Consistent inter-individual differences in behavioural phenotypes may entail differences in energy efficiency and expenditure, with different fitness payoffs. In colonial-breeding species, inter-individual differences in foraging behaviour may evolve to reduce resource use overlap among conspecifics exploiting shared foraging areas. Furthermore, individual differences in foraging behaviour may covary with individual characteristics, such as sex or physiological conditions. We investigated individual differences in foraging tactics of a colonial raptor, the lesser kestrel (Falco naumanni). We tracked foraging trips of breeding individuals using miniaturized biologgers. We classified behaviours from GPS data and identified tactics at the foraging trip level by cluster analysis. We then estimated energy expenditure associated to each tactic from tri-axial accelerometer data. We obtained 489 foraging trips by 36 individuals. Two clusters of trips were identified, one (SF) characterized by more static foraging behaviour and the other (DF) by more dynamic foraging behaviour, with a higher proportion of flying activity and a higher energy expenditure compared to SF. Lesser kestrels showed consistent inter-individual differences in foraging tactics across weather condition gradients, favouring DF trips as solar radiation and crosswind intensity increased. DF trips were more frequent during the nestling-rearing than during the egg incubation stage. Nestlings whose tracked parent was more prone to perform DF trips experienced higher daily mass increase, irrespective of nestling feeding rates. Our study provided evidence that breeding lesser kestrels flexibly adopted different foraging tactics according to contingent weather landscapes, with birds showing consistent inter-individual differences in the tendency to adopt a given tactic. The positive correlation between the tendency to perform more energy-demanding DF trips and nestling growth suggests that individual differences in foraging behaviour may play a role in maintaining key life-history trade-offs between reproduction and self-maintenance.

中文翻译：

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殖民地猛禽觅食策略的个体差异：一致性、天气影响和健康相关。

行为表型中一致的个体间差异可能导致能量效率和支出的差异，以及不同的健身回报。在群居繁殖的物种中，觅食行为的个体间差异可能会演变，以减少利用共享觅食区域的同种之间的资源使用重叠。此外，觅食行为的个体差异可能与个体特征（如性别或生理条件）共同变化。我们调查了殖民地猛禽小红隼 (Falco naumanni) 觅食策略的个体差异。我们使用小型生物记录仪跟踪繁殖个体的觅食之旅。我们从 GPS 数据中对行为进行分类，并通过聚类分析确定觅食行程级别的策略。然后，我们根据三轴加速度计数据估计与每种策略相关的能量消耗。我们获得了 36 个人的 489 次觅食行程。确定了两个旅行集群，一个（SF）以更静态的觅食行为为特征，另一个（DF）以更动态的觅食行为为特征，与SF相比，飞行活动比例更高，能量消耗更高。较小的红隼在不同天气条件梯度的觅食策略上表现出一致的个体间差异，随着太阳辐射和侧风强度的增加，有利于 DF 旅行。在雏鸟饲养期间，DF 旅行比在蛋孵化阶段更频繁。无论雏鸟喂养率如何，被追踪的父母更倾向于进行 DF 行程的雏鸟每天的体重增加更高。我们的研究提供的证据表明，繁殖较小的红隼根据可能的天气景观灵活地采用不同的觅食策略，鸟类在采用给定策略的倾向上表现出一致的个体间差异。进行更多能量需求的DF旅行的趋势与雏鸟生长之间的正相关表明，觅食行为的个体差异可能在维持繁殖和自我维持之间的关键生活史权衡中发挥作用。