Reproductive responses to spatial and temporal prey availability in a coastal Arctic fox population

Abstract

Summary1. Input of external subsidies in the Arctic may have substantial effects on predator populations that otherwise would have been limited by low local primary productivity. 2. We explore life-history traits, age-specific fecundity, litter sizes and survival, and the population dynamics of an Arctic fox (Vulpes lagopus) population to explore the influence of the spatial distribution and temporal availability of its main prey; including both resident and migrating (external) prey resources. 3. This study reveals that highly predictable cross-boundary subsidies from the marine food web, acting through seasonal access to seabirds, sustain larger local Arctic fox populations. Arctic fox dens located close to the coast in Svalbard were found to have higher occupancy rates, as expected from both high availability and high temporal and spatial predictability of prey resources (temporally stable external subsidies). Whereas the occupancy rate of inland dens varied between years in relation to the abundance of reindeer carcasses (temporally varying resident prey). 4. With regard to demography, juvenile Arctic foxes in Svalbard have lower survival rates and a high age of first reproduction compared with other populations. We suggest this may be caused by a lack of unoccupied dens and a saturated population.

Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra

“…We found that both their diet and annual productivity were strongly affected by cyclic fluctuations in lemming abundance, as found elsewhere [69][70][71]. Even though lemming peaks may have been less pronounced during the 2000s than in the previous decade on Bylot Island, this had no long-term effect on fox productivity.…”

Snowmobile impact on diurnal behaviour in the Arctic fox

“…Additionally, food resource availability differs between the sites. Arctic foxes in Svalbard live in an ecosystem lacking small rodents and competitors (Fuglei et al 2003;Eide et al 2012), which is not the case in Russia (Pokrosvky et al 2014;Sokolov et al 2016). The scarcity and unpredictability of food resources in Svalbard makes the foxes behave as generalist scavengers, feeding opportunistically (Fuglei et al 2003;Eide et al 2012).…”

“…Arctic foxes in Svalbard live in an ecosystem lacking small rodents and competitors (Fuglei et al 2003;Eide et al 2012), which is not the case in Russia (Pokrosvky et al 2014;Sokolov et al 2016). The scarcity and unpredictability of food resources in Svalbard makes the foxes behave as generalist scavengers, feeding opportunistically (Fuglei et al 2003;Eide et al 2012). One study in Svalbard showed that Arctic foxes had huge variation in fat content during winter (from 5% to 40% of skinned body mass; Prestrud & Nilssen 1992), indicating a need for an opportunistic search for food.…”

“…The fact that Arctic foxes in Varanger used the camera-traps mainly during the night was explained by the presence of scavengers, such as golden eagle (Aquila chrysaetos), competing and excluding the Arctic fox from visiting the camera-traps during the light part of the day (Killengreen et al 2012). Since Arctic foxes in Svalbard and at the Russian sites lack competitors and predators (Fuglei et al 2003;Eide et al 2012;Pokrosvky et al 2014;Sokolov et al 2016), and live under similar light conditions in late winter, we expected no differences in diurnal activity documented by camera-traps in Svalbard and at the Russian sites.…”

Relationship Between Tooth wear and Age in the Japanese Black Bear in Hiroshima Prefecture, Japan

“…We observed a maximum age of 8 years in our population, while the oldest individuals were 7 or 8 years-old in other Canadian populations (Bradley et al 1981, Hiruki andStirling 1989), 8 years-old on Saint Lawrence Island in Alaska (Fay and Rausch 1992), and 10 years-old in Iceland (Hersteinsson 1992) and Svalbard (Eide et al 2012). This indicates that maximum longevity seems to be a rather constant parameter across arctic fox populations.…”