Increased energy expenditure by a seabird in response to higher food abundance

• Published in: Marine ecology. Progress series (Halstenbek) 2006-01, Vol.306, p.283-293
• Main Authors: Jodice, Patrick G. R., Roby, Daniel D., Suryan, Robert M., Irons, David B., Turco, Kathy R., Brown, Evelyn D., Thedinga, John F., Visser, G. Henk
• Format: Article
• Language: English
• Subjects: Ammodytes hexapterus; Animal and plant ecology; Animal, plant and microbial ecology; Aves; Biological and medical sciences; Brackish; Chicks; Clupea; Clupea pallasii; Density; Diet; Flux density; Food availability; Forage; Foraging; Fundamental and applied biological sciences. Psychology; Herring; Marine; Rissa tridactyla; Sea birds; Sea water ecosystems; Surface areas; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps306283

Variability in forage fish abundance strongly affects seabird behavior and reproductive success, although details of this relationship are unclear. During 1997 and 1998, we measured (1) daily energy expenditure (DEE) of 80 parent black-legged kittiwakesRissa tridactylaat 2 colonies in Prince William Sound, Alaska (North Icy Bay and Shoup Bay), (2) abundance of surface-schooling forage fishes within the foraging range of each colony, and (3) diet composition, energy delivery rates to nestlings, and reproductive success of kittiwakes at these same colonies. Female DEE was highest at North Icy Bay in 1998, while male DEE did not differ by colony year. Abundances of Pacific herringClupea pallasiand sand lanceAmmodytes hexapteruswere highest near North Icy Bay in 1998 and nearly equal in density, although Age 1+ herring comprised the majority of the diet there. Energy delivery rates to nestlings, nestling growth rates, and productivity were also highest at North Icy Bay in 1998. We suggest that female kittiwakes responded to the increased abundance of Age 1+ herring near North Icy Bay in 1998 by increasing their DEE, which in turn positively affected reproductive success. Given that adult kittiwakes have been shown to suffer decreased survival as a response to increased energy expenditure during brood rearing, the positive correlation we observed between increased abundance of a high quality food source, parental effort, and productivity is consistent with maximizing lifetime reproductive success. The lack of a response in male DEE suggests that brood-rearing roles in kittiwakes differ between genders.