Interdecadal shifts in seabird distributions relative to the velocity of climate change in the Northeast Pacific Ocean: a long-term observational study

Climate change is altering marine habitats, prompting shifts in the distribution of marine organisms as they seek to occupy preferred environmental conditions. This study examines whether seabird redistributions in the Northeast Pacific Ocean correspond to spatial displacements in sea surface temperature isotherms, also known as the velocity of climate change (VoCC). Using 47 yr (1975-2021) of breeding season seabird observations archived in the North Pacific Pelagic Seabird Database, we applied Vector Autoregressive Spatio-Temporal modeling to analyze distributional changes for 9 taxonomic groups. We assessed leading edge, range core, center of gravity, and area-occupied metrics, and related these to VoCC. Our results reveal substantial decadal variation in seabird distributions, particularly during 2 periods of major oceanographic change: 1991-2010, when isotherms shifted southeastward in the Gulf of Alaska, and 2001-2021, when isotherms shifted strongly northwestward in both the Gulf of Alaska and Eastern Bering Sea. Most seabird groups expanded their range eastward during the first period and shifted westward or northward during the latter. The magnitude of longitudinal shifts generally exceeded that of latitudinal shifts. Increased area occupied was noted for auklets, murres, and shearwaters in the Bering Sea, corresponding to northward leading edge movements. Our findings highlight complexity in seabird distributional responses to climate-driven habitat changes in the Northeast Pacific.