关键词: 云南, 鹭类, 繁殖地, 生态位宽度

Abstract:

Human disturbance on wildlife is frequently mentioned as one of the principal issues of concern in biodiversity
conservation, and it is extremely important to identify accurately what human activities adversely impact the wildlife. Nest trees
pruning destroyed the egret breeding sites, and it is unknown how the egrets responded to the destroyed nest trees. A follow-up survey
was taken to compare the community composition, duration time of breeding activity, and nest space segregation between old and new
colony sites in Dali, Yunnan, China. It was found out that a sole black-crown night heron Nycticorax nycticorax population newly
occurred; the duration time of breeding activity was prolonged. For the mixed- species colony, the nest niche breadth figures in
horizontal, vertical direction and the distance to trunk of black-crown night heron increased, while which of the latest arrived cattle
egret Bubulcus ibis decreased. The results showed the egrets in new colony site faced bigger breeding pressure, which made the
breeding efficiency decreased. It was suggested that the pruning to the egrets nesting trees should be done cautiously and avoid drastic
pruning.

Key words: Yunnan, egrets, breeding sites, niche breadth