Adverse foraging conditions may impact body mass and survival of a high Arctic seabird

Tradeoffs between current reproduction andfuture survival are widely recognized, but may only occurwhen food is limited: when foraging conditions arefavorable, parents may be able to reproduce withoutcompromising their own survival. We investigated thesetradeoffs in the little auk (Alle alle), a small seabird with asingle-egg clutch. During 2005–2007, we examined therelationship between body mass and survival of birdsbreeding under contrasting foraging conditions at twoArctic colonies. We used corticosterone levels of breedingadults as a physiological indicator of the foraging conditionsthey encountered during each reproductive season.We found that when foraging conditions were relativelypoor (as reflected in elevated levels of corticosterone),parents ended the reproductive season with low body massand suffered increased post-breeding mortality. A positiverelationship between body mass and post-breeding survivalwas found in one study year; light birds incurred highersurvival costs than heavy birds. The results of this studysuggest that reproducing under poor foraging conditionsmay affect the post-breeding survival of long-lived littleauks. They also have important demographic implicationsbecause even a small change in adult survival may have alarge effect on populations of long-lived species.