Spatial, temporal and individual-based differences in nest-site visits and subsequent reproductive success in wild great tits

The behaviour of individual birds before and during the breeding period may be an important factor determining reproductive success. One commonly observed behaviour during the breeding period in many species is the visitation of multiple potential breeding sites. Much research has attempted to determine the function and consequences of this behaviour, but traditionally studies have been limited to not examining individual-level behaviour, or only considering a small number of individuals. We used automated recording of RFID-tagged birds visiting nestboxes to study a population of 80 great tits (Parus major) making >3500 daily visits across 74 breeding sites, to quantify the frequency, spatial patterning, and temporal occurrence of this behaviour from the pre-breeding period onwards. We argue that (i) the tight spatial clustering of visits, (ii) juveniles visiting more sites than adults, and (iii) males (but not females) continuing to visit other sites even as egg laying at their own nest occurs, indicate that territoriality and extra-pair mating may underpin visitation behaviour. Further, we find that spatial clustering of female visits relates to increased clutch size and fledging success, while frequently visiting a preferred nesting site increases the likelihood of obtaining a breeding site but reduces subsequent reproductive output for both sexes. Our study offers new insight into the mechanisms potentially driving breeding site visitation behaviour, and demonstrates its relationship to individual fitness. We suggest that although visitation behaviour may be related to different components of fitness, future work should use experiments to fully assess the causal factors and effects of visitation behaviour.

繁殖期前后的个体鸟类行为，或是决定其繁殖成功率的关键影响因素。诸多鸟类在繁殖期内的一类常见行为，是造访多个潜在繁殖位点。已有诸多研究试图阐明该行为的功能与影响后果，但传统研究要么未能考察个体层面的行为模式，要么仅针对少量个体展开分析。本研究通过自动记录被射频识别（RFID）标记的鸟类造访巢箱的行为，对包含80只大山雀（Parus major）的种群开展研究——该种群在74个繁殖位点累计完成超3500次单日造访，以此量化繁殖前期以来该行为的发生频率、空间格局与时间分布特征。我们提出以下三项推论：其一，造访行为存在显著的空间聚集性；其二，幼鸟造访的繁殖位点数多于成鸟；其三，雄性（而非雌性）即便在自身巢箱产卵后，仍会持续造访其他位点。上述结果表明，领域性与配对外交配或是驱动该造访行为的核心机制。进一步研究发现，雌性造访行为的空间聚集性与更大的窝卵数及更高的出飞成功率相关；而频繁造访偏好巢址的个体，虽更易获得繁殖位点，但两性的后续繁殖产出均会降低。本研究为解析繁殖位点造访行为的潜在驱动机制提供了全新视角，并证实了该行为与个体进化适合度之间的关联。我们认为，尽管造访行为可能与适合度的不同维度相关，未来仍需通过实验研究全面评估该行为的因果影响因素与效应。