Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Ecol Lett. 2010 Mar;13(3):311-20. doi: 10.1111/j.1461-0248.2009.01423.x. Epub 2010 Jan 21.
Herbivores forage in spatially complex habitats. Due to allometry and scale-dependent foraging, herbivores are hypothesized to perceive and respond to heterogeneity of resources at scales relative to their body sizes. This hypothesis has not been manipulatively tested for animals with only moderate differences in body size and similar food niches. We compared short-term spatial foraging behavior of two herbivores (sheep and cattle) with similar dietary niche but differing body size. Although intake rates scaled allometrically with body mass (mass(0.75)), spatial foraging strategies substantially differed, with cattle exhibiting a coarser-grained use of the 'foodscape.' Selectivity by cattle (and not sheep) for their preferred food was more restricted when patches were smaller (< 10 m(2)). We conclude that differences in spatial scales of selection offers a plausible mechanism by which species can coexist on shared resources that exhibit multiple scales of spatial heterogeneity.
食草动物在空间复杂的生境中觅食。由于异速生长和尺度依赖的觅食，食草动物被假设能够感知和响应与身体大小相对应的资源异质性。对于身体大小差异不大且食物生态位相似的动物，这一假设尚未经过操纵性测试。我们比较了两种食草动物（绵羊和牛）的短期空间觅食行为，它们的食物生态位相似，但体型不同。尽管摄入量与体重呈异速生长（质量的 0.75 次方），但空间觅食策略却有很大差异，牛表现出对“食物景观”更粗糙的利用。当斑块较小时（<10 m(2)），牛（而不是绵羊）对其偏好食物的选择性受到更严格的限制。我们的结论是，选择的空间尺度差异为物种如何在具有多种空间异质性尺度的共享资源上共存提供了一个合理的机制。
