Estimating red fox density using non-invasive genetic sampling and spatial capture\u2013recapture modelling

Richard Bischof,Ida Pernille Øystese Andersskog,Nina E Eide,Lars K Lindsø,Lars Rød-Eriksen,Øystein Flagstad,Kristine Roaldsnes Ulvund,Pierre Dupont

doi:10.1007/s00442-021-05087-3

Richard Bischof, Ida Pernille Øystese Andersskog + Show 6 more

Open Access

https://doi.org/10.1007/s00442-021-05087-3

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Abstract

Spatial capture–recapture modelling (SCR) is a powerful tool for estimating density, population size, and space use of elusive animals. Here, we applied SCR modelling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016–2018) and southern Norway (2017–2018). Estimated densities were overall lower in the central study area (mean = 0.04 foxes per km2 in 2016, 0.10 in 2017, and 0.06 in 2018) compared to the southern study area (0.16 in 2017 and 0.09 in 2018). We found a positive effect of forest cover on density in the central, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover. Estimated mean home-range size in the central study area was 45 km2 [95%CI 34–60] for females and 88 km2 [69–113] for males. Mean home-range sizes were smaller in the southern study area (26 km2 [16–42] for females and 56 km2 [35–91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modelling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space use.

Highlights

Reliable information on animal population status, including population size and density, is crucial for wildlife research and management (Kämmerle et al 2018)
The goal of the present study is to assess the combination of non-invasive genetic sampling with spatial capture–recapture for estimating red fox density, and explore the role of individual and spatial variables on density, space use, and detectability
To test for a relationship between red fox density and available forest habitat, as suggested by previously reported habitat preferences of the red fox (Cagnacci et al 2004; Svendsen 2016; Van Etten et al 2007), we considered an effect of forest cover as a spatial predictor of density (Molina et al 2017)

Summary

Introduction

Reliable information on animal population status, including population size and density, is crucial for wildlife research and management (Kämmerle et al 2018). The red fox (Vulpes vulpes) is a highly adaptable and opportunistic mesopredator with a broad ecological niche and variable diet, including both wild and domestic vertebrates (Dell'Arte et al 2007; Killengreen et al 2011) It is the most widely distributed carnivore in the world and is commonly found in a wide array of habitats. The species’ ongoing geographic expansion is of management concern due to deleterious effects on populations of other species This includes intraguild competition with arctic fox (Vulpes lagopus; Frafjord et al 1989), and predation on threatened species like the lesser white-fronted goose (Anser erythropus; Aarvak et al 2017), and game species like forest birds (Doherty et al 2016; Jahren 2017; Skrede 2016; Smedshaug et al 1999). The red fox is a vector of zoonotic pathogens that can pose risks for domestic

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