Are the Salish Sea’s seabird populations linked to those in the California Current?: Implications for local mechanisms driving population trends

The marine bird community of the Salish Sea is composed of over 70 bird species that are relatively abundant and highly dependent upon marine resources for survival but their relative abundance changes dramatically throughout the year due to differences in the timing and extent of residency by migratory, over-wintering and local breeding seabird populations. Evidence suggests that several over-wintering species in particular have declined precipitously over the last several decades but that not all species are exhibiting declining populations. To provide additional insights into the health of Salish Sea seabird populations, we examine trends in breeding seabird populations (alcids and cormorants) over the past 15 years. For these same species, we also compare intra-specific seabird trends between the Salish Sea and California Current to determine whether or not the observed population changes are unique to the Salish Sea or part of a larger California Current trend. Finally, we assess the degree to which these marine ecosystems and their bird populations are linked by examining species-specific correlations between the California Current and Salish Sea. To gain insights into mechanisms driving Salish Sea population changes we qualitatively compare our breeding season results with results from our previous work on over-wintering populations. This comparison provides insights into various life history traits, such as diet and local breeding, on observed population trends