Animals usually show distinct periods of diel activity and non-activity. Circulating baseline
levels of glucocorticoid hormones (corticosterone and cortisol) often peak just before or at …

The influence of variation in individual state on key reproductive decisions impacting fitness
is well appreciated in evolutionary ecology. Rowe et al.(1994) developed a condition …

Several predator–prey systems are in flux as an indirect result of climate change. In the
Arctic, earlier sea-ice loss is driving polar bears (Ursus maritimus) onto land when many …

Birds that migrate from temperate areas to the Arctic to breed lose their strongest Zeitgeber
of circadian organization when they cross the Arctic circle in spring: the 24h light-dark cycle …

African penguins (Spheniscus demersus) are an endangered species, with approximately
70,000 mature adults remaining in the wild. Population loss is linked to a combination of …

The 24 h geophysical light-dark cycle is the main organizer of daily rhythms, scheduling
physiology and behavior. This cycle attenuates greatly during the continuous light of …

Reproduction is one of the most energetically costly life history stages, which impose
constraints, even outside the breeding period. Capital breeders typically accumulate energy …

Here we describe the excretion pattern of corticosterone metabolites collected from
droppings in barnacle goslings (Branta leucopsis) raised under 24 hours of continuous …

Fecal corticosterone metabolite (FCM) concentrations, which can be determined
noninvasively, have recently been explored as a stress indicator in birds. In our study, we …

Daily rhythms for hormonal traits are likely widespread and important aspects of organismal
(eg, life history) adaptation. Yet they remain substantially understudied, especially with …