Remote sensing, snow modelling, survey data and Indigenous Knowledge show how snow and sea-ice conditions affect Peary caribou (Rangifer tarandus pearyi) distribution and inter-island and island–mainland movements

Abstract

Accelerated warming of the Arctic has reduced sea ice and has increased the occurrence of winter extreme events like rain-on-snow and storms that impact snow-cover densification, affecting Peary caribou (Rangifer tarandus pearyi) seasonal movements and grazing conditions. We used caribou movements between Banks, Melville and Victoria islands and mainland Canada, documented from Indigenous Knowledge, to assess whether spatiotemporal trends in sea-ice anomalies (1983–2019) can be used as an indicator of caribou movement. We used the SNOWPACK model to evaluate how foraging conditions (as indexed by simulated snow properties) contribute to the prediction of caribou presence. Our results suggest that changes in sea-ice anomalies over time have impacted caribou crossings between islands: caribou no longer use areas with less sea ice whilst they continue to use areas with more sea ice. Our model evaluation shows that, when the simulated snow conditions are paired with other environmental variables, the ability of models to predict Peary caribou occurrence on land was enhanced across Banks and Melville islands. Overall, the land models suggest that caribou are more likely to occupy areas with lower density of snow accumulation and a majority of forb tundra with dwarf shrubs for Banks Island and cryptogam tundra, rush and grass for the Melville Island Complex. Our results suggest that future work monitoring changes in sea-ice and snow conditions will be important for understanding the impact of climate change on the distribution of Peary caribou in the western Arctic.