Resources Investigation, Migratory Dynamics Of Charadriidae And Breeding Ecology Of Common Tern And Little Tern In Wuliangsu Lake Wetland

The Wuliangsu Lake nature reserve is located in Urad Front Banner. It was built in 1995 and was promoted to Inner Mongolia nature reserve in 1998. Wuliangsu Lake is the eighth largest fresh water lake in China, and it is the also the second biggest lake in Inner Mongolia. Because it was located in semi-desert area and was the biggest nature wetland in the same latitude, so it played an important role in world wetland research, molting of Ducks and Geese and the birds'migration. In recent years, Wuliangsu Lake changed to desert gradually because of water pollution and environment change, such as rainfall reduction, climate warming.Some investigations on bird resources were done in 1980s, mainly in the species composition and distribution. But in recent years, there has been no longer systematical investigation about bird resources. Bird migration status was a blank in Wuliangsu Lake for a long time. In reproduction, only a few species were researched in Wuliangsu Lake, and there have not been reproduction reports on Common Terns and Little Tern.From March to November in 2009, the route line transect method was used to investigate the migratory time, maximum number of clusters and the peak of migration of Charadriidae in spring and autumn. During the breeding season, reproductive behavioral ecology of Common Terns and Little Tern was observed such as mating, nesting, egg-laying, incubation, rearing and so on. The results were as follows:(1) There were 53 species of Charadriidae in Wuliangsu Lake, in which 18 species were summer residents, and 35 species were travelers. 8 species were widespread species, and 45 species were Ancient North.4 new species were recorded, they were Phalarpus lobatus,Calidris alpina,Rissa tridactyla,Limosa lapponica . (2) 40 species were recorded in this survey; they all belonged to summer residents or travelers. We did an annual observation and obtained seasonal dynamic. Some moved to Wuliangsu Lake as early as the end of February, and spring migration peak occurred in April and May. June and July was autumn migration peak. Most of Charadriidae began to migrate to south in September and almost all left Wuliangsu Lake by the end of October.(3) Study on the reproduction ecology of Common Terns and Little Tern were carried out in Wuliangsu Lake. Common Terns and Little Tern arrived at Wuliangsu Lake between late April and early May. The reproduction period was from May to July. Clutch size of a Common Tern and Little Tern was mainly 3 eggs. Incubation of Common Terns was 24-26 days. Nestlings'food was mainly fish, and could walk on the day when they hatched out and it took around 26 days before they began to fly. Incubation of Little Terns was 19-22 days. It took around 26 days before they could fly. In mid-September, Common Terns clustered and migrated to south to winter. More than ten thousands of Common Terns were seen in Gesuer on 12th September. The latest time we saw Common Terns was on 6th October. They stayed in Wuliangsu Lake more than 160 days; Litter Terns clustered and migrated to south to winter in latter August, we saw hundreds of Litter Terns on 26th August in Sishagedan. The latest time we saw Litter Terns was on 6th September. They stayed in Wuliangsu Lake more than 120 days.According to the above study and investigation, we summarized the problems that the Wuliangsu Lake faced. Such as water pollution seriously influenced the lives of waterfowl and aquatic animals, traditional fishing threatened the life of waterfowl, and fish species were single and the number decreased rapidly. We proposed the conservation measures according to these problems.