Wintering and breeding distributions of Black Oystercatchers (Haematopus bachmani): Long-term trends and the influence of climate

Black Oystercatchers (Haematopus bachmani) are argued to be at risk from global climate change as rising sea levels could threaten their coastal habitat. However, population estimates have doubled to ~15 000 since 1994. This has been attributed to improvements in survey methods rather than to population trends, which remain uncertain. I assessed trends and climatic influences on winter abundance (Christmas Bird Counts, 1975/1976 – 2015/2016) and numbers of breeding pairs (British Columbia breeding surveys, 1962 – 2014). Winter counts were stable or increasing across the species' range. Numbers of breeding pairs were stable in British Columbia, but were lower following the warm phase than the cool phase of the El Niño Southern Oscillation. Although new challenges may arise as the climate continues to change, Black Oystercatcher populations appear resilient to current environmental and anthropogenic challenges.