Intra‐species differences in impacts of climate change: A case study of the hooded seal ( Cystophora cristata )

The Arctic is warming nearly four times faster than the global average, but the rate of change is not uniform across the region. Wide‐ranging Arctic species are exposed to variable environmental conditions across their range, but it remains unclear how different climate change regimes are affecting populations within the same species that have become exposed to different conditions and how each population may respond in the future. In this study, we investigated how environmental changes in the Greenland Sea (GS) have influenced foraging behavior and diet of GS hooded seals (Cystophora cristata) over recent decades, and evaluated how future climate scenarios may affect them. We then compared these findings with recently published results on hooded seals from the Northwest Atlantic (NWA) stock, placing them in the broader context of Arctic ecosystem dynamics. Specifically, we analyzed changes in (1) foraging distribution and habitat use based on a two‐decade tracking time series (1992–1993 and 2007–2008) from GS hooded seals and (2) diet, using carbon and nitrogen stable isotopes from blubber samples collected in 2007 and 2022. We also projected future suitable foraging habitats under the SSP5‐8.5 climate scenario. Our results show that while GS hooded seals have maintained consistent habitat preferences and diets over the past two decades, their foraging areas have shifted eastward, rather than northward as was seen for the NWA seals—despite northward shifts in their breeding and molting grounds. Suitable foraging habitats of the future are projected to expand and continue shifting eastward. This pattern is unexpected for an ice‐associated Arctic species, and contrasts projections for the NWA stock. Although it is uncertain whether hooded seals possess sufficient behavioral or physiological plasticity to cope with future climate‐driven changes, our findings underscore the importance of considering population‐level behavioral heterogeneity when assessing species‐wide responses to environmental change.