Root-Bernstein Meredith, Fierro Andres, Armesto Juan, Ebensperger Luis A
Department of Ecology, Facultad de Ciencias Biologicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
BMC Res Notes. 2013 Dec 20;6:549. doi: 10.1186/1756-0500-6-549.
Birds are important mobile link species that contribute to landscape-scale patterns by means of pollination, seed dispersal, and predation. Birds are often associated with habitats modified by small mammal ecosystem engineers. We investigated whether birds prefer to forage on degu (Octodon degus) runways by comparing their foraging effort across sites with a range of runway densities, including sites without runways. We measured granivory by granivorous and omnivorous birds at Rinconada de Maipú, central Chile. As a measure of potential bird foraging on insects, we sampled invertebrate prey richness and abundance across the same sites. We then quantified an index of plot-scale functional diversity due to avian foraging at the patch scale.
We recorded that birds found food sources sooner and ate more at sites with higher densities of degu runways, cururo mounds, trees, and fewer shrubs. These sites also had higher invertebrate prey richness but lower invertebrate prey abundance. This implies that omnivorous birds, and possibly insectivorous birds, forage for invertebrates in the same plots with high degu runway densities where granivory takes place. In an exploratory analysis we also found that plot-scale functional diversity for four avian ecosystem functions were moderately to weakly correllated to expected ecosystem function outcomes at the plot scale.
Degu ecosystem engineering affects the behavior of avian mobile link species and is thus correlated with ecosystem functioning at relatively small spatial scales.
鸟类是重要的移动连接物种，通过授粉、种子传播和捕食作用影响景观尺度格局。鸟类常与小型哺乳动物生态系统工程师改造的栖息地相关联。我们通过比较鸟类在一系列跑道密度的地点（包括没有跑道的地点）的觅食努力，研究鸟类是否更喜欢在八齿鼠（Octodon degus）的跑道上觅食。我们在智利中部的林科纳达德迈普测量了食谷鸟类和杂食鸟类的食谷情况，并作为鸟类对昆虫潜在觅食的一种衡量方式，在相同地点对无脊椎动物猎物的丰富度和数量进行了采样。然后我们量化了斑块尺度上鸟类觅食导致的样地尺度功能多样性指数。
我们记录到，在八齿鼠跑道密度较高、有刺豚鼠土丘、树木较多且灌木较少的地点鸟类更快找到食物来源且进食更多。这些地点的无脊椎动物猎物丰富度也更高，但无脊椎动物猎物数量更低。这意味着杂食性鸟类以及可能的食虫性鸟类会在八齿鼠跑道密度高且发生食谷行为的相同样地中觅食无脊椎动物。在一项探索性分析中，我们还发现，四种鸟类生态系统功能的样地尺度功能多样性与样地尺度预期生态系统功能结果呈中度至弱相关。
八齿鼠生态系统工程影响鸟类移动连接物种的行为，因此在相对较小的空间尺度上与生态系统功能相关。
