陕西红碱淖同域分布遗鸥与棕头鸥巢址选择比较

2009—2011年4—7月在陕西红碱淖对同域分布的遗鸥和棕头鸥巢参数特征、巢群空间分布和巢址生境选择进行了对比分析。结果表明:巢外径、巢深、巢高等参数均存在显著差异,这主要是与营巢生境和巢址空间分布上有关;从巢群空间分布上来看,两者均选择于湖心岛上营巢繁殖,巢群呈斑块状分布,但彼此没有混巢现象,有时甚至通过压缩种间巢间距来达到共存,由于遗鸥繁殖群体数量占优势,遗鸥总是占据最佳的巢域,棕头鸥巢群通常被排挤至湖心岛边缘部分;在巢址生境选择上,植被类型、植被高度、植被盖度、巢离水面高度和巢距最近水边距离均存在显著差异。这表明两者巢址生境选择上具有特异性,这种特异性使得巢址生境选择上存在生态位差异,促成了遗鸥和棕头鸥能在同一湖心岛上营巢繁殖因素之一。

Nest site selection by sympatric relict gull and brown-headed gull in Hongjiannao of Shaanxi Province, Northwest China

A comparative study was conducted on the nest-site parameters and nest spatial distribution patterns of sympatric relict gull(Larus relictus) and brown-headed gull(Larus brunnicephalus) in Hongjiannao of Shannxi Province from April to July,2009 and 2011,aimed to understand the characteristics of the nest-site selection by the two gull species in the study area.There existed significant differences in the nest outer diameter,depth,and height between the two species,which was mainly related to the nest-building habitat and the spatial distribution of nest site.The nest spatial distribution of the two gull species was in patchy.Though the two species selected islets to build nests for breeding,no nests were mixed each other.The coexistence of the two species was achieved by reducing their nest spacing.Due to the superiority in breeding population,relict gull occupied the optimal territories for nest-building,while brown-headed gull was pushed aside to the edge of the islets.For the selection of nest site,there existed significant differences in the demands of vegetation type,its height and coverage,height above water surface,and the shortest distance to water edge between relict gull and brown-headed gull,suggesting the nesting niche segregation,which made the two gull species possible to build nest and breed on the same islets at the same time.