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

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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 Àustralo-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, ènough 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 àre 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 èxtremely sedentary'. Similarly, the mountains of the Papuan Peninsula, SE New Guinea (mainly Owen Stanley and Bowutu terranes) also ìnexplicably' (Diamond, 1972) lack several montane birds of paradise that are present throughout the rest of the New Guinea cordillera (Loboparadisaea Rothschild, Pteridophora Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925
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 ìnexplicable' because an unrealistic concept of dispersal is being used: for the same reason, the absence of woodpeckers and trogons from New Guinea is àlmost 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). 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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