[Migration dynamics of Grus japonensis in recent years spring and conservation of its habitat in Xianghai Nature Reserve].

A survey on the migratory Grus japonensis in Xianghai wetland was conducted in spring of 1997-2003, and the relationship between migratory dynamics of Grus japonensis and changes of wetland eco-environment was analyzed. The population of Grus japonensis in Xianghai was 32, 25, 64, 92, 72,59 and 14, respectively in the spring of 1997-2003. The smallest number was found in 2003, only 1 breeding pair, and the largest number was found in 2002, including 16 breeding pairs. The earliest year for Grus japonensis arrival was 2002 (March 12), and the latest year was 2001 (March 28). The earliest year for Grus japonensis laying eggs was 1998 (April 1), and the latest year was 2003 (May 10). Most cranes finished laying eggs in early April. The earliest day was 40 days earlier than the latest one. Among the seven years, the year when the distribution range of Grus japonensis was the widest was 2000, and the cranes mainly distributed in 15 sites, such as Fulaowunpao, Jiandipao, and so on. On the contrary, they distributed only in 2 sites in 1998 and 1 site in 2003. The number and the distribution range of Grus japonensis in 2000 were far larger than those in 1997, 1998 and 2003. The migratory dynamics of Grus japonensis changed with the water condition of Xianghai wetland in different years. Based on the characteristics of water eco-environment of Xianghai wetland, a strategy for protecting Grus japonensis by wisely using the flood resource was suggested.