Helper effects in the azure-winged magpie Cyanopica cyana in relation to highly-clumped nesting pattern and high frequency of conspecific nest-raiding
Helper effects in the azure-winged magpie Cyanopica cyana in relation to highly-clumped nesting pattern and high frequency of conspecific nest-raiding
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DOI：
10.1111/jav.00783
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发表时间：
2016-07-01
影响因子：
1.7
通讯作者：
Du, Bo
中科院分区：
文献类型：
--
作者：
Ren, Qing-Miao;Luo, Shuang;Du, Bo
在鸟类合作育种系统中，社会对从帮手的存在中获得的许多好处已经被发现。然而，到目前为止，决定帮助者提供的援助类型和社会对的反应的因素还没有得到很好的说明。研究了在青藏高原繁殖的青翅鹊Cyanapica cyana的辅助个体对合作群体的贡献以及优势个体对合作群体的相关反应。我们使用capture-mark-recapture方法来识别助手。结果表明，助育者多为优势对的一岁子。它们主要通过三种方式对合作群体做出贡献，即求偶-喂养孵化中的雌性，提供育雏和保卫巢穴。对于优势对的反应，我们意外地发现窝卵大小不受巢穴中帮手存在的影响。然而，合作组有较高的育雏喂养率比双亲巢，他们的喂养模式也不同于后者。因此，雏鸟在合作组有更大的雏鸟的身体质量比双亲巢。通过研究巢失败的原因，我们发现，同种巢袭击造成更多的巢失败比任何其他自然捕食者。由于协助者在防御捕食者和同种巢袭者方面的贡献，合作组比双亲巢有更高的存活率。因此，我们的研究结果表明，在一个高度丛生的筑巢模式，有关巢捕食的风险，而不是影响食物供应的因素，发挥了重要作用，在确定辅助效应和反应的辅助优势对。
In avian cooperative breeding systems, many benefits obtained by social pairs from the presence of helpers have been uncovered. However, until now, the factors that determine the type of assistance helpers provide and the responses of social pairs have not been well illustrated. We examined the contribution of helpers to cooperative groups and the relevant responses of dominant pairs in the azure-winged magpie Cyanapica cyana which breeds on the Tibetan Plateau. We used the capture-mark-recapture method to identify helpers. Results showed that helpers were mostly the yearling sons of dominant pairs. They mainly contributed to the cooperative group in three ways, courtship-feeding the incubation female, provisioning the brood, and defending the nest. For responses of dominant pairs, we unexpectedly found that clutch size was not influenced by the presence of helpers at the nest. However, cooperative groups had higher brood feeding rates than biparental nests and their feeding pattern also differed to that of the latter. Consequently, nestlings in cooperative groups had larger fledging body mass than that in biparental nests. By examining reasons for nest failure, we revealed that conspecific nest-raiding contributed to more nest failure than any other natural predators. Because of the contribution of helpers in defending against both predators and conspecific nest-raiders, cooperative groups had higher survival rate than biparental nests. Thus, our findings suggest that in a highly-clumped nesting pattern, factors concerning the risk of nest predation, rather than that influencing food supply, play an important role in determining helper effects and responses of aided dominant pairs.