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. Carrion can act as a buffer when food resources are low, and some terrestrial species use the marine environment for cross-ecosystem resource subsidies. We present an overview of scavenging as a foraging strategy in the Arctic marine environment and examine the contribution of prey provided by polar bears to the Arctic scavenging assemblage. As obligate predators of seals, polar bears contribute a substantial amount of carrion to the marine ecosystem, particularly to the sea ice surface where it is accessible for seasonal scavenging opportunities. 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 106 kg/year of usable carrion biomass for scavengers across their range, equivalent to 1.55 x 108 MJ of energy. Eleven vertebrate species are known to scavenge polar bear kills, and an additional 7 are potential scavengers. While foraging associations with polar bear kills for some species are better understood, others are scarce or undocumented. We provide an overview of what is known about the role of polar bears as carrion providers, the network of scavenging species on the sea ice, and the possible consequences of trophic downgrading in this ecosystem and recipient ecosystems.

Identifying areas of high-quality habitat is often a critical first step for the recovery and management of species of conservation concern, yet patterns of high density in an area may not always correspond with high-quality habitat. On San Clemente Island (SCI), the island fox subspecies (Urocyon littoralis clementae) has been monitored annually since 1988 to track long-term population trends. Annual density estimates in most habitat types across the island range from 2–13 foxes/km2, yet unusually high estimates have repeatedly approached 50 foxes/km2 in a unique sand dune habitat area. Although sand dune habitat is restricted to one small area on the island, these estimates suggest sand dune habitat supports one of the highest population densities of any fox species in the world, and it may support > 5% of the SCI fox population. This prompted our investigation to determine if SCI foxes captured in sand dune habitat maintained home ranges within this habitat type. We hypothesized that island foxes used sand dune habitat as an important foraging area while maintaining home ranges centralized in adjacent habitat types, which likely inflated density estimates for sand dune habitat. Between January–July 2018, we used Global Positioning System collars to track the movements of 12 island foxes captured in the sand dune habitat area. Contrary to our initial predictions, we found that island foxes captured in the sand dune habitat area do maintain home ranges and core areas centralized in sand dune habitat. All 12 island fox home ranges estimated contained >50% sand dune habitat in either their 50% or 95% fixed kernel density estimate (KDE) home range, and island foxes were 3.14 times more likely to use active sand dune habitat when compared to the second most abundant habitat type, maritime desert scrub (Adjusted β = 3.14, 95% CI = 3.07–3.12).