At-sea distribution and foraging behaviour of two North Pacific seabirds revealed through GPS tracking

Successful conservation of seabirds requires identifying at-sea foraging areas and drivers of habitat use patterns. Here, I used GPS tracking technology to provide insights into the foraging behaviour of Cassin’s auklets (Ptychoramphus aleuticus) and rhinoceros auklets (Cerorhinca monocerata) breeding in British Columbia, Canada. I found that inter-annual variation in Cassin’s auklet habitat use (2014, 2015, and 2017) was best explained by sea surface temperature, a dynamic oceanographic feature, while chlorophyll a concentrations and bathymetric features were poor predictors of habitat use. I found low spatiotemporal variation in movement patterns of rhinoceros auklets breeding at the Lucy Islands, mirroring stability in surrounding oceanographic conditions and diet composition, but high variability in the movement patterns of rhinoceros auklets at Pine and Triangle Islands. Overall, my results show that oceanographic conditions drive habitat use patterns of both species, and highlights the need to develop dynamic management strategies for successful conservation of at-sea habitat.