Multiple-scale temporal variation in the feeding of four species of seabird on Machias Seal Island, New Brunswick

Food is theorized to be a limiting factor in defining life-history characteristics of birds. Seabirds are useful study species when exploring questions regarding relationships with prey, as they breed in dense colonies with restricted foraging ranges and many carry prey to chicks in their bill, allowing for prey identification. I used ten years of data from four seabird species: Atlantic Puffin (Fratercula arctica), Razorbill (Alca torda), Common Tern (Sterna hirundo), and Arctic Tern (S. paradisaea), to examine relationships of seabirds with their prey during chick-rearing, investigating boundaries between diets within and among breeding seasons. The proportion of herring fed to chicks declined in all species from 1995--2004. However, I saw no consistent trend in amounts of dietary overlap over years. Seabirds locate foraging flocks visually, but fog limits visibility. I predicted fog would reduce feeding rates of seabirds, and would result in adults feeding fewer schooling fish while feeding their chicks a greater variety of prey types, but the data did not support my hypotheses.