How do frugivores track resources? Insights from spatial analyses of bird foraging in a tropical forest
How do frugivores track resources? Insights from spatial analyses of bird foraging in a tropical forest
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食果动物如何追踪资源？
作者：
J. Saracco;J. Collazo;M. Groom
食果动物经常密切跟踪成熟的水果丰富的地方，尽管这种资源的短暂和典型的斑块分布。我们使用空间自相关和互相关分析，以量化的空间格局的水果丰富度和鸟类frugivory在4个月内的森林4.05公顷的研究网格在波多黎各。分析的重点是两个tanager物种，Spindalis portoricensis和Nesospingus speculiferus，和他们的主要食物植物。三个广泛的问题是解决：（1）在什么样的空间尺度是水果丰富和食果类斑块;（2）在什么样的空间尺度食果类水果丰富的反应;（3）在何种程度上食果类鸟类之间的空间格局重叠？水果补丁大小，物种组成，异质性是可变的几个月之间，尽管水果补丁的位置保持相对一致的几个月之间。食果动物和水果丰富度之间的正相关表明tanagers成功地跟踪水果丰富度。然而，食果性比水果丰富性更加局部化。尺度的空间重叠在frugivory和每月变化的觅食地点的两个tanager物种表明，种间促进可能是重要的，在确定鸟类觅食的位置。特别是S.一种专门的食果动物，可能依赖于群居的通才N。speculiferus，寻找新的觅食区域。这种机制可以帮助解释混合物种喂养群的形成，并强调共享资源的物种之间的便利化的潜在重要性。
Frugivores often track ripe fruit abundance closely across local areas despite the ephemeral and typically patchy distributions of this resource. We use spatial auto- and cross-correlation analyses to quantify spatial patterns of fruit abundance and avian frugivory across a 4-month period within a forested 4.05-ha study grid in Puerto Rico. Analyses focused on two tanager species, Spindalis portoricensis and Nesospingus speculiferus, and their principal food plants. Three broad questions are addressed: (1) at what spatial scales is fruit abundance and frugivory patchy; (2) at what spatial scales do frugivores respond to fruit abundance; and (3) to what extent do spatial patterns of frugivory overlap between bird species? Fruit patch size, species composition, and heterogeneity was variable among months, despite fruit patch locations remaining relatively consistent between months. Positive correlations between frugivory and fruit abundance suggested tanagers successfully tracked fruit abundance. Frugivory was, however, more localized than fruit abundance. Scales of spatial overlap in frugivory and monthly variation in the foraging locations of the two tanager species suggested that interspecific facilitation may have been important in determining bird foraging locations. In particular, S. portoricensis, a specialist frugivore, may have relied on the loud calls of the gregarious generalist, N. speculiferus, to find new foraging areas. Such a mechanism could help explain the formation of mixed species feeding flocks and highlights the potential importance of facilitation between species that share resources.