Wild animals are brought into captivity for many reasons—conservation, research,
agriculture and the exotic pet trade. While the physical needs of animals are met in captivity …

Permanent changes in the surrounding environment cause long-term stress in birds, which,
when lasting days or weeks, affects the activity of the immune system and increases …

Body condition is an important concept in behaviour, evolution and conservation, commonly
used as a proxy of an individual's performance, for example in the assessment of …

Blood parasites are often considered as indicators of immunity in birds, and data on parasite
prevalence and intensity of infections are essential to reveal information about the condition …

Small animals that winter at northern latitudes need to maximize energy intake and minimize
energy loss. Many passerine birds use night-time hypothermia to conserve energy. A …

The development of costly traits such as immune function and secondary sexual traits is
constrained by resource availability. The quality of developmental conditions and the …

We tested the two main evolutionary hypotheses for an association between immunity and
personality. The risk-of-parasitism hypothesis predicts that more proactive (bold, exploratory …

Nest predation is among the most important selective pressure sha** nest-site selection
and nest defense behavior in many avian species. In this study, we tested whether the …

Performance on different cognitive tasks varies between individuals within species. Recent
evidence suggests that, in some species, this variation reflects the existence of coherent …

If a single mechanism influences multiple traits, it may facilitate functional integration or
impede optimal trait expression to produce consistent individual differences and correlations …