Data from:Physiological effects of increased foraging effort in a small passerine

Foraging to obtain food, either for self-maintenance or at presumably elevated rates to provision offspring, is thought to be an energetically demanding activity but one that is essential for fitness (higher reproductive success and survival). Nevertheless, the physiological mechanisms that allow some individuals to support higher foraging performance, and the mechanisms underlying costs of high workload, remain poorly understood. We experimentally manipulated foraging behaviour in zebra finches (Taeniopygia guttata) using the technique described by Koetsier and Verhulst (2011). Birds in the “high foraging effort” (HF) group had to obtain food either while flying/hovering or by making repeated hops or jumps from the ground up to the feeder, behaviour typical of the extremely energetically-expensive foraging mode observed in many free-living small passerines. HF birds made significantly more trips to the feeder per 10min whereas control birds spent more time (perched) at the feeder. Despite this marked change in foraging behaviour we documented few short- or long-term effects of “training” (3 days and 90 days of “training” respectively) and some of these effects were sex-specific. There were no effects of treatment on BMR, hematocrit, hemoglobin, or plasma glycerol, triglyceride, glucose levels, and masses of kidney, crop, large intestine, small intestine, gizzard and liver. HF females had higher masses of flight muscle, leg muscle, heart and lung compared to controls. In contrast, HF males had lower heart mass than controls and there were no differences for other organs. When both sexes were pooled, there were no effects of treatment on body composition. Finally, birds in the HF treatment had higher levels of reactive oxygen metabolites (dROMs) and, consequently, although treatment did not affect total antioxidant capacity (OXY), birds in the HF treatment had higher oxidative stress.

为获取食物而进行的觅食行为，无论是用于自身能量维持，还是以推测中更高的速率为后代递送食物，均被认为是一项能量消耗极高的活动，但同时也是影响适合度（即更高的繁殖成功率与存活率）的关键行为。
尽管如此，部分个体能够维持更高觅食绩效的生理机制，以及高工作负荷所带来代价的内在机制，目前仍未得到充分阐释。
本研究采用Koetsier与Verhulst（2011）所描述的实验方法，对斑胸草雀（Taeniopygia guttata）的觅食行为进行了操控。被归入“高觅食努力组（high foraging effort, HF）”的个体，需通过飞行/悬停，或反复从地面跳跃至喂食器处的方式获取食物——这种行为模式与许多自由生活的小型雀形目鸟类所采用的极耗能觅食方式一致。
HF组的斑胸草雀每10分钟前往喂食器的频次显著更高，而对照组个体则在喂食器处栖息停留的时间更长。
尽管觅食行为发生了显著改变，但本研究仅观察到“训练”（分别为3天与90天的训练周期）带来的少量短期与长期效应，且部分效应存在性别特异性。
实验处理对基础代谢率（Basal Metabolic Rate, BMR）、红细胞比容、血红蛋白，以及血浆甘油、甘油三酯、葡萄糖水平，还有肾脏、嗉囊、大肠、小肠、肌胃与肝脏的重量均无显著影响。
与对照组相比，HF组的雌性个体的飞翔肌（flight muscle）、腿部肌肉、心脏与肺脏重量更高；与之相反，HF组的雄性个体的心脏重量低于对照组，其余器官重量则无组间差异。
当合并雌雄个体的数据时，实验处理对身体组成无显著影响。
最后，HF组个体的活性氧代谢物（reactive oxygen metabolites, dROMs）水平更高；因此，尽管实验处理对总抗氧化能力（total antioxidant capacity, OXY）无显著影响，但HF组个体的氧化应激水平更高。