西藏雅鲁藏布江中游斑头雁的越冬种群数量、分布和活动区

Population,distribution and home range of wintering bar-headed goose along Yaluzangbu River,Tibet

斑头雁(Anser indicus)是高致病性禽流感病毒的易感鸟类和潜在的传播源,在禽流感防控中占有重要地位。有关斑头雁的越冬种群现状缺乏研究。2009年1月,在雅鲁藏布江中游共统计到越冬斑头雁44657只,主要分布于一江两河地带的林周县、日喀则市、白朗县、拉孜县、江孜县和贡嘎县境内。这一统计数据远高于1990年代的统计数量,由此可将其全球种群数量估计值由5.2-6万只修正为至少7万只。越冬斑头雁的平均集群大小为(208±262)只(n=215),主要栖息环境包括冬小麦田、冬歇期农田、河流湖泊和沼泽湿地,其中在冬歇期农田中统计到的数量占72.1%。2006-2008年,对青海湖繁殖斑头雁的卫星跟踪表明,其越冬地点主要位于西藏雅鲁藏布江流域、拉萨河流域和印度,越冬期为11月至翌年的3月份,在越冬地平均停留(108±30)d,越冬活动区大小为(122.22±124.94)km2(n=3)。受西藏独特的宗教传统和农耕畜牧结合的生产方式的影响,越冬斑头雁经常与大量家畜和水鸟混杂在农田觅食,在禽流感疫情防控时应引起重视。

Bar-headed Goose Anser indicus is a large waterbird mainly inhabiting on plateau and migrating across a large geographic area.Understanding its biology and ecology is very crucial in prevention and control of avian influenza because this species is highly susceptible to and a potential transmitter for HPAI.Many studies have been carried out on this species at Qinghai Lake,a breeding ground,since the outbreak of HPAI on this species in 2005.Status of the wintering population of this species in Tibet,however,has not been documented well,although Yaluzangbu River basin of Tibet is one of the most important wintering areas in China.A population survey was conducted in this area in January,2009,and 44657 Barheaded geese were recorded,mostly in Linzhou,Rikaze,Bailang,Lazi,Jiangzi and Gongga,accounting for 22.8%,21.9%,11.8%,11.2%,9.7% and 7.2% of the total number sighted,respectively.This number greatly exceeds 10081 Bar-headed geese surveyed in the same area in 1990s.Based on this survey and data of other wintering grounds,we estimated a current world population of at least 70000,comparing to 52000-60000 documented by the Wetlands International in 2002.The population distribution mainly depended on the availability of feeding areas,indicating food may be the most important factor for wintering Bar-headed goose.Winter habitats included winter wheat field,winter idle cropland,rivers lakes,and marsh,with 72.1% of the total observations recorded in winter idle cropland.Bar-headed goose spent the majority of time to feed in winter idle cropland and winter wheat field,and rested in rivers and lakes at noon and night.The flock size differed significantly among the four habitats,with the average of（208 ± 262）（n = 215）.Ten Bar-headed Geese were satellite tracked from Qinghai Lake from 2006 to 2008,three of whom successfully arrived at their wintering ground in Yaluzangbu River and Lasa River basins in Tibet of China,and Kohima of indian.The satellite tracking,together with traditional banding recovery outcome,reveals a close connection between the wintering population of these areas in Tibet and the breeding population at Qinghai Lake,therefore a high release risk of HPAI from Qinghai Lake may exist.Bar-headed geese spent（108 ± 30） days（n = 3） from Nov.to next Mar.in wintering ground,with the overall home range size of（122.22 ± 124.94） km^2（n = 3）.The last stopover in fall migration was（103 ± 63） km（n = 3） away from the wintering ground,where the geese spent（14 ± 5） days（n = 3）.In the same area,a large number of other waterbirds,including Ruddy Shelduck Tadorna ferruginea,Black-necked Crane Grus nigricollis,Mallard Anas platyrhynchos,Red-crested Pochard Rhodonessa rufina,and Common Pochard Aythya ferina,mostly HPAI H5N1 susceptible,were often seen feeding together with Bar-headed Geese.The Buddhism religion by the Tibetan people who expresses belief in the sacredness of all living creatures,in the wintering ground has contributed well to the conservation of wildlife.The combined crop farming with livestock grazing on the same agricultural areas,however,results in domestic animals commonly mingling in a feeding flock of Bar-headed Geese or vice versa in Tibet,increasing avian influenza virus transmission between them.Minimizing or totally stopping waterfowl-poultry livestock-Human contact would be essential in HPAI surveillance and prevention.