Data on nest choices by long-tailed tit helpers

Cooperative breeding sometimes occurs when adult breeders form groups following natal dispersal and mating. In such cases, individuals typically face a choice of potential social partner with whom to cooperate. Selection of appropriate social partners is crucial to maximising the fitness payoffs from cooperation, but our understanding of the criteria guiding social partner choice is limited. Here, we analyse helping decisions by long-tailed tits (Aegithalos caudatus), which may redirect their care to assist breeders in raising offspring following the failure of their own breeding attempts. In this species, helpers show a preference for helping relatives at nearby nests, but it is unclear whether other criteria that may affect helper fitness are also important in helping decisions. Contrary to expectations, when controlling for kinship, we found that helping decisions were not sensitive to the size or age of broods available to be helped. Individuals were, however, more likely to help br...合作繁殖（cooperative breeding）有时会在成年繁殖个体完成出生扩散（natal dispersal）并完成交配后形成群体时发生。在此类情境中，个体通常需要在潜在的社会伙伴中选择合作对象。选择合适的社会伙伴对最大化合作带来的适合度收益至关重要，但目前我们对指导社会伴侣选择的评判标准的认知仍较为有限。本研究以长尾山雀（Aegithalos caudatus）为对象，分析其帮助繁殖的决策行为：该物种的个体在自身繁殖尝试失败后，可能会转向协助其他繁殖个体抚育后代。此前研究发现，该物种的帮助者更倾向于帮助邻近巢穴的亲属，但尚不明确其他可能影响帮助者适合度的评判标准是否同样会对帮助决策产生影响。与预期相悖的是，在控制亲缘关系（kinship）变量后，我们发现帮助决策并不会受可供协助的雏鸟窝的规模或窝龄影响。不过，个体更倾向于帮助……