Little-known Oriental Bird: Courtois's Laughingthrushby Hong Yuan-hua, He Fen-qi, Roland Wirth, David Melville, Zheng Pan-ji, Wang Xia-zhi,Wang Gui-fu and Liu Zhi-yong, from OBC Bulletin 38, December 2003. After seven years of effort, Courtois's Laughingthrush Garrulax galbanus courtoisi, hitherto only known from two museum specimens collected in 1919, was 'rediscovered' in 2000 at its type locality, Wuyuan, Jiangxi Province, China. Unlike most other Laughingthrushes studied to date, Garrulax galbanus courtoisi nests in loose colonies. More intriguing still, is that despite intensive survey efforts covering all types of habitats, the bird has so far only been found in stands of old village trees, which villagers in this part of China have protected for generations. Only some 150-160 surviving birds are known to date, making this taxon one of the rarest birds in the world. A bird whose survival up to now and well into the future may be dependent on a regional tradition of protecting old village trees. Efforts, both domestic and international, to rediscover Courtois's Laughingthrush, a subspecies of Yellow-throated Laughingthrush Garrulax galbanus, at its type locality have continued for years but have now finally shown some dramatic and positive results. Furthermore, data recently obtained on the status and breeding behaviour of this heretofore unstudied bird is demonstrating to us something more than mere taxonomy.
For the whole story of the discovery of the bird, a British topographical surveyor, Colonel Godwin-Austen, constitutes the very beginning. In 1874, Colonel Godwin-Austen described a new species of laughingthrush, Garrulax galbanus, based on skins he obtained in February 1873 in the Munipur valley, eastern Assam, India, (1) from which area the species is now mostly known by its English name, the Yellow-throated Laughingthrush. Later on, in 1923, M. A. Ménégaux, President of the Société Ornithologique de France, recognised another laughingthrush species, Garrulax courtoisi, based on two bird skins collected in September 1919 by a French missionary Père A. Riviere, from Wuyuan in south-east China and sent to him by Père F. Courtois. (2,3) And, although the direct distance from Munipur to Wuyuan is at least 2000 kilometres, and no record of either of the two birds had been reported at any site between the two localities at that time, courtoisi was nevertheless soon after relegated to the status of a subspecies of Garrulax galbanus. (4) More than half a century then passed before in 1982 two Chinese ornithologists, Prof. Cheng Tso-hsin and Tang Rui-chang, described one more subspecies of galbanus, and since the three specimens were collected at Simao in Yunnan Province, south-west China, the new subspecies was named simaoensis. (5) Therefore, three subspecies of the Yellow-throated Laughing-thrush have so far been recognised - the nominate form distributed in the area where the Indian sub-continent meets Indochina, and the other two in mainland China. Although Simao lies more or less between Munipur and Wuyuan, it is apparent that the Yellow-throated Laughingthrush shows a completely allopatric pattern in the ranges of its three subspecies. (6,7) It is now known that the nominate form, whose type locality is Munipur, can also be found in a relatively large surrounding area, including the Chin Hills of western Myanmar (Burma) and also as far afield as a small area in southern Bangladesh. (8,9) According to Smythies, it is locally 'a common breeding bird of the Chin Hills at 5,000-6,000 feet from mid-April to early June'. (10,11) In contrast, nothing new came to be known of either a geographical or ethological nature about the two Chinese subspecies. In fact, until our recent success, no-one, neither professional ornithologist nor keen bird watcher, had reported having so much as seen a courtoisi or simaoensis, whether in their type localities or elsewhere, since the type specimens were collected in 1919 and 1956, respectively. This implied that they were restricted to a rather small area, and/or in a rather specific habitat, and/or had been reduced to very small surviving numbers - all of which have proven to be true for courtoisi. Simaoensis has yet to be rediscovered. It should be noted, however, that their elusiveness in the wild notwithstanding, there are several populations of Yellow-throated Laughingthrush in European collections, which apparently are self-sustaining, (11) and some bird keepers believe that the birds they have are of the subspecies simaoensis. (12) If the birds are simaoensis, it is far from clear how they could have reached Europe, and from whence they came. An exhaustive search of all original customs documents relating to passerine birds exported from China revealed no record of Yellow-throated Laughingthrush. When, in the early 1990s, concern as to the status of the two forms of the bird occurring in mainland China grew, the German conservation organisation Zoologische Gesellschaft fur Arten und Populationsschutz (ZGAP) provided some small grants to their Chinese colleagues to investigate the status of wild populations of the bird, hopefully including both courtoisi and simaoensis. It required successive field surveys over a period of seven years before courtoisi was finally rediscovered in the wild in Wuyuan, Jiangxi during the 2000 breeding season. During our field observations in 2000, a total of 80-90 birds was counted, which were found in two breeding flocks approximately 40 km apart. Although we obtained some basic ethological knowledge and a rudimentary understanding of the breeding biology and habitat selection of the bird, all we could really say about the current status of this taxon was that it was extremely rare, leaving many uncertainties. However, following fieldwork in 2001, when two more breeding sites of courtoisi were found, a relatively more integrated picture has emerged, making it possible to outline, even if still only sketchily, the breeding range and status of the bird in Wuyuan County. Briefly, the birds are found at an altitude of less than than 100 m, breeding in flocks, choosing their breeding sites close to a river, nesting in the canopy of big trees, and all four breeding flocks found to date are situated around villages, and very close to villagers' houses. This close association between the birds and human habitation is remarkable. It is well established that most laughingthrushes nest in bushes, shrubs, or tall grasses rather than large trees, and breed in relatively isolated pairs rather than colonies, as indeed is reported for nominate galbanus. (13) But courtoisi seems to confound all that we thought we knew about laughingthrushes. In fact, although we had thought we had surveyed all the potential habitats available for this laughingthrush in Wuyuan County in previous years, we failed to find any trace of the bird. However, while we were counting and identifying the large, old trees occurring around villages in 2000, the bird was suddenly and very surprisingly, right in front of us! In our 2001 field season, more than 20 courtoisi nests were located, and all of them were sited in the canopy of mature trees. The trees the birds mostly favour as nesting sites are the Chinese Sweet Gum Liquidambar formosana/taiwaniana and the Camphor Cinnamomum camphora, while others include Pterocarya stenoptera, Aphananthe aspera, and the conifer Cunninghania lanceolata. It therefore appears that these centuries-old large trees are providing crucial, if not indeed obligate, habitat for the continued successful reproduction of this rare bird. Geo-morphologically, Wuyuan County's landscape consists mainly of montane areas rising from 35 m at the base of hills to over 1,600 m at the mountain tops. The small basins and plains lower than 200 m are quite heavily populated. Today over 70% of the county is still covered by forests and woods, albeit these are rarely original but rather secondary forest or even plantations. It can be safely inferred that in the past there were much more extensive primary sub-tropical evergreen forest and wood communities present. It appears that Courtois's Laughingthrush needs large, mature trees which formerly must have been common, as presumably was this taxon. Considering other features of the breeding habitats that courtoisi seems to require, such as a low altitude and proximity to a river, the conclusion might be drawn that, in present times in Wuyuan, only the outskirts of villages can satisfy all of the species's requirements. |
