Whilst the immune system often varies seasonally and exhibits differences between males
and females, the general patterns in seasonality and sex differences across taxa have …

Stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of
glucocorticoids can have detrimental effects on the brain. Dehydroepiandrosterone (DHEA) …

The 13C-labelled Na-bicarbonate technique uses stable isotopes to measure energy
expenditure in birds. After administration, the isotopes reach equilibrium within the body's …

Exogenous nutrients do not diffuse throughout the body like a drop of dye in a beaker of
water. Rather, they are allocated among tissues according to physiological rules determined …

Secondary sexual traits in males are thought to convey information about the quality of the
male to rivals and potential mates. Semi-static signals such as sexually selected plumage …

Blood glucose plays an essential role in the body's energy metabolism; however, sources of
variation in baseline and stress-induced changes in glucose concentration remain poorly …

Both mass (as a measure of body reserves) during breeding and adult survival should reflect
variation in food availability. Those species that are adapted to less seasonally variable …

Organisms that breed multiple times must trade off resources between current and future
reproduction. In many species, sexual selection can lead to reduced levels of immune …

Pelagic fish are an important component of Antarctic food webs but few quantitative data
exist on energy transfer from fish to seabirds for the Seasonal Pack-ice Zone. We studied a …

The Eastern Black Rail (Laterallus jamaicensis jamaicensis) is a subspecies that winters
mainly along the Gulf and Atlantic Coasts of the United States. Declines in Eastern Black …