Data for: Maternal glucocorticoid levels during incubation predict breeding success, but not reproductive investment, in a free-ranging bird

The hormone corticosterone (CORT) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. The “CORT-fitness hypothesis” proposes that high levels of CORT arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). In contrast, the “CORT-adaptation hypothesis” suggests that, during energetically demanding periods, CORT will mediate physiological or behavioural changes that result in increased reproductive investment and success (a positive relationship). During two breeding seasons, we experimentally manipulated circulating CORT levels in female tree swallows (Tachycineta bicolor) prior to egg laying, and measured subsequent reproductive effort, breeding success, and maternal survival. When females were recaptured during egg incubation and again during the nestling stage, the CORT levels were similar among individuals in each treatment group, and maternal treatment had no effect on ind...

激素皮质酮（corticosterone, CORT）被认为与生存适合度相关，但二者关联的方向性尚不明确。“皮质酮-适合度假说”（CORT-fitness hypothesis）提出，高水平的皮质酮源于挑战性环境条件，进而导致繁殖成功率降低（即二者呈负相关关系）。与之相对，“皮质酮适应假说”（CORT-adaptation hypothesis）则认为，在能量需求较高的时期，皮质酮会介导生理或行为层面的变化，从而提升繁殖投入与繁殖成功率（即二者呈正相关关系）。在两个繁殖季中，我们于产卵前对雌性树燕（Tachycineta bicolor）的循环皮质酮水平进行了实验操控，并测定了后续的繁殖投入、繁殖成功率以及母体存活率。当研究人员在卵孵化阶段以及育雏阶段再次捕获雌性个体时，各处理组个体的皮质酮水平并无显著差异，且母体的处理对……