Three-dimensional niche partitioning between two colonially nesting ardeid species in central China  

作　　者：Yuanxing Ye Canshi Hu Yiting Jiang Geoffrey W.H.Davison Changqing Ding 

机构地区：[1]School of Ecology and Nature Conservation,Beijing Forestry University,Beijing 100083,China [2]College of Life Science,Guizhou University,Gui-yang 550025,China [3]Department of Life Science,Liaoning University,Shenyang 110036,China [4]National Biodiversity Centre,National Parks Board,Singapore 259569,Singapore

出　　处：《Avian Research》2021年第3期338-345,共8页鸟类学研究（英文版）

基　　金：supported by National Natural Science Foundation of China(Nos.31772483 and 31372218 to CD,No.31900371 to YY).

摘　　要：Background:Interspecific competition is known to be strongest between those species that are both closely related and sympatric.Egrets are colonially nesting wetland birds that often overlap and can therefore be expected to compete in roosting and nesting habitat as well as in diet.According to the niche partitioning hypothesis,it is to be expected that these similar species would show differentiation in at least one of the main niche dimensions to reduce competition.We tested niche partitioning between the colonially nesting Little Egret(Egretta garzetta)and Cattle Egret(Bubulcus ibis)in temporal,spatial and trophic dimensions.Methods:Field study was conducted in three mixed egret colonies in Yangxian County,southwest Shaanxi Prov-ince,central China.For each nest colony we recorded its spatial location,the height of nesting trees and of nests,the height of roosting trees and of roosting individuals within the trees.We determined the first egg-laying and first hatching dates of the two species.Craw dissection of storm-killed egret nestlings was used to measure the diet.Six transects were surveyed to study foraging habitat selection.Results:We found that hatching time of Little Egrets peaked earlier(by about 1 month)than that of Cattle Egrets.Cattle Egrets nested and roosted higher than Little Egrets.The foraging habitats used by Little Egrets were dominated by river banks(73.49%),followed by paddy fields(13.25%)and reservoirs(10.84%),whereas Cattle Egret foraging sites were characterized by grasslands(44.44%),paddy fields(33.33%)and river banks(22.22%).Little Egrets consumed more fishes(65.66%)and Odonata larvae(13.69%)than Cattle Egrets,while Cattle Egrets were found feeding mainly on Coleoptera(29.69%)and Orthoptera(23.29%).Little Egrets preyed on larger mean biomasses of food items than Cattle Egrets.Conclusions:Our results confirm the niche partitioning hypothesis as a mechanism for coexistence among ecologi-cally similar species.In two coexisting egret species,niche partitioning is multidimensional,such that

关 键 词：Bubulcus ibis Egretta garzetta Interspecific competition Niche partition Sympatric species 

分 类 号：Q958.1[生物学—动物学]