Feather corticosterone reveals effect of moulting conditions in the autumn on subsequent reproductive output and survival in an Arctic migratory bird / N. Jane Harms, Pierre Legagneux, H. Grant Gilchrist, Joel Bety, Oliver P. Love, Mark R. Forbes, Gary R. Bortolotti, and Catherine Soos.

Includes bibliographical references.

For birds, unpredictable environments during the energetically stressful times
of moulting and breeding are expected to have negative fitness effects. Detecting
those effects however, might be difficult if individuals modulate their
physiology and/or behaviours in ways to minimize short-term fitness costs.
Corticosterone in feathers (CORTf) is thought to provide information on total
baseline and stress-induced CORT levels at moulting and is an integrated
measure of hypothalamic–pituitary–adrenal activity during the time feathers
are grown.We predicted that CORTf levels in northern common eider females
would relate to subsequent body condition, reproductive success and survival,
in a population of eiders nesting in the eastern Canadian Arctic during a capricious
period marked by annual avian cholera outbreaks. We collected CORTf
data fromfeathers grown during previousmoult in autumn and data on phenology
of subsequent reproduction and survival for 242 eider females over 5 years.
Using path analyses,we detected a direct relationship between CORTf and arrival
date and body condition the following year. CORTf also had negative
indirect relationships with both eider reproductive success and survival of
eiders during an avian cholera outbreak. This indirect effect was dramatic
with a reduction of approximately 30% in subsequent survival of eiders
during an avian cholera outbreak when mean CORTf increased by 1 standard
deviation. This study highlights the importance of events or processes occurring
during moult on subsequent expression of life-history traits and relation to individual
fitness, and shows that information from non-destructive sampling of
individuals can track carry-over effects across seasons.