Data from: Allopreening in birds is associated with parental cooperation and stable pair bonds across years

Individuals of many species form bonds with their breeding partners, yet the mechanisms maintaining these bonds are poorly understood. In birds, allopreening is a conspicuous feature of interactions between breeding partners and has been hypothesised to play a role in strengthening and maintaining pair bonds within and across breeding attempts. Many avian species, however, do not allopreen and the relationship between allopreening and pair-bonding across species remains unexplored. In a comparative analysis of allopreening and pair-bond behaviour, we found that allopreening between breeding partners was more common among species where parents cooperate to rear offspring. The occurrence of allopreening was also associated with an increased likelihood that partners would remain together over successive breeding seasons. However, there was no strong evidence for an association between allopreening and sexual fidelity within seasons or time spent together outside the breeding season. Allopreening between partners was also no more common in colonial or cooperatively-breeding species than in solitary species. Analyses of evolutionary transitions indicated that allopreening evolved from an ancestral state of either high parental cooperation or high partner retention, and we discuss possible explanations for this. Overall, our results are consistent with an important role for allopreening in the maintenance of avian pair bonds.

诸多物种的个体都会与其繁殖配偶形成社会联结，但维持这类联结的具体机制仍未得到充分阐释。在鸟类中，互理羽毛（allopreening）是繁殖配偶间互动的显著特征，此前有假说认为其可在单次乃至多次繁殖过程中，强化并维持配偶间的联结。然而，诸多鸟类物种并不会发生互理羽毛行为，跨物种层面上互理羽毛与配偶联结之间的关联仍未得到探究。在一项针对互理羽毛与配偶联结行为的比较分析中，我们发现，繁殖配偶间的互理羽毛行为在双亲共同抚育后代的物种中更为常见。互理羽毛行为的出现，还与配偶在多个繁殖季间持续结伴的概率提升存在关联。不过，并未发现有力证据表明，互理羽毛行为与繁殖季内的性忠诚性或繁殖季外配偶共处时长存在关联。配偶间的互理羽毛行为，在集群性或合作繁育物种中的出现频率，也并未高于独居物种。演化过渡分析显示，互理羽毛行为起源于双亲合作程度高或配偶留存率高的祖先类群，本文还就这一现象的潜在成因展开了讨论。总体而言，我们的研究结果支持互理羽毛行为在维持鸟类配偶联结中发挥着重要作用这一观点。