Andrew Derocher, Nicholas Pilfold, James Roth, Evan Richardson, David McGeachy

Scavenging is a foraging strategy widely used across the animal kingdom and apex predators provide a large amount of energy in a food web. In the harsh environmental conditions of the Arctic, apex predators such as polar bears (Ursus maritimus) can provide scavenging opportunities for many species. We present an overview of scavenging in the Arctic marine environment and examine the contribution of prey provided by polar bears to the Arctic scavenging assemblage. We estimated that each adult polar bear kills an average of 1,001 kg of marine mammal biomass annually, and given preferential feeding of blubber and abandonment of carcasses, we estimate that 30% of the biomass is left as usable carrion. Consequently, polar bears provision approximately 7.0 x 10^6 kg/year of usable carrion biomass for scavengers across their range, equivalent to 1.55 x 10^8 MJ of energy. While foraging associations with polar bear kills for some species are better understood, others are scarce or undocumented. To provide an understanding of the scavengers that benefit from polar bear kills, we monitored experimentally placed seal carcasses with remote cameras on the sea ice near Pond Inlet, Nunavut and Churchill, Manitoba. To date, we have detected 11 species across 49 experimentally placed carcass sites, and we intend to monitor an additional 10 sites in Pond Inlet in 2026. This is the first study to document the network of scavenging species on the sea ice, as no previous experimental research has explored this topic. We take a novel approach to assess the impacts of climate change in the Arctic and consequences for the ecosystem if polar bears are lost.