Corticosterone Response as an Age-Specific Mediator of Nestling Body Mass in a Wild Passerine.

The environment can affect individual performance directly via resource availability or indirectly through resource allocation among competing fitness components, such as body growth and maintenance activities related to short-term survival. Corticosterone (CORT), the main glucocorticoid in birds, may be an important mediator of energy allocation to different organismal functions, but its effect on the plasticity of fitness-related traits has rarely been investigated at different ontogenetic stages. Here, we evaluated the role of baseline and stress-induced CORT on nestling development of wild great tits (Parus major) under different growth conditions and at different developmental stages.

Acute embryonic exposure to corticosterone alters physiology, behaviour and growth in nestlings of a wild passerine.

Maternally-derived glucocorticoids can modify the normal development of young animals. To date, little is known about maternal effects that are mediated by acute embryonic exposure to glucocorticoids. In birds, elevated maternal transmission of corticosterone (CORT) to egg albumen is mainly dependent on acute stress.

Predator encounters have spatially extensive impacts on parental behaviour in a breeding bird community.

Predation risk has negative indirect effects on prey fitness, partly mediated through changes in behaviour. Evidence that individuals gather social information from other members of the population suggests that events in a community may impact the behaviour of distant individuals. However, spatially wide-ranging impacts on individual behaviour caused by a predator encounter elsewhere in a community have not been documented before.

Development of stress response in nestling pied flycatchers.

Birds respond to unpredictable events by secreting corticosterone, which induces various responses to cope with stressful situations. However, the evidence is still elusive whether altricial nestlings perceive and respond to external stressors. We investigated the development of adrenocortical stress response to handling-related stressor in nestlings of a small passerine bird, the pied flycatcher (Ficedula hypoleuca).