Planktivorous Auklets (Aethia pusilla and A. cristatella) nesting on St. Lawrence Island, Alaska as indicators of marine conditions in the northern Bering Sea

• Main Author: Gall, Adrian
• Other Authors: Roby, Daniel D., Miller, Charles, Anthony, Robert, Fisheries and Wildlife, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Least auklet > Health > Alaska > Saint Lawrence Island; Crested auklet > Alaska > Saint Lawrence Island > Reproduction; Least auklet > Food > Alaska > Saint Lawrence Island; Least auklet > Alaska > Saint Lawrence Island > Nutrition; Crested auklet > Food > Alaska > Saint Lawrence Island; Crested auklet > Health > Alaska > Saint Lawrence Island; Crested auklet > Alaska > Saint Lawrence Island > Nutrition; Least auklet > Alaska > Saint Lawrence Island > Reproduction; Bering Sea; Savoonga; St Lawrence Island; Alaska; Copepods
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/q237ht957

Monitoring reproductive success, prey species composition, and colony size of marine birds has been proposed as a method of assessing changes in marine systems that are otherwise difficult to sample (Cairns 1987). I measured inter-annual and intra-seasonal variability in reproductive parameters, taxonomic composition of the diet, and adult body condition of Crested Auklets (Aethia cristatella) and Least Auklets (A. pusilla) at 2 colonies near the village of Savoonga, St. Lawrence Island, Alaska during the 2000-2002 breeding seasons to evaluate how reproductive success of planktivorous seabirds is related to diet. I also assessed the utility of two methods of population monitoring (surface counts and mark-resighting) for detecting annual changes in breeding populations of Crested and Least auklets during the 2001 and 2002 breeding seasons on the Kitnik colony. Average reproductive success was generally high (>60% of nests) for both auklet species during the 3 years of the study, but differed among years. Median hatching dates for both species were 2 weeks earlier in the year of highest reproductive success (2002), compared to the previous 2 years. In all 3 years, the diet of Crested Auklets was predominantly euphausiids, while the diet of Least Auklets consisted primarily of calanoid copepods, but species composition of the diet differed among years for both species. Crested and Least auklets consumed more of the large, lipid-rich copepod Neocalanus cristatus in 2002 than in the other 2 years of the study. The year of lowest reproductive success (2001) was associated with low prevalence of euphausiids in Crested Auklet diets late in the chick-rearing period and high prevalence of the small, low-lipid copepod Calanus marshallae in Least Auklet diets. I observed an increase in total body mass of Crested Auklets during the 2002 breeding season, whereas total body mass declined through the breeding season in the other 2 years. Seasonal changes in adult body mass of Crested Auklets may, therefore, be a useful ...