An Experimental Analysis of Mixed‐Species Flocking in Birds of Deciduous Woodland
An Experimental Analysis of Mixed‐Species Flocking in Birds of Deciduous Woodland
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DOI：
10.2307/1939176
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发表时间：
1985-08
期刊：
影响因子：
4.8
通讯作者：
T. Berner;T. Grubb
中科院分区：
文献类型：
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作者：
T. Berner;T. Grubb
关于参与混合物种觅食群体的适应性优势，已经建立了两个通用模型。一个模型强调在异种群体中获得更高的摄食效率，而另一个模型则提出了参与这种物种复合体的反捕食者优势。从这些模型中，得出了两个相互矛盾的预测，即为通常参与混合物种群体的鸟类提供过量食物资源的后果。在研究的第二个冬天，我们在俄亥俄州中部的两个林地用鸟类测试了这些预测，并为其中一个林地提供了过剩的葵花籽和牛肉油。此外，我们还研究了添加食物对鸟类种群密度、异种鸟群大小和组成的影响。卡罗莱纳山雀、白胸Nuthatches、棕色爬行动物、簇毛山雀和绒毛啄木鸟在添加食物的地区的混合物种群集都比对照组显著减少。这些结果否定了对捕食者的保护是混合物种聚集的充分原因，并支持了单独提高摄食效率或摄食效率和捕食者保护相结合导致动物在混合物种群体中觅食的观点。
Two general models have been developed concerning the adaptive advantages of par- ticipating in mixed-species foraging groups. One model emphasizes the increased feeding efficiency to be obtained in heterospecific groups, while the other model advances the antipredator advantages of participation in such species complexes. From these models, two conflicting predictions were made about the consequences of providing a superabundant food resource to birds that normally engage in mixed-species flocking. We tested these predictions over the course of two winters with birds in two central Ohio woodlots, provisioning one of the two woodlots with a superabundant supply of sunflower seeds and beef suet during the second winter of the study. In addition, we examined the effects of added food on the density of bird species, and on the size and composition of heterospecific flocks. Carolina Chickadees, White-breasted Nuthatches, Brown Creepers, Tufted Titmice, and Downy Woodpeckers all exhibited significant decreases in mixed-species flocking in the area with added food relative to the controls. These results reject protection from predators as a sufficient cause for mixed- species flocking, and support the view that either increased feeding efficiency alone or feeding efficiency and predation protection in combination cause animals to forage in mixed-species groups.