Alaska Science Center
Are corticosterone levels a good indicator of food availability and reproductive performance in a black-legged kittiwake colony?
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Product Type: Journal Article
Authors: Lanctot, R. B., S. A. Hatch, V. A. Gill, and M. Eens
We evaluated the use of corticosterone to gauge forage availability and predict reproductive performance in black-legged kittiwakes (Rissa tridactyla) breeding in Alaska during 1999 and 2000. We modelled the relationship between baseline levels of corticosterone and a suite of individual and temporal characteristics of the sampled birds. We also provided supplemental food to a sample of pairs and compared their corticosterone levels with pairs that were not fed. Corticosterone levels were a good predictor of forage availability in some situations, although inconsistencies between corticosterone levels and reproductive performance of fed and unfed kittiwakes suggested this was not always the case. Higher corticosterone levels were found in birds that lacked breeding experience at the colony. In general, all parameters investigated explained only a small proportion of the variance in corticosterone levels. We also investigated whether corticosterone, supplemental feeding, year of the study, breeding experience, body weight and the sex of a bird were able to predict laying, hatching, and fledging success in kittiwakes. Here, breeding experience, year of the study, and body weight were the best predictors of a birdís performance. Corticosterone level and supplemental feeding were good predictors of kittiwake reproductive performance in some cases. For example, corticosterone levels of birds sampled during the arrival stage reliably predicted laying success, but were less reliable at predicting hatching and fledging success. Similarly, supplemental feeding had strong affects on kittiwake productivity when natural forage was poor, but had little affect when natural forage was plentiful.