Nest site characteristics of three heron species in Wuhu and adjacent regions

The nest site characteristics of little egret (Egretta garzetta), black-crowned night heron (Nycticorax nycticorax) and Chinese pond heron (Ardeola bacchus) were studied by collecting samples from four heronries in Wuhu and adjacent regions in 2005. Eleven nest-site variables, i.e., nest tree species, nest height, nest tree height, coverage above nest, coverage of 1 m around nest, diameter of nest tree at breast height, distance of nest from tree center, diameter of nest branch, distance of nest to heronry edge, slope location, and altitude, were measured, and the nest site characteristics of test heron species were analyzed by the methods of one-way analysis of variances and principal component analysis. The results showed that the main components better described the nest habitats were nest site, nest tree, protection, and slope location, with the contribution rate being 25.51%, 24.42%, 13.19%, and 12.32%, respectively, and the major factors affecting the nest-site selection of test herons were microhabitat fitness and predation pressure.