Photographic Guide to the Birds of Southeast Asia. Morten Strange
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tall dipterocarp trees is the predominant vegetation type in the Philippines and in the Sunda subregion, including the Malay Peninsula and Borneo. It also grows with a slightly different tree composition in wet tropical parts of continental Thailand, Myanmar and Indochina where the term evergreen forest is often applied—please see Lekagul and Round (1991) for a more detailed explanation. In deciduous forest a majority of the trees shed their leaves during the dry winter months; this habitat type prevails in the northern drier and more seasonal subtropical areas. Although some species occur in both habitats there are also great differences in the respective avifaunas.
The terms primary and secondary forest have been used as defined in the Glossary. Secondary forest varies from low regrowth with few large trees remaining, to areas selectively logged decades back with many large trees remaining, or regrown forest, labelled mature secondary growth in this volume. Where canopies meet and form a continuous cover, even though some disturbance may have taken place, the term closed forest is sometimes applied. At the other end of the scale, where no large trees are left standing, the habitat is labelled scrub.
Forest changes composition with elevation, likewise does the associated avifauna. In the tropics this change is both profound and amazing. In the East Malaysian state of Sabah on Borneo it is possible to travel from the lowlands at Poring Hot Springs to the summit of Mount Kinabalu at 4,101 metres within a couple of days—a journey that has been compared to travelling overland from the Equator to the Arctic.
Very few birds occur across the whole altitudinal range. In fact most birds occur only in the lowland forest. A few are restricted to the extreme lowlands below 300 metres but many also move into the foothills or submontane elevations. At 900 metres elevation the composition of birds changes significantly as many different species can only be found in the lower and upper montane elevations. A few occur only in alpine habitats near the tree limit, which in the tropics is around 3,600 metres.
Therefore the altitudinal range of the bird is an important item of information. Where numbers are given, these are taken from our main sources of reference, sometimes rounded off to nearest the 100 metres. For a definition of the vocabulary used, please see Figure 5 (page 36).
Within the vast region covered by this book we have not found it appropriate to give specific directions to where a particular species can best be found. Only in a few special cases has this been done for species that in our experience are mainly reported from certain often-visited protected areas such as Khao Yai National Park in Thailand or Mount Kinabalu National Park in Sabah.
After a description of the habitat and preferred elevation, there follows a brief mention of where within the habitat the bird is likely to be spotted. Especially in the lowland tropical rainforest, birds are typically specialists and occupy narrow niches within the forest. A few families like flowerpeckers, sunbirds and leafbirds may have members that frequently move across all levels of the forest, but this is the exception. It is true to say that a barbet will never be found on the ground or a pheasant in the top of a tree.
We have followed Strange and Jeyarajasingam (1993) using terms describing the levels of the forest that are best illustrated as in Figure 6 (page 37).
Any relevant notes on feeding and breeding behavior follow at the end of this paragraph.
Distribution and status
The distribution paragraph gives the extralimital range of the bird using the terms defined under 'Area Covered' in this chapter. Only a few species occur worldwide and most are restricted to the Oriental region. A few do not fit into the faunal regions as defined here, but this is explained. For instance, the Red-wattled Lapwing extends outside the Oriental region, without really spreading into the main Palearctic region, so the generally recognised area Middle East has been used.
Where nothing else is mentioned the bird is sedentary. For some groups with many migratory species, such as shorebirds, raptors and warblers, sedentary status is sometimes mentioned for clarification to emphasise that the species is an exception to the rule. But usually this is not the case, since large families like babblers and pheasants simply have no migratory members at all. The status of migratory species is, however, always explained. The term 'nomadic' refers to a species that moves outside its breeding range when not breeding, but not in the predictable north—south route followed by migratory birds.
For a few species their extralimital range falls within the area defined. This region does not have many restricted range or endemic species, but there are some and these are labelled 'Southeast Asia only' for clarification. They include small distribution species such as the Puff-throated, Stripe-throated and Grey-eyed Bulbul, Black-headed Sibia, Green-eared Barbet and Bar-bellied Pitta.
Most other small distribution range species also occur in Indonesia, as is the case for almost all the Sunda subregion endemic species. Even those endemic to Borneo usually extend into Indonesian Kalimantan. Since the rest of the Sunda subregion (Kalimantan, Sumatra, Java and Bali) is covered in A Photographic Guide to the Birds of Indonesia, the reader is advised to consult these two volumes together to get the larger picture of the distribution of most Southeast Asian birds.
Sometimes for clarification the term 'Eastern Indonesia' is used. This collectively refers to that part of Indonesia, which lies east of Borneo and Bali, i.e. east of Wallace's Line, an area that may or may not be regarded as part of the Oriental region. Please see A Photographic Guide to the Birds of Indonesia for further information.
Some species, such as the Green Peafowl and Pied Bushchat, have a discontinuous distribution and occur only in northern Southeast Asia and again on some Indonesia islands, in effect 'jumping over' the humid Sunda subregion. Here maps do not provide the full picture and again it has been necessary to explain further in the text.
After the full stop this paragraph covers the bird's local distribution and status. Where part of the bird's distribution falls outside the area covered—in other words the large majority of species—this has been clarified by the expression 'in region... '. Region refers to the map on pages 2-3.
In general the wording is only meant as a supplement to the maps which are aimed at being self-explanatory. They have been drawn up using our references for source, but have been updated in a few instances according to the latest information published in Oriental Bird Club publications, please see Bibliography for details.
Figure 5: The tropical rainforest at various altitudes
A simple colour-code has been applied to the maps:
Where breeding populations are augmented by migratory birds during the winter, this is explained in the text. Winter here refers to the northern hemisphere winter months December, January and February, the actual migratory season for most birds lasts from September to April. A few migrants can in fact be met with in winter quarters almost all months of the year.
Most migratory birds in Southeast Asia arrive on the so-called East Asian Flyway, following either the Malay Peninsula or the Philippine archipelago south, as illustrated in Figure 7 (page 40), which has been modified after Sonobe and Usui (1993).
We are aware that other authors, such as Lekagul and Round (1991) use a more elaborate system of four colour codes to distinguish between migratory and sedentary residents, and between passage migrants and winter visitors. This was deemed impractical in our case as it would only lead to a false sense of accuracy if applied here.
Figure 6: Vertical levels of the rainforest
Since the maps are quite small it is not possible to accurately pick out Singapore, Hong Kong and Brunei. These areas are therefore mentioned specially in the text where appropriate, except for montane species which by definition will not occur in these lowlands.
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