Territory quality affects the relative importance of habitat heterogeneity and interference competition in a long-lived territorial songbird
Territory quality affects the relative importance of habitat heterogeneity and interference competition in a long-lived territorial songbird
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DOI：
10.1111/j.1600-048x.2013.00182.x
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发表时间：
2014-01-01
影响因子：
1.7
通讯作者：
Krueger, Oliver
中科院分区：
文献类型：
--
作者：
Gruenkorn, Thomas;Potiek, Astrid;Krueger, Oliver
密度依赖性繁殖通常由栖息地异质性（HHH）或个体调节（IAH）假说来解释。在HHH下，高质量的领土被假定为首先被占领。在较高密度下，由于高质量领土的可用性较低，低质量领土的占用增加，这降低了平均繁殖成功率。或者，IAH假设，在更高的密度增加竞争减少了所有领域的繁殖成功。对于猛禽，HHH在领土物种中起重要作用，IAH在社会繁殖物种中起重要作用。为了检验这一假设的普遍性，我们研究了乌鸦Corvus corax，长寿雀形目鸟类，使用来自大量领土的长期人口数据的密度依赖背后的机制。人口密度降低了繁殖，这是由高密度下低质量领土的使用增加解释的，支持HHH。密度降低繁殖在低质量的领土，但不是在高和中等质量的领土。我们还比较了不同模型描述育雏大小的解释力，代表IAH，HHH，或两者的组合。最好的模型代表了这两个假设的组合，其中密度的影响取决于领土质量。我们的结论，IAH和HHH的支持可以解释乌鸦的生物学，领土的成年人不仅经历干扰竞争与其他领土的成年人，但也与社会群体的青少年和漂浮物。我们的结论是，IAH和HHH的相对重要性可能取决于领土质量和社会结构的变化。
Density-dependent reproduction is commonly explained by either the habitat heterogeneity (HHH) or individual adjustment (IAH) hypothesis. Under the HHH, high quality territories are assumed to be occupied first. At higher density, occupation of low-quality territories increases due to lower availability of high-quality territories, which reduces mean reproductive success. Alternatively, the IAH assumes that increased competition at higher densities reduces reproductive success in all territories. For birds of prey, HHH plays an important role in territorial species, and IAH in socially breeding species. To test the generality of this hypothesis, we studied the mechanism behind density dependence in raven Corvus corax, a long-lived passerine bird, using long-term population data from a large number of territories. Population density decreased reproduction, which was explained by increased usage of low quality territories at higher density, supporting the HHH. Density reduced reproduction in low quality territories, but not in high and intermediate quality territories. We additionally compared the explanatory power of different models describing brood size, representing IAH, HHH, or a combination of both. The best model represented a combination of both hypotheses, in which the effect of density depended on territory quality. Our conclusion that both IAH and HHH are supported can be explained by the biology of ravens, where territorial adults not only experience interference competition with other territorial adults, but also with social groups of juveniles and floaters. We conclude that the relative importance of IAH and HHH may depend on variation in territory quality and social structure.