Reproductive performance of a declining forest passerine in relation to environmental and social factors: implications for species conservation

Identifying factors influencing a species’ ecological niche and demography is a prerequisite for species conservation. However, our understanding of the interplay between demographic rates and biotic/abiotic factors is still poor for most species of conservation concern. We evaluated relevance of eight hypotheses relating to timing of breeding, temporal nest exposure, nest concealment, topography, tree structure, predation risk and disturbance, density dependence and weather for explaining variation in reproductive performance of the declining wood warbler Phylloscopus sibilatrix in northern Switzerland. Reproductive performance was monitored with cameras at 136 nests from 2010 to 2012 and was associated to temporal exposure, timing of breeding and concealment of nests. Daily nest survival was positively related to the number of grass and sedge tussocks, nest concealment and nest age. Clutch size and number of fledglings decreased, the later in the season a nest was initiated. Nest surv...明确影响物种生态位（ecological niche）与种群统计学（demography）特征的相关因素，是物种保护工作的前提条件。然而，对于多数受保护关注物种而言，学界对种群统计速率与生物/非生物因子（biotic/abiotic factors）间的相互作用仍认知不足。本研究以瑞士北部种群衰退的林柳莺（Phylloscopus sibilatrix）为研究对象，评估了8个相关假说的解释效力，这些假说分别围绕繁殖时序、巢瞬时暴露度、巢隐蔽性、地形、林木结构、捕食风险与干扰、密度制约以及气象条件，用于解释其繁殖表现的变异。2010至2012年间，研究人员通过相机对136个鸟巢的繁殖表现进行了监测，发现繁殖表现与巢瞬时暴露度、繁殖时序及巢隐蔽性显著相关。每日巢存活率与禾草及薹草丛的数量、巢隐蔽性以及巢龄呈正相关。窝卵数与出飞幼鸟数量会随着鸟巢繁育季启动时间的延后而减少。巢存活率……