Spatial-temporal variation in reproduction and site fidelity of spectacled eiders on the Yukon-Kuskowkim Delta, Alaska

Abstract

In response to recent decline, we compared migration and nesting chronology, nest success, and clutch size of spectacled eiders nesting at Kigigak Island with those nesting on Kashunuk River to better understand regulation of the spectacled eider breeding population on Y-K Delta. We also examined and compared subpopulation relationships between nest site fidelity and breeding performance. We examined the relationship between female age and distance moved between consecutive year nest sites. Clutch sizes were comparable between the two sites and declined seasonally with older females laying earlier and larger clutches. Mayfield nest success was higher due to lower predation and females moved shorter distances between nest sites at Kigigak Island. Breeding performance measures were not related to distance moved within study areas. Among study areas, successful females moved shorter distances. High adult survival, nest success, and probably different site fidelity at Kigigak Island have resulted in an increasing population, in contrast to Kashunuk River.