Spatial and temporal variation in tufted puffin Fratercula cirrhata nestling diet quality and growth rates

Seabirds have long been promoted as bio-indicators, because parameters such as reproductive success, nestling growth rates, and diet composition respond markedly to changes in food supply. Although such responses are often associated with broad-scale oceanographic phenomena, they are also influenced by processes that occur on much smaller spatial scales. We quantified Tufted Puffin Fratercula cirrhatanestling growth rates, apparent fledging success, and diets at several colonies in Chiniak Bay, Kodiak Island, Alaska from 2003-2005. We also measured the lipid content of forage fish fed to nestlings, because diet selection is expected to be influenced by prey quality. Although apparent fledging success was generally high, complete reproductive failure occurred at one small colony in all years, possibly due to mammalian predators. In 2003, we found a striking difference in diet composition between colonies, with nestlings on Chiniak Island in the outer bay consuming primarily Pacific sand lance Ammodytes hexapterus (50%) and capelin Mallotus villosus (45%) and nestlings at Cliff Island in the inner bay (22 km away) having a diet dominated (76%) by lower quality Pacific sandfish Trichodon trichodon. Our results indicate that Tufted Puffin diets can vary on a relatively small spatial scale and that puffins may settle for lower quality prey when it is readily available in close proximity to the breeding colony.