Nest Site Selection Of Grey Herons During The Initial Stages Of Wetland Recovery In Zhalong Natural Reserve

Grey heron is one of representative bird, and approved indicator species to wetlandecological environment. Because of successive year's drought or fire from 1999, ZhalongNatural reserve beginning to successive year's irrigation from 2002.Investigator use the survey methods of fixed-sopt observation, GPS positioning, factormeasurement to survey the ecological factors of Grey herons' nest site and non-nest site habitatin Zhalong Nature Reserve from march to may in 2004 to 2006.It is foundthat all of the nests of Grey herons are located in reed marsh, showed the highspecificity of Grey herons to reed marsh. The result of variance analysis indicates that nest-sitehabitat of Grey herons is specific and non-randomicity.The consequence of Mann-Whitney U test shows that the ecological factors water depthunder nest (p＜0.01), distance to lower frequency human activity area (p＜0.01), distance to highfrequency human activity area (p＜0.01), vegetation density (p＜0.01) have significant variance,and vegetation height (p＜0.05), vegetation coverage (p＜0.05) have no variance between nestsite habitat and non-nest site habitat.The result of principal components analysis shows water depth, lower frequency humanactivity area, vegetation density compose the essential factor of deciding the nest site selectionof Grey herons, and distance to high frequency human activity area, vegetation height,compose the second principal component, disturb factor, then vegetation coverage was defiedas cover factor.Using logistic regression method gained the logistic regression model of nest site habitatselection, namely P=1／(1+e^{1.764-0.002X₁-0.04X₂+0.004X₃}.Establishment of habitat assessment model, the results of Grey herons nest-site habitatassessment in 2004-2006 are HSI₂₀₀₄=0.6593, HSI₂₀₀₅=0.6869, HSI₂₀₀₆=0.6884. The resultsindicate that since successive years irrigating, the nidificant habitat quality of Grey heron werestable and improved year after year.The method of distributed distance index was used to study the spatial patterns of nests onGrey herons, and the distributed distance indexes of 2004-2006 were I₂₀₀₄=5.4148,I₂₀₀₅=5.2309, I₂₀₀₆=7.1717, shows that the nest of Grey herons is clumped dispersion, andexists the trends of the clumped degree increase and stiitable nest-site of Grey herons expend.