The Research On Swan Goose Nest-Site Selection In Dalai Lake, Inner-Mongolia

In the eight selected districts (Dalai Lake, Erka, Huhenuoer, Gen River, Beier Lake, Wulanuoer, Ergun River upstream, Hui River),33 fixed monitoring points were set and the quantity and distribution of swan goose were investigated using method of fixed-point observation and line transects from April to May of 2008 and 2009 in the Hulunbeier area, Inner Mongolia. Nest site selection of swan goose was investigated in three selected districts (Huhenuoer, Gen River, Wulanuoer) from April to July of 2009. Nine ecological factors were selected to find whether there was selectivity when choosing nest sites using U test and T test. With the help of discriminant analysis, the major impact factor can be found. After that, the predictive model for the appearance of swan goose and ecological factors can be created using Logistic regression equation.1. The research shown that among these selected areas the total number of swan goose has reduced more than 1000 from the comparison of number of swan goose in 2009 and 2008, especially in the Wulanuoer, which has a sharply reduction about 2000 from the initial number 2139 down to 233. However, the population in Erka, Hui River, and Huhenuoer had increased.2. There were 56 nests found in these three areas and 65 comparison quadrats had been set at the same time. About 92.8% of these nests were located in the reed and swamp. Distance from water surface in the nest site quadrats (2.6±0.3m) was less than the comparison quadrats (5.3±0.4m), and the difference was significant (P<0.05). Area of water surface in the nest site quadrats (1578.6±194.3m2) was larger than the comparison quadrats (409.1±41.5 m2), and the difference was significant (P<0.05), Area of reed around the nest site in the nest site quadrats (128.5±22.8 m2) was larger than the comparison quadrats (34.4±3.5 m2), and the difference was significant (P<0.05),The height of reed in the nest site quadrats (1.8±0.1m) was larger than the comparison quadrats (1.4±0.1m), and the difference was significant (P<0.05). Distance from human disturbance in the nest site quadrats (293.8±47.8m) was larger than the comparison quadrats (18.1±2.6m), and the difference was significant (P<0.05). Density of reed (P<0.05) in the nest site quadrats (755.3±19.5/m2) was larger than the comparison quadrats (612.9±44.7/m2), and the difference was significant (P<0.05). Area of island, depth of water under the nest, and the cover of reed in the nest site quadrats had insignificance difference compared with the comparison quadrats. The nest site habitat choosing equation created by Logistic regression equationis:Logit(p)=9.761+28.272×A+ 3.877×B+2.777×C+1.189×D (A distance from human disturbance; B area of water surface; C area of reed, D height of reed). The model showed that the probability of nest site choosing for swan goose is in direct ratio to the distance from human disturbance, area of water surface, area of reed, height of reed.