Reproductive success usually declines in the course of the season, which may be a direct
effect of breeding time, an effect of quality (individuals with high phenotypic or environmental …

Our goal in this review is to discuss how measures beyond simple quantification of total
glucocorticoid levels are needed in comparative studies of stress. We need to measure …

1. Researchers involved in ecology and toxicology, as well as many other aspects of avian
biology, use phytohaemagglutinin (PHA) skin testing as a means of evaluating the immune …

The annual seasonal cycle accounts for much of the total temporal variability of mid-and
high-latitude marine ecosystems. Although the general pattern of the seasons repeats each …

The T-cell-mediated immune response (CMI) of birds, measured with the
phytohaemagglutinin skin test, is in most cases positively correlated with their body mass …

Predation is a central organizing process affecting populations and communities.
Traditionally, ecologists have focused on the direct effects of predation—the killing of prey …

Methods for studying the avian immune system have matured during the past two decades,
with laboratory studies predominating in earlier years and field studies being conducted only …

The number of different types of circulating leucocytes may provide information about the
health state of birds in the wild. We counted the number and proportions of circulating …

The phenology of spring migration depends on the severity of the preceding winter and
approaching spring. This severity can be quantified using the North Atlantic Oscillation …

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 …