Threatened Birds in the Eastern Himalayas
by Mike Crosby, from Oriental Bird Club Bulletin 23, May 1996.
The north-east of the Indian subcontinent lies at the crossroads of the Oriental Region. Tropical semi-evergreen and moist deciduous forests in the lowlands extend from here south and west into the subcontinent, and east into southern China and South-East Asia. Subtropical forests follow the foothills of the Himalayas to the west and extend into south-east China and northern South-East Asia to the east. In the plains of Assam, the wetlands and grasslands support a distinct group of birds, many of which range to the Gangetic plain in the west and the wetlands and grasslands of South-East Asia in the east.
Himalayan temperate and subalpine zone forests extend from northern Pakistan and adjacent Afghanistan through north-east India to south-west China, and at high altitudes alpine habitats support many birds characteristic of the mountains of central Asia.
This wealth of habitats is reflected in a wealth of birds, and this area probably supports the highest diversity of bird species in the Orient. It also has one of the largest concentrations of globally threatened birds in Asia. The principal threat is habitat loss, particularly of wetlands and grasslands on the plains, tropical lowland forests, and subtropical and temperate forests in the Himalayas. However, the conservation situation is far from clear. Regional workshops for South Asia and South-East Asia held during 1995 as part of the Asian Red Data Book Project (Bull. OBC, 21: 64) revealed that there is a general lack of information on the current status of both the birds and their habitats.
The eastern Himalayas have a distinctly different climate (and hence vegetation and avifauna) to the rest of the range, as they lie further to the south and have warmer mean temperatures and fewer days with frost, and generally have a much higher rainfall (12). They extend from the Arun-Kosi valley in eastern Nepal, through Bhutan, north-east India, south-east Tibet and northern Myanmar to north-west Yunnan in China, and are here taken to include the mountains which extend from Nagaland and Manipur in India south to the Chin Hills in Myanmar and the Chittagong Hills in Bangladesh. These mountains have been identified as an endemic bird area by BirdLife International (4,16), which supports 22 restricted-range bird species of which 19 are eastern Himalayan endemics.
There is considerable variation in ornithological coverage within the eastern Himalayas. Eastern Nepal (5) and Darjeeling (see OBC's Indian Birding Itineries) are relatively accessible and well known to birders. A major ornithological survey of Bhutan was carried out by Salim Ali and colleagues between 1966 and 1973 (although their full report has yet to be published, 1), and several subsequent studies have been carried out (3,6,7). Far less information is available from the large, mountainous Indian state of Arunachal Pradesh, where recent surveys have been carried out in Namdapha National Park (13) and other sites in the east of the state (8), and the observations of Pratap Singh from localities throughout the state are particularly important (14). There appears to have been little recent work on birds in the Indian states of Manipur and Nagaland, and most of Burma (Myanmar) has until recently been inaccessible to birders, although the changing situation there has allowed visits to Mount Victoria and elsewhere (Bull. OBC, 21: 72, 22: 57-59). There also appears to be little recent published information on Himalayan birds in south-east Tibet, but the work of the Kunming Institute of Zoology and others in the Gaoligongshan region of Yunnan has resulted in important new information (9,11).
The magnificent Ward's Trogon, Harpactes wardi, is a good example of the current state of knowledge of a typical bird of this region. It is endemic to the eastern Himalayas, apart from a disjunct population on Fan-Si-Pan in northern Vietnam, and is found in broadleaf evergreen forest between 1,500 and 3,000 m. It was historically reported to be locally common (15), but the only recent records appear to be of small numbers in eastern Bhutan1, (D. Bishop, in litt., 1994), Arunachal Pradesh (14) and north-west Yunnan (11). There is evidence for loss of habitat in parts of its range, but not enough information to assess the impact on its population with any degree of accuracy (8).
Many parts of the eastern Himalayas have always been difficult to visit for logistical and political reasons, but the development which threatens their habitats and birds is also making new areas accessible. A host of possibilities are available to those wanting to carry out ornithological research there. Little or nothing is known on the breeding and wintering ecology of many species, for example on their seasonal altitudinal movements. Work on vocalisations could lead to some interesting new discoveries or re-evaluations of species limits, as has happened recently in China (2) and Nepal (10). Some birders have already begun to take advantage of the new possibilities to visit this exciting region. BirdLife International would welcome unpublished records of the candidate threatened species listed below, which will be passed on to Red Data Book national coordinators in the region, especially if they are from poorly known sites. For conservationists, an important question is whether existing protected areas support populations of the rarer and more localised species, or whether new areas need to be located and protected. The challenge is to understand the ornithological riches of this unique area, and take the measures required for their long-term survival, before they begin to be lost.
Ali, S., Biswas, B. and Ripley, S. D. (in prep.). The birds of Bhutan. Rec. Zool. Surv. India, Occasional Paper No. 136: 1-263.
Alström, P., Olsson, U. and Colston, P. R. (1992). A new species of Phylloscopus warbler from central China. Ibis, 134: 329-334.
Clements, F. A. (1992). Recent bird records from Bhutan. Forktail, 7: 57-74.
ICBP (1992). Putting biodiversity on the map: priority areas for global conservation. Cambridge, U.K.: International Council for Bird Preservation.
Inskipp, C. and Inskipp, T. P. (1991). Birds of Nepal. Second edition. London: Christopher Helm.
Inskipp, C. and Inskipp, T. P. (1993a). Birds recorded in a visit to Bhutan in autumn 1991. Forktail 8: 97-112.
Inskipp, C. and Inskipp, T. P. (1993b) Birds recorded during a visit to Bhutan in spring 1993. Forktail 9: 121-142.
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Ma Shilai, Han Lianxian, Lan Daoying, Ji Weizhi and Harris, R. B. (1995). Faunal resources of the Gaoligongshan region of Yunnan, China: diverse and threatened. Environmental conservation 22(3): 250-258.
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Ripley, S. D., Saha, S. S. and Beehler, B. M. (1991). Notes on birds from the Upper Noa Dihang, Arunachal Pradesh, northeastern India., Bull. Brit. Orn. Club 111: 19-27.
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Stattersfield, A. J., Crosby, M. J., Long, A. J. and Wege, D. C. (in prep.). A global directory of endemic bird areas. Cambridge, U.K.: BirdLife International.
Appendix 1: Candidate threatened species which occur in the eastern Himalayas.
Manipur Bush-quail, Perdicula manipurensis, White-cheeked Partridge, Arborophila atrogularis, Chestnut-breasted Partridge, Arborophila mandellii, Satyr Tragopan, Tragopan satyra, Blyth's Tragopan, Tragopan blythii, Sclater's Monal, Lophophorus sclateri, Yellow-rumped Honeyguide, Indicator xanthonotus, Rufous-necked Hornbill, Aceros nipalensis, Ward's Trogon, Harpactes wardi, Blyth's Kingfisher, Alcedo hercules, Dark-rumped Swift, Apus acuticauda, Wood Snipe, Gallinago nemoricola, White-bellied Heron, Ardea insignis, Grey-sided Thrush, Turdus feae, Rusty-bellied Shortwing, Brachypteryx hyperythra, Beautiful Nuthatch, Sitta formosa, White-browed Nuthatch, Sitta victoriae, Brown-capped Laughingthrush, Garrulax austeni, Rufous-throated Wren-babbler, Spelaeornis caudatus, Rusty-throated Wren-babbler, Spelaeornis badeigularis, Tawny-breasted Wren-babbler, Spelaeornis longicaudatus, Snowy-throated Babbler, Stachyris oglei, Black-breasted Parrotbill, Paradoxornis flavirostris, Black-browed Parrotbill, Paradoxornis atrosuperciliaris, Rufous-headed Parrotbill, Paradoxornis ruficeps.