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Large numbers of Long-tailed Ducks (Clangula hyemalis) (10 000 – 30 000) undergo a postnuptial wing molt along barrier islands of the Beaufort Sea, Alaska. To investigate the potential effects of underwater seismic activities on this species, we monitored the number and diving behavior of molting Long-tailed Ducks before, during, and after seismic activities in a seismic area and two control areas nearby between July and September 2001. Aerial surveys documented a decline in duck numbers in both seismic and control areas during the period of seismic activity. We used automated data-collection computers to monitor the presence and diving behavior of radio-equipped Long-tailed Ducks residing within 2.5 km of a series of computer setups located along the barrier islands and on the mainland. A statistical analysis based on a modified before–after control–impact approach found no difference in indices of site fidelity or diving intensity between the seismic area and two control areas. Thus, we found no effect of seismic activity on movements and diving behavior of molting Long-tailed Ducks. These results should be evaluated carefully, however, as logistical and ecological factors limited our ability to detect more subtle disturbance effects. We recommend additional studies on other bird species to fully understand the effects of underwater seismic testing. [ABSTRACT FROM AUTHOR]

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 modeled 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 that of 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 that this was not always the case. In general, higher corticosterone levels were found in birds that lacked breeding experience and in birds sampled shortly after arriving from their wintering grounds. All parameters investigated, however, 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 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 bird’s 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. Counts of active nests with eggs or chicks may be more reliable estimates of the actual productivity of the colony. Supplemental feeding had strong effects on kittiwake productivity when natural forage was poor, but had little effect when natural forage was plentiful. [Copyright &y& Elsevier]

We used a supplemental-feeding experiment, the doubly labeled water technique, and a model-selection approach based upon the Akaike Information Criterion to examine effects of food availability on energy expenditure rates of Black-legged Kittiwakes, Rissa tridactyla, raising young in Middleton Island, Alaska. Energy expenditure rates of females were more responsive to fluctuations in food availability than those of males. Our objectives were to determine if the energy expenditure rates of parent kittiwakes provided with supplemental food, differed from those of control parents, and to determine the strength of the relationship between parental energy expenditure rates and a suite of extrinsic and intrinsic covariates and factors. Fed males likely expended more energy while off the nest than fed females, possibly because of nest defense. Energy expenditure rates of fed kittiwakes were similar to values reported for kittiwakes that were either not raising young or not foraging. Fed kittiwakes increased their reproductive output while simultaneously decreasing parental effort and increasing body condition. Parent kittiwakes, therefore, adjusted parental effort in response to variation in breeding conditions due to changes in food availability. Adjustments in reproductive effort in response to variable foraging conditions may have significant effects on the survival and productivity of individuals, and thus provide substantial fitness benefits for long-lived seabirds such as Black-legged Kittiwakes. Differences in survival rates between the sexes may occur if each sex experiences a different survival curve with respect to field metabolic rate or parental effort.