The Ratio of Adult and Juvenile on BlackHeaded Gull Wintering in Dianchi Lake of Yunnan

By the methods of catching and photographing to get the bird’s sample, we analyzed the percentage of juvenile Blackheaded Gull in 3 areas of Dianchi Lake. Sampled and Blackheaded Gull banding was carried at Haigeng dam of Dianchi Lake. During January 2011, January and February 2012, December 2012, and March 2013, we captured 131、339 and 475 gulls, respectively. Photo sampling carried at Green Park, Haigeng Dam and Baiyukou in January, February and December of 2013. Every season and every site, there 1000 birds were pictured. With consulting a lot of data, the percentage of juvenile Blackheaded Gull in Dianchi Lake and population quantity were investigated. The result showed that, in the periods of 2010, 2011, 2012and 2013 wintering, ratio of Juvenile was 237%, 336%, 489%, 431%, respectively. Among them, the ratio of Juvenile was increased significantly. Moreover, population quantity had maintained increasing, especially in 1992、2002、2010, the increase was jumped. Base on the ration of juvenile and increase regulation of population quantity, we predicted the population of Black headed Gull wintering in Dianchi Lake would be increased greatly in next a few years.