) there is an
increase in size with altitude. They concluded that `There
is no obvious explanation for the existence of these apparently
contradictory patterns', but this contradiction and
associated cladistic incongruence are precisely what would
be expected if prior clines running in different directions
were both caught up in the same orogeny.
Geological uplift and biological `invasion'
of the mountains
Many biologists studying New Guinea communities have
assumed that geological uplift takes place over too long a
time scale to be relevant to biology. Nevertheless, geologists
have calculated the spectacular rates of 2.1 m per 1000 years
(Abbott et al., 1997) and 3 m per 1000 years (LoÈ f¯er, 1977)
(Beehler et al., 1986; quoted a rate of 3 cm per 1000 years,
but this is probably a misprint). Such a rate gives an
ecologically signi®cant shift of up to 300 m in 100,000 years,
and could turn a mangrove fauna into an upper montane
fauna at 3000 m in just 1 Myr. Relic surfaces, presumably
bearing ¯ora and fauna, have been lifted high into the
mountains. For example, the extensive Neon Basin currently
located at 2800 m in the Owen Stanley Range, and also a
basin near Mendi, have both formed near sea level (LoÈ f¯er,
1977). Relic surfaces rise from 200 m at the eastern tip of the
New Guinea mainland (where many otherwise `montane'
genera are present at low altitude) to over 3000 m on Mount
Albert Edward (where the generally lowland pythons occur
at high altitude), and show the effects of differential Pliocene-
Pleistocene uplift. Relic surfaces are also present around
Goroka, but these are much less regular because of a
multitude of different movements along major faults.
The well-known phenomenon in which taxa occur at
higher altitude on higher mountains than on small ones, even
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916 M. Heads
where the taxa do not range to the top of the latter, could be
partly explained by differential uplift ± the mountains are
lower in Milne Bay, for example, because there has been less
uplift there and for the same reason the altitudinal vegetation
bands have remained telescoped together. The more or
less constant wet-season mists also lie much lower on these
isolated mountains than in the central Highlands, where they
usually only descend to about 2700 m (pers. obser., around
Goroka). This may explain the survival of moss forest
communities at low altitudes on the isolated mountains, but
perhaps not their origin.
It is often thought that mountains are uplifted and then
invaded by a new ¯ora and fauna from elsewhere. However,
before the land was uplifted it was not an ecological vacuum.
There would have been a diverse array of plants and animals
present, some of which would have been able to survive uplift
by pre-adaptation (or adaptation), while many other populations
would die out. This would allow pre-adapted taxa to
attain a very wide altitudinal range, and many such taxa are
known in New Guinea. Like the family Paradisaeidae, the
most diverse bird genera in New Guinea, Ptilinopus Swainson
(fourteen species) and Pachycephala (®fteen species),
range from mangrove forest to 3400 and 3650 m, respectively,
and at species rank trees like Schuurmansia henningsii
range widely from sea-level to 3000 m (Kanis, 1978).
Whether the `montane' elements occur at low altitude
through downwarping of terranes bearing these populations,
or because there has been relatively little uplift there
compared with the main central mountains, it seems
unrealistic to discuss the altitudinal range of communities
and taxa without reference to the geological changes of
altitude by orogenic and epeirogenic uplift, sedimentation,
downwarping and erosion.
Ophiolite endemism
It is suggested here that the distributions of the birds of
paradise mainly re¯ect geological change, and are generally
much older than was thought. Unlike chance dispersal and
chance extinction this tectonic hypothesis seems to account
for some of the standard aspects of the distribution patterns
and leads to interesting, testable correlations.
An example of biogeographical and tectonic correlation is
that of endemism on ultrama®c terranes. Rocks with less than
45% silica are rare and are termed ultrabasic or ultrama®c
(that is, high in magnesium and iron). They usually occur as
part of ophiolitic igneous suites, or ophiolites, which comprise
pillow basalts, massive gabbros, and serpentinized
ultrama®cs. The presence of ultrama®cs on the earth's
surface is of great tectonic signi®cance as they are sections
of oceanic crust and upper mantle that have been uplifted and
obducted onto land (rather than subducted below it). This
has occurred at plate margins during island-arc collision, and
accreted arc terranes and orogenic belts frequently include
ophiolites. In the Western Papuan Islands, Waigeo, Batanta
and nearby Ko®au (but not Salawati) comprise an ophiolite
complex, the Waigeo terrane (Pigram & Davies, 1987).
Waigeo and Batanta are also distinguished by the presence of
local endemics such as Cicinnurus respublica (Bonaparte)
and Paradisaea rubra (Fig. 27). Similarly, Melidora Lesson
(Alcedinidae) is widespread in New Guinea west to Waigeo
and Batanta, but is not on Salawati. The straits between
Salawati and Batanta Islands are less than two miles wide,
but `have prevented the crossing' of seventeen species of
Salawati birds to Batanta and ®ve from Batanta to Salawati
(Mayr, 1940). It seems more likely that this striking faunistic
difference is due to different tectonic and evolutionary
histories, rather than to a 2-mile wide sea-barrier.
The New Guinea orogen is characterized by abundant
outcrops of ultrama®c rocks. The largest of these, the
Papuan Ultrama®c Belt (Bowutu terrane) covers an area
400 ´ 40 km and is one of the world's most spectacular
ophiolites. It forms a series of subsidiary mountain ranges
north of the main ranges of the Papuan Peninsula and its
emplacement must have been a major tectonic event.
Botanists have long recognized that these northern New
Guinea ultrama®cs were strong foci of endemism (e.g.
Kairothamnus Airy Shaw ± Airy Shaw, 1980; Calophyllum
streimannii Stevens ± Stevens, 1974a), but it was felt that
much of this endemism was the result of edaphic rather than
historical factors. Polhemus (1996) pointed out that although
many animals (e.g. Parotia lawesii helenae) show similar
patterns, zoologists have been slow to realize that this
correlation greatly weakens the edaphic hypothesis. Instead,
Polhemus (1996) regarded the ophiolites as biogeographically
signi®cant because they are arc terrane markers. The
most mature phase of arc collision is seen in old arc fragments
now deeply embedded in modern mainlands, such as New
Guinea and the Philippines. The remnants of these Mesozoic
arc systems have been crushed between even older arcs or
continents but have left a biological signature in the disjunct
distributions of living taxa.
Survival of taxa in situ
At ®rst it seemed unlikely that bird taxa would maintain
their distributions over geological time as precisely as
indicated here. However, results from another ®eld ±
ecological studies of current populations ± also show that
New Guinea rainforests and their bird fauna have a great
capacity to survive more or less in situ, despite high levels of
disturbance by volcanic activity, movement on faults,
landslides, rivers changing course, storms, human activity,
and as seen dramatically in 1997, drought and ®re. Life is
`stickier' and less easily `eroded' away than biologists often
assume. Comparatively few New Guinea rainforest trees
regenerate in full shade and the long-held idea of tropical
rainforest as fragile and undisturbed has more recently been
rejected by ecologists (Johns, 1986). So it is not surprising
that while all birds of paradise are generally found in closed
rainforest, the vast majority are also occasionally seen in at
least one of the following: forest edge, secondary or broken
forest, selectively logged forest, disturbed forest near villages,
abandoned gardens, and even open agricultural land with
scattered shrubs. Parotia se®lata is most abundant in wellestablished
secondary forest, Lophorina superba (Pennant) is
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Biogeography of birds of paradise 917
well-known around gardens and on houses, and Cicinnurus
magni®cus (Pennant) and Ptiloris victoriae have been recorded
breeding in secondary growth and gardens (Frith &
Beehler, 1998). Of the ®ve birds of paradise recorded only
from `forest', Paradigalla carunculata Lesson, Astrapia nigra
and A. rothschildi are very poorly known in the ®eld, and
Manucodia jobiensis Salvadori and Paradisaea apoda are
also rather poorly known. The latter at least probably occurs
in disturbed vegetation as do all the other Paradisaea species;
P. raggiana is considerably more numerous in ecologically
disturbed areas than in the forest interior (Diamond, 1972)
and in some sites P. rudolphi is easily observed in gardens
and at forest edge (Beehler et al., 1986) although it will not
tolerate intensive gardening (cf. Diamond, 1972).
Mangroves form a succession on shifting intertidal mud
banks. It was mentioned above that at least ®ve out of
fourteen genera of Paradisaeinae (35%) are found in
mangrove and associated vegetation. Similarly, in the
Sapindaceae, an important family of rainforest trees, nine
of the forty-two Malesian genera (21%) occur in or around
mangrove and eleven others (26%) are known from coastal
cliffs and sands (data from Adema et al., 1994). In New
Guinea Euphorbiaceae eleven out of fourty-seven genera
(25%) are recorded in or around mangroves (Airy Shaw,
1980). In these and other birds and trees the New Guinea
mangrove shows clear af®nities with dry-land rainforest, and
there is also an obvious link between mangrove and the more
or less freshwater swamp forests found along the central
depression in New Guinea.
In many birds there are direct ecophyletic links among
taxa of mangrove, back-mangrove and secondary, disturbed
vegetation. For example, Geopelia humeralis (Temminck) is
particularly associated with mangrove swamps and disturbed
places in and around human habitation (Rand &
Gilliard, 1967).
Finally, more broken, lower mangrove often provides an
impenetrable tangle of woody vegetation similar to that of
subalpine forest, and Manucodia comrii frequents both.
Because of these factors, populations of what are currently
mountain birds may not necessarily need mountains to
survive; as Mayr (1953) noted, birds often show remarkable
independence from habitat restrictions.
The unmistakeable ribbon-tailed Astrapia mayeri Stonor,
with the longest tail for its body of any bird, is possibly
another example of survival more or less in place, despite
massive local disturbance. It is only found in the Karius
Range (SW of Tari), the nearby Doma Peaks, mountains by
Laiagam, Mount Giluwe and Mount Hagen, and so is
largely restricted to Quaternary volcanoes. Similarly, the
striking bowerbird Archboldia papuensis sanfordi Mayr &
Gilliard is only known from Mounts Giluwe and Hagen
which are also major centres of endemism for plants. Can
prior, Tertiary endemics survive such extensive volcanic
activity? It would usually be inferred that a vast area has
been biologically sterilized and must have been repopulated
by long distance dispersal.
Naturally life cannot survive literally in situ on molten
lava, but individual lava ¯ows are often rather narrow.
Many very recent ones on the volcanic islands north of New
Guinea resemble straight, sealed roads running through the
rainforest, and make for easy walking. The forest is
obviously eliminated along the path of the ¯ow, but
regenerates quickly. Lava ¯ows do not cover an entire island
such as Manam or Karkar all at once, but over thousands or
millions of years, eruption by eruption. This allows the biota
to survive, more or less in situ, by constantly colonizing
younger ¯ows from older ones until the entire island may
eventually be covered by younger strata and the older living
communities which have `¯oated' on them (cf. Craw et al.,
1999, Figs 2±5). Many plants of active margins are surprisingly
tolerant of volcanic activity, and the ash is often highly
fertile. After eruptions on the volcanic islands north of New
Guinea mainland, palm nuts germinate in the steaming ash
following the ®rst rain, and plants such as Thymelaeaceae,
Symplocaceae, Ericaceae and Epacridaceae often thrive in
active craters around the Asia-Paci®c region (Pers. obser.).
Means of dispersal or means of survival?
Many ornithologists have questioned the apparent signi®cance
of birds' means of dispersal in establishing their
distributions, as the following quotations indicate:
Birds offer us one of the best means of determining the
law of distribution; for though at ®rst sight it would
appear that the watery boundaries which keep out the
land quadrupeds could be easily passed over by birds, yet
practically it is not so¼ (Wallace, 1962 [1869]).
To the person who is impressed by the bird's potential
mobility, the occurrence of the same or representative
species at widely separated localities is simply a matter
of ¯ight from one station to the other¼ But the avian
geographer is not so easily answered. He knows that
most birds are closely con®ned to their own ranges¼
(Chapman, 1926).
Most species of birds, especially on tropical islands, are
extraordinarily sedentary (Mayr, 1940).
That birds can ¯y across barriers is one of those
apparently simple facts that are not simple. (Darlington,
1957).
One of the ®rst facts that strikes the student of bird
distribution is that most birds, in spite of the very great
mobility resulting from the power of ¯ight, have sharply
demarked distribution (Van Tyne & Berger, 1959).
Despite powers of dispersal through the air, we have the
paradox that ornithologists constantly stress the value of
birds as objects of distributional and dispersal studies
derived from the fact that known cases of such dispersal
are so rare (Deignan, 1963).
It has been shown many times that the apparent `means of
dispersal' proposed as an explanation of distribution do not
correlate with actual distributions. For example, studying
the eighty-three species of swifts (Apodidae) Brooke (1970)
observed that these are among the strongest-¯ying land-birds
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918 M. Heads
and are usually gregarious. He concluded: `One might
suppose that such birds would be exempt from the standard
zoogeographical patterns, but this is not borne out by an
examination of their breeding distribution. In fact, standard
zoogeographical patterns emerge¼' One such pattern is the
curious poverty of forms on Madagascar and Australasia,
also seen in woodpeckers and many other groups.
Frith & Beehler (1998) suggested that `both Manucodia
and Paradisaea have dispersed across deep-water barriers¼
over water differentiation follows chance dispersal across a
permanent water barrier. Although this is evidently a rare
event in the birds of paradise, it has produced six insular
species¼ Apparently over-water dispersal is a highly effective
pathway to speciation in birds of paradise'.
However, this begs the question: why has over-water
dispersal not been effective in getting the birds to the nearby
islands fringing northern PNG?
A related problem with long-distance dispersal is not
concerned with how it could occur in the ®rst place ± that
seems obvious in birds, mammals, ferns, orchids, etc., all
with their ordinary means of survival ± but how and why the
`invasion' would be occurring at one period in time and then,
for no apparent reason, cease, and such a cessation is
necessary for allopatric evolution. To explain this without
invoking geological change biologists have often employed a
concept of `chance dispersal' which can `explain' any pattern
at all, but is ad hoc and untestable.
In 1605 Clusius already knew that Paradisaea apoda lives
on the Aru Islands, while P. minor is on the western Papuan
Islands (Gilliard, 1969). Since that time vicariance (that is,
geographical replacement or representation) has been discovered
in many birds and since the 1890s the use of
trinomials in ornithology and mammalogy has been based
on the ubiquitous phenomenon. The impression on reading
through a list of world birds and their ranges is not one of
active range expansion, but one of each bird's localized
distribution interlocking in a vicariant way with that of its
relatives, forming just one tile in a global mosaic. Perhaps
the normally observed powers of physical movement in birds
that are crucial for survival (feeding, avoiding predation,
reproduction, etc.) are of little signi®cance in establishing the
geographical range of taxa.
During periods of major tectonic and physiographical
change, such as rifting and terrane accretion, whole faunas
may well expand their range, for example along new shore
lines, but in birds such as the Paradisaeidae there is no
evidence for recent, long-distance dispersal over modern
geography. In fact most birds of paradise appear to be
sedentary forest dwellers with relatively small home ranges
(Frith & Beehler, 1998) and rather than their biogeography
being determined by their ecology, the ecology of the birds
(for example, their altitude) may be determined by their
prior biogeography and subsequent tectonic developments.
The age of birds
Evidence is mounting that most groups of birds are considerably
older than was thought. Ever since Matthew's (1915)
very in¯uential text on vertebrate palaeontology, a literal
reading of the fossil record is the technique which has featured
in most work on the chronology of evolution. This would
suggest, for example, a Tertiary radiation of the mammal and
bird orders. The fact that no bird of paradise fossils are
known would be taken as evidence for a very young age of the
group. However, new palaeontological and molecular evidence
(e.g. Hedges et al., 1996) indicates an earlier, Cretaceous
diversi®cation of modern mammal and bird lineages,
and emphasizes the major gaps in the fossil record.
Nearly complete specimens from north-eastern China
show that modern birds as a subclass (Ornithurae) have
existed since at least the Late Jurassic (Hou et al., 1996).
Similarly, recent studies in palaeontology (Chatterjee, 1998;
Forster et al., 1998; Stidham, 1998) and molecular sequencing
(Cooper & Penny, 1997) indicate that bird diversity is
much older than previously thought, with most or all of the
major modern orders present in the Cretaceous. For nearly a
century the orthodox school of evolutionary chronology has
been devoted to a virtual cult of the oldest fossil of a taxon
which is inferred, often implicitly, to have originated with it.
But in recent times gene sequencing has been undermining
this approach, despite the fact that the gene trees are often
calibrated using fossils to give minimum ages. These
molecular studies indicate that the fossil record is severely
¯awed and that a literal reading of evolutionary detail in it is
an unrealistic approach.
Coupled with the traditional chronological paradigm was
the Pleistocene refugium model, an idea proposed in the
1970 and 1980s to explain tropical diversity. In applying
the idea to New Guinea, it was suggested that during the
Pleistocene ice ages populations of forest birds were
fragmented on a large scale and only occurred in a relatively
small number of forest refugia. There are many problems
with this scenario. For example, a long pollen record from
the Amazon rainforest, the area for which the theory was
developed, indicated that there has been continuous rainforest
there for 40,000 years ± it was not fragmented during
the glacial maxima (Colinvaux et al., 1996). Likewise DNA
differences between sister species of North American birds
indicate a speciation history over the last 5 Myr, implying a
history ten times longer than that predicted by the Late
Pleistocene origins model (Klicka & Zink, 1997). Similarly,
in the Pseudomyrmex viduus (F. Smith) group of ants,
centred in the Amazon basin, the geographical ranges of
most species do not coincide with the proposed Pleistocene
forest refugia. Instead, phylogeny, biogeography and host
plant speci®city indicate that much of the diversi®cation
took place in the Tertiary (Ward, 1999).
Cracraft & Prum (1988) criticized the refugium theory,
and instead proposed a vicariance event (the rising of the
Andes) to explain birds with western Colombian ± upper
Amazonian disjunctions, supporting earlier ideas of Chapman
(1917) and Croizat (1958).
Recent evidence con®rms that the lineage of many Andean
birds and mammals differentiated well before the Pleistocene,
and probably even before the uplift of the Andes.
Many botanists and zoologists previously thought that
Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925

Biogeography of birds of paradise 919
species in the Andes evolved at most a few million years ago,
but DNA evidence from Thraupidae, Formicariidae, Emberizidae
and others shows lineages dating back 4±10 Myr,
again an order of magnitude older than previous estimates
(conference papers presented by J. Bates, J. Lundberg and S.
Hackett, reported in Moffat, 1996). Roy et al. (1997) also
concluded that the Pleistocene refuge theory cannot account
for speciation patterns in South American and African
lowland bird faunas, and that most of the speciation in
tropical lowland biotas occurred before the Quaternary.
Until recently the oldest fossil passerines known were
from the upper Oligocene (25 Ma), younger than the oldest
fossils of other extant bird orders, and so passerines have
usually been assumed to actually be a younger group.
However, molecular studies (Mindell et al., 1997) indicated
that passerines are basal to the other neognaths ± an
`unexpected' result. As a consequence, Mindell et al. noted
the possible signi®cance of recently discovered passerine
fossils from the Australian Eocene (54 Ma) (Boles, 1995,
1997), still rather young compared with Cooper & Penny's
(1997) estimate of a Cretaceous origin for the order.
These data are compatible with the terrane tectonics
explanation given here for the Paradisaeidae. Based on DNA
hybridization, Sibley & Ahlquist (1985) calculated a date of
18±20 Ma for the split between Manucodia and the other
members of subfam. Paradisaeinae, which is compatible
with Mayr's (1953) proposal that the family was isolated in
the New Guinea region in the early Tertiary.
Hybridism
Hybridism, past and/or present, is especially signi®cant in
the birds of paradise, which probably have more interspeci®c
and intergeneric wild hybrids than any other bird family
except Anatidae. Perhaps the whole family represents an
ancient hybrid swarm formed when New Guinea was still a
vast series of archipelagos and later becoming more or less
`®xed' geographically with the consolidation of the mainland.
The reproductive barriers among the populations have
remained poorly developed and are disturbed relatively
easily.
Recombination of characters, in addition to the development
of strict synapomorphies, has been an important
mode of differentiation among the birds of paradise. For
example, Frith & Beehler (1998) wrote that adult males of
Seleucidis combine characters of more bird of paradise
genera than any other, with `plumes of Paradisaea,
pectoral fan-like plume feathers of Epimachus, bill form
and plush chest `cushion' feathers like Ptiloris and
Paradisaea, iridescent purple and green of Astrapia and
Ptiloris, a buff tail and ventral barring like Epimachus and
Drepanornis (in immatures), black head in female plumage
as in Parotia and Lophorina, and a red iris as in
Epimachus. If this species were today known from only
one or two adult male skins it would probably be
considered a hybrid!'.
Many traded skins of birds of paradise described early on
as new species were relegated in the 1930s to `hybrid' status.
However, Iredale (1950), Gilliard (1969) and Fuller (1995)
have argued that at least some of the `hybrids' are indeed
distinct species which still await discovery in the wild. At
least one appears to have a coherent range distinct from that
of the putative parents: the twenty-®ve specimens usually
identi®ed as Cicinnurus magni®cus ´ C. regius are `predominantly
from north coastal of New Guinea' (Frith & Beehler,
1998), and a distribution map would be very useful.
Utilization and conservation
The people of New Guinea have always used the plumes of
birds of paradise for decorating themselves at ceremonial
shows and there was also a thriving international trade in
skins for the millinery business of the Western world until
this was stopped in the 1920s. Because of its beauty and
inaccessibility the blue bird of paradise, Paradisaea rudolphi,
was the most valuable species with one skin fetching
40 pounds (Gilliard, 1969). 80,000 adult males (mainly
P. raggiana, P. apoda and P. minor) were killed and
exported a year. The younger adult males do not have the
ornamental plumage and so are not hunted but they are
reproductively fertile, and this meant that the trade had little
if any effect on the population.
However, there is currently another, more serious threat
to the birds as many of the lower montane forests they
inhabit are under pressure from mining, logging and
agricultural development. The staple crop in montane New
Guinea, sweet potato (Ipomoea batatas (L.) Lamarck) is
intensively cultivated and will grow up to about 2400 m,
above the upper limit of most birds of paradise. Although it
was emphasized that birds of paradise are surprisingly
tolerant of some disturbance in the forest, they will not
survive its total removal. A list of the twelve `rarest and most
threatened birds' in PNG (Beehler, 1993) included two birds
of paradise (Epimachus fastuosus and Paradisaea rudolphi)
and two bowerbirds [Archboldia papuensis Rand and
Sericulus bakeri (Chapin)]. In their list of globally threatened
bird species, Collar et al. (2000) cited Epimachus fastuosus,
Parotia wahnesi and Paradisaa rudolphi as Vulnerable, and
eight other birds of paradise as Near Threatened. Several
races are also possibly threatened, such as the bowerbird
Chlamydera l. lauterbachi Reichenow, which along with
endemic plants such as Lauterbachia Perkins (Philipson,
1986) is known only from the mid-Ramu Valley, near the
site of a proposed large-scale nickel mine.
CONCLUDING DISCUSSION: CONCEPTS
OF DISPERSAL, AND TECTONICS
Concepts of dispersal are central to interpretations of
evolution. Frith & Beehler (1998) speculated as to why
some widespread populations of birds of paradise have
differentiated into a series of regional forms, whereas
others have not. They assumed this to be at least partly
related to the age of the group. It is true that regional
vicariants are almost certainly of geological age, whereas
the distribution of a widespread form quite undifferentiated
Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925

920 M. Heads
throughout, say, Melanesia and Australasia might be the
result of a recent range expansion. However, two endemic
genera, each found through the New Guinea mountains,
but one comprising different species and the other not, may
well be the result of the same phase of, for example, early
Tertiary evolution. Taxonomic diversity or distinctiveness
is proportional neither to the age of, nor the time involved
in, the group's origin.
The second factor Frith & Beehler cited in explaining why
some widespread birds of paradise are diverse is the dispersal
ability of local populations, although no examples are given.
The difference between groups that do speciate and those that
do not probably has more to do with the different genetic
potentials of the ancestral populations. To be expressed, this
potential may need to be exposed to a phase of geological
change and physiographic and ecological dynamism, for
example a period of orogeny or terrane accretion.
If the concept of dispersal/migration is de®ned broadly as
`any and all changes of position', it is clear that evolution
should be included as a key component of dispersal, as the
evolution of a form can by itself bring about the distribution
of the form. In periods of allopatric evolution dispersal as
physical movement can be replaced with a concept of
dispersal as evolution. In this view, evolution is not seen as a
morphogenetic and biogeographical radiation from a monophyletic
point centre of origin, and from a single, monomorphic,
ancestral species (or even a parent pair). Rather, it
is a process working on broad geographical and phylogenetic
fronts by phases of modernization (cf. Kerr, 1997) of already
widespread ancestral complexes. (Mayr, 1982; while not yet
accepting this Croizatian idea, regarded it as a `completely
legitimate hypothesis'.) This view implies that evolution
operates mainly by parallel development of characters,
which is clearly seen in the Paradisaeidae ± recombination
of characters in the genera has been referred to in Semioptera
and Seleucidis. In another case, Frith & Beehler (1998)
referred to the `remarkable phenomenon' of geographically
and morphologically parallel variation in the adult females
of Lophorina superba and Parotia carolae, with the western
populations of the two species being `extremely similar'
(Beehler et al., 1986). Parallel evolution of taxa (which may
be cladistically monophyletic, with `uniquely' derived characters)
means that descendant taxa can have the same range
as an ancestral taxon. The range of Paradisaeidae, for
example, could have been inherited more or less directly
from a preparadisaeid ancestral complex.
Naturally a degree of range expansion and contraction is
constantly occurring, and in certain periods many taxa enter
a phase of mobilism. This may have been the case in New
Guinea and New Zealand during the Oligocene marine
transgressions in downwarped basins where many new,
shifting coastlines became available for colonization. However,
there is no evidence of this being important for most
birds in geologically recent times. On the contrary, the
current distributions of the vast majority of New Guinea
birds, and all the birds of paradise and bowerbirds, seem to
be the result of a phase of modernization mainly involving
vicariant phylogenesis.
It is suggested that populations of birds of paradise,
sedentary forest dwellers with small home ranges but
tolerant of disturbance, have been caught in the dramatic
geological uplift and downwarping of different parts of the
New Guinea orogen, leading to speciation, distributional
breaks and disjunctions, and altitudinal anomalies. The
ancestral complex of Paradisaeidae, Ptilonorhynchidae and
other Corvinae may have included birds of the mangrove
and associated vegetation (back-mangrove, swamp forest,
drier secondary vegetation) some of which have been
stranded in central Australia following marine transgressions
(Ptilonorhynchidae) and others uplifted in New Guinea
during Tertiary orogeny (Ptilonorhynchidae and Paradisaeidae).
The entire sequence: mangrove ± subalpine forest is
occupied by Manucodia comrii.
Populations currently juxtaposed on very narrow terranes
or sets of terranes may not always have been so close
together, as the individual terranes may have travelled
hundreds or even thousands of kilometres before docking.
Furthermore, in New Zealand and New Guinea several
accreted terranes have been substantially narrowed by
subduction, faulting and erosion subsequent to their formation,
some to just slivers, and Landis & Blake (1987)
suggested that terranes hundreds of kilometres wide may
have disappeared from within the New Zealand region.
These vanished terranes would have supported living communities,
some of which would have transferred to
encroaching terranes and given rise to modern plants and
animals. The slight differentiation between Paradisaea r.
rudolphi and P. r. margaritae (Fig. 30), for example, may
indicate a deeper structure, a biological and geological faultline
where populations of the birds of one terrane have been
grafted onto the birds and landscapes of another.
Simply because a bird is widespread through New Guinea
on many terranes does not mean this is the result of dispersal
from one terrane to another after terrane suturing. The
taxon might have been widespread before the terranes came
together, as even if the terranes were hundreds of kilometres
apart they probably already shared some taxa. There are
many questions concerning the biogeographical relationships
among populations and taxa of terranes such as the
Jimi, Finisterre and Owen Stanley terranes, or between areas
on the craton such as the Mimika/Setekwa Rivers, and the
areas north of the craton.
Biogeographical analysis is not concerned primarily with
the terranes as strata, even less as centres of origin, but
rather as tectonic indicators. For example, the lithological
differences between the shelf sediments of the craton and the
deeper water sediments of the Aure Trough probably have
little direct effect on the vegetation, but the distinct tectonic
histories of the two regions as revealed by lithology and
structure are of great signi®cance.
Similarly, the currently exposed strata of intrusive and
metamorphic terranes were obviously not colonized by
plants and animals as they formed, as this happened beneath
the earth's surface. However, these rocks indicate phases of
revolutionary physiographical change during which plants
and animals had ample opportunity for evolution. Later, the
Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925

Biogeography of birds of paradise 921
underlying rocks have been revealed by erosion, and the
living populations redeposited down onto them.
Many authors have cited the dramatically shifting coastlines
of pre-New Guinea in the Tertiary and the effect this
would have had on biological evolution in the region. For
example, Flannery (1995) described the New Guinea mammal
fauna as `extraordinarily speciose' with 227 living and extinct
species (all the latter from Pleistocene or Pliocene sediments).
This number `seems inordinately high', but `doubtless the
archipelagic nature of New Guinea throughout much of the
Tertiary has presented an opportunity for speciation¼'.
On the other side of the Paci®c, the Andes are the classic
cordillera. Recent ideas on the structure of the Andes are
similar to those suggested here for the New Guinea orogen,
in particular the Andes are tectonically more complex than
previously thought, and J. Flynn (quoted in Moffat, 1996)
cited the importance of lateral, as well as vertical, movement
on faults. Flynn emphasized that `The Andes are not
homogeneous, biologically or geologically¼ There is no
such thing as ``the Andes''' (cf. Katinas et al., 1999). In a
similar way, neither New Guinea nor its avifauna are a
single entity but are the result of many separate terranes
being welded together and onto the Australian craton. The
great complexity of these geological and geomorphological
processes is re¯ected in the complexity of form and
behaviour in the birds of paradise and bowerbirds, and in
their major species diversity along the New Guinea orogen.
ACKNOWLEDGMENTS
Andy Mack and Deb Wright of the Wildlife Conservation
Society helped my work in many ways. I've enjoyed many
long discussions about New Guinea biogeography with
David Frodin and the late Lyn Gressitt. I'm also grateful to
Ilaiah Bigilale, Lyn Craven, Marie-Claude Lariviere, Ed
Scholes, Silas Sutherland, Janine Watson, and Mark Watson
for literature, data and discussion, B.A. Barlow, A.J. de Boer,
N. Collar, Alistair Hay, Chuck Landis, Peter Linder, the late
Dr F. Markgraf, Michael Parsons, Peter Stevens, B.C. Stone,
Wayne Takeuchi, and Peter van Welzen for sending their
reprints, Ray Forster for a set of Archbold Expedition
reprints, David Bickford and the crew for their hospitality in
Brisbane, and Armstrong Bellamy and Kapi Rau for introducing
me to the birds of paradise 20 years ago.
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78. Frogs of the Papuan hylid genus Nyctimestes. American
Museum Novitates, 1896, 1±51.
Zweifel, R.G. (1985) Australian frogs of the family Microhylidae.
Bulletin of the American Museum of Natural History,
182, 265±388.
BIOSKETCH
Michael Heads has taught biology at universities in Papua
New Guinea, Fiji, Zimbabwe and Ghana. In the early
1980s he acted as LeÂon Croizat's literary executor in
Venezuela and joined Robin Craw to form the New
Zealand school of panbiogeography (R.C. Craw, J.R.
Grehan & M.J. Heads, 1999. Panbiogeography: tracking
the history of life. Oxford U.P., New York). He is
interested in rainforest ecology and tree architecture and
recently carried out ®eld-work in Jamaica and the Cook
Islands. He is currently writing a book on the biogeography
of Africa.
Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925