Spatiotemporal patterns of red fox scavenging in forest and tundra: the influence of prey fluctuations and winter conditions

Gjermund Gomo,Nina E Eide,Jenny Mattisson,Morten Odden,Lars Rød-Eriksen

doi:10.1007/s13364-021-00566-7

Gjermund Gomo, Nina E Eide + Show 3 more

Open Access

https://doi.org/10.1007/s13364-021-00566-7

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Abstract

Concern has been raised regarding red fox (Vulpes Vulpes) population increase and range expansion into alpine tundra, directly and indirectly enhanced by human activities, including carrion supply, and its negative impact on native fauna. In this study, we used cameras on bait stations and hunting remains to investigate how spatiotemporal patterns of red fox scavenging were influenced by abundance and accessibility of live prey, i.e., small rodent population cycles, snow depth, and primary productivity. We found contrasting patterns of scavenging between habitats during winter. In alpine areas, use of baits was highest post rodent peaks and when snow depth was low. This probably reflected relatively higher red fox abundance due to increased reproduction or migration of individuals from neighboring areas, possibly also enhanced by a diet shift. Contrastingly, red fox use of baits in the forest was highest during rodent low phase, and when snow was deep, indicating a higher dependency of carrion under these conditions. Scavenging patterns by red fox on the pulsed but predictable food resource from hunting remains in the autumn revealed no patterns throughout the rodent cycle. In this study, we showed that small rodent dynamics influenced red fox scavenging, at least in winter, but with contrasting patterns depending on environmental conditions. In marginal alpine areas, a numerical response to higher availability of rodents possible lead to the increase in bait visitation the proceeding winter, while in more productive forest areas, low availability of rodents induced a functional diet shift towards scavenging.

Highlights

Ecosystems are subsidized to a varying degree with energy, matter, and organisms from neighboring sources (Polis et al 1997; Leroux and Loreau 2008), or by anthropogenic activity (Oro et al 2013)
This study presents novel insight into spatial and temporal patterns of red fox scavenging and its relationship with small rodent dynamics, snow depth, and habitat in central Fennoscandia
We addressed two hypotheses regarding red fox scavenging that were based on differences in the relative

Summary

Introduction

Ecosystems are subsidized to a varying degree with energy, matter, and organisms from neighboring sources (Polis et al 1997; Leroux and Loreau 2008), or by anthropogenic activity (Oro et al 2013) Such subsidies can cause an increase in abundance and distribution of opportunistic species which, in turn, may result in trophic cascades altering communities, Communicated by: Dries Kuijper. In Fennoscandia, both direct and indirect factors connected to anthropogenic activity have been linked to red fox range expansion and increased abundance. Red foxes might benefit from increased availability of anthropogenic food resources through the expansion of human settlements, cabin areas, and infrastructure (Gallant et al 2020; Rød-Eriksen et al 2020). Remains from hunting of ungulates are another source of food that can subsidize scavengers during harvest periods (Wikenros et al 2013; Gomo et al 2017)

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