5IUCN Red List Categories (Version 3.1). Prepared by the IUCN Species Survival Commission. World Conservation Union, Gland, Switzerland and Cambridge, UK,2001.
6BirdLife International. Threatened birds of Asia: the BirdLife International red data book. BirdLife International, Cambridge,2001.
7Simon Delany, Derek Scott. Waterfowl population estimates (3rd edition)[M].Wetlands International, Global Series No. 12, Wageningen, The Netherlands,2002.
8Alerstam T, Hedenstrom A. 1998. The development of bird migration theory[J]. J Avian Biol, 29:343-369.
9Dunbar RIM. 1998. Impact of global warming on the distribution and survival of the Gelada Baboon:A modelling Approach[J]. Global Change Biology, ( 3 ) : 293 -304.
10McNeil R, Cadieux F. 1972. Fat content and flight range capabilities of some adult spring and fall migrant North American shorebirds in relation to migration routes on the Atlantic Coast [J].Naturaliste Canadien, 99 : 589-606.
