Survival and reproductive success of Crested Auklets Aethia cristatella in the presence of introduced Norway rats Rattus norvegicus

Introduced predators, including Norway rats Rattus norvegicus, can have devastating effects on island avifauna. Nevertheless, at Kiska Island in the Aleutian Islands, one of the largest auklet colonies in Alaska, Least Auklets Aethia pusilla and Crested Auklets A. cristatella appear to be persisting in the presence of introduced Norway rats. We gathered information on annual reproductive success and adult survival of Crested Auklets at Kiska during 2001-2010 and compared these demographic rates with those of Crested Auklets at rat-free Buldir and Kasatochi Islands in the Aleutian Islands. Although those on Kiska frequently had the lowest reproductive success among the islands in a given year, we did not detect a statistically significant mean difference with our relative small samples from Kiska. Restricting the analysis to years when rats were abundant at Kiska (2001-2002), Crested Auklets on Kiska had lower reproductive success than those on rat-free islands. Adult survival at Kiska declined through our study period and was estimated at <80% near the end of our study. The data we gathered provides the basis for a more detailed study in the future to more clearly determine the impacts of introduced Norway rats on Crested Auklet populations at Kiska.