Variable responses of seabirds to recent North Pacific warming

The extreme and persistent 2013-2015 warming of the North Pacific (including The Blob, other regional anomalies, and ENSO effects) is expected to affect marine ecosystems, but to date no large-scale synthesis has been attempted. To test for warming effects, we investigated the breeding success of 18 different species representing ~40 time series from the Gulf of California to the Eastern Bering and Japan Sea. We first evaluated how seabird breeding success in 2014 (and 2015 when possible) varied from baseline values: in 2014, seabirds in the Japan Sea and Gulf of California showed strongly negative anomalies, whereas seabirds in the Aleutian Islands/Bering Sea showed positive anomalies, and birds from the central Gulf of Alaska to central California Current did not vary much from long-term averages. This pattern is unique, as seabird responses to large-scale climate variability are typically more consistent between species and regions. Second, we related breeding success to local and basin-scale temperature anomalies. In some locations, pathways of response are clear, from Blob/ENSO-scale warming to local warming (to local food webs and seabirds), but elsewhere other factors (e.g., upwelling in the northern CCS) ameliorated large-scale warming resulting in lessened effects on the ecosystem.