The effects of individual characteristics and ocean conditions on the reproductive phenology and demography of pigeon…

The Pigeon Guillemot (Cepphus columba), one of the only alcids that nests in the Salish Sea, has been identified as an indicator species by the Puget Sound Environmental Monitoring Program. Indicator status is based on Salish Sea abundance and trend, and abundance estimates suggest that the population remains stable. However, little is known about demographic rates, limiting our ability to understand how populations may respond to a changing Salish Sea ecosystem. Based on a 15-year study monitoring color-banded individuals at approximately 40 nest boxes at Protection Island National Wildlife Refuge, we estimated demographic rates and examined how life history traits and ocean conditions influence these rates. Based on repeated observations at nest boxes throughout the summer breeding season, we describe the nesting ecology, including phenology, site fidelity, incubation period, clutch size, and chick growth rate. We used Bayesian state-space mark-recapture and nest survival models to examine both the effects of individual characteristics, such as adult and chick weight, and the effects of local and large-scale ocean conditions on survival and reproductive success. Examining the effects of individual characteristics and environmental variables on a colony that is exposed to little human disturbance will lend greater insight into the physical and ecological processes that drive population trends, which will in turn give us greater insight into what this indicator species is telling us about the Salish Sea ecosystem. We hope to expand this work going forward to further our knowledge of the demography of this population in the context of foraging conditions. The results of our work will also help contextualize the findings of the Salish Sea Guillemot Network, highlighting the value of the data and insights gained from this growing community science program in Puget Sound.