Data from: Nest size is predicted by female identity and the local environment in the blue tit, but is not related to genetic or foster mother's nest size

The potential for animals to respond to changing climates has sparked interest in intraspecific variation in avian nest structure since this may influence nest microclimate and protect eggs and offspring from inclement weather. However, there have been relatively few large-scale attempts to examine variation in nests or the determinates of individual variation in nest structure within populations. Using a set of mostly pre-registered analyses, we studied potential predictors of variation in the size of a large sample (803) of blue tit (Cyanistes caeruleus) nests across three breeding seasons at Wytham Woods, UK. Whilst our pre-registered analyses found that individual females built very similar nests across years, there was no evidence in follow-up (post hoc) analyses that their nest size correlated to that of their genetic mother or, in a cross-fostering experiment, to the nest where they were reared. In further pre-registered analyses, spatial environmental variability explained nest size variability at relatively broad spatial scales, and especially strongly at the scale of individual nestboxes. Our study indicates that nest structure is a characteristic of individuals, but is not strongly heritable, indicating that it will not respond rapidly to selection. Explaining the within-individual and within-location repeatability we observed requires further study.

动物应对气候变化的潜力，引发了学界对鸟类巢窝结构种内变异的研究兴趣，因为巢窝结构可影响巢内微气候，并保护卵与幼雏免受恶劣天气侵扰。然而，目前针对种群内巢窝变异，或巢窝结构个体变异的决定因素开展的大规模研究仍相对匮乏。本研究依托一组大部分已预先注册的分析方案，针对英国怀瑟姆森林（Wytham Woods）三个繁殖季内采集的803个大山雀（Cyanistes caeruleus）巢窝样本的大小变异，探究了其潜在预测因子。尽管预先注册的分析显示，雌性个体在不同繁殖季所筑巢窝的大小极为相似，但后续（事后）分析并未发现其巢窝大小与亲生母亲的巢窝大小存在关联，也未在交叉抚育实验中发现与抚育其成长的巢窝大小存在相关性。在进一步的预先注册分析中，空间环境变异可在相对较广的空间尺度上解释巢窝大小的变异，其中在单个巢箱尺度上的解释力尤为显著。本研究表明，巢窝结构属于个体特征，但并不具有强遗传性，这意味着巢窝结构不会对选择压力做出快速响应。要解释我们观测到的个体内与位点内重复性，仍需开展后续研究。