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

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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 ànomalies' 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 ànomalies' 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 às 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 ènigmatic' 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 ànomalies' (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 ùltimately 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 ànomalies' 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 Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925
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 ànomalies' 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 ènormous 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 àltitudinal 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 ùnexpected' 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 ìnvasion' 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 Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925
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Birds of paradise, biogeography and ecology in New Guinea: a review

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