Dynamics of bird assemblages in response to temporally and spatially variable resources in arid Australia

Bird assemblages in arid Australia are often characterised as being highly variable through time in response to boom and bust dynamics, although the importance of habitat in structuring assemblages at a local scale is also recognised. We use a novel approach to investigate the importance of rainfall variability in structuring bird assemblages in a resource-limited environment. Monthly bird surveys were conducted at ten plots for eight years at a botanical and zoological park in central Australia, including five irrigated plots within a fenced area and five natural plots outside. Irrigation – used to promote growth, flowering, and fruiting of plants – created an artificial resource-enhanced environment against which the response of birds to natural fluctuations in season and rainfall were compared. Species richness was generally maintained at a higher level in resource-enhanced plots during dry times but was higher in natural sites when rainfall was high, mainly due to increases in grani...

澳大利亚干旱区的鸟类群落通常被认为会随种群盛衰动态呈现高度的时空变异性，但学界也已认可栖息地在局域尺度上塑造鸟类群落结构的重要作用。本研究采用新颖的研究范式，探究资源受限环境中降雨变异性对鸟类群落结构的调控效应。研究团队于澳大利亚中部一座动植物园内，针对10个样地开展了为期8年的月度鸟类调查，其中围栏封禁区域内设置5个灌溉样地，外围原生区域则设置5个天然样地。灌溉措施旨在促进植物的生长、开花与结实，由此构建了人工资源富集的生境，以此对比鸟类在自然季节波动与降雨变化下的群落响应差异。整体而言，干旱时段资源富集样地的物种丰富度（species richness）通常维持在更高水平；而当降雨充沛时，天然样地的物种丰富度则更高，这主要归因于食籽类（grani...）类群的种群扩增。