Abstract
In the boreal forest, the red fox (Vulpes vulpes) is a key species due to its many strong food web linkages and its exploitation of niches that form in the wake of human activities. Recent altitudinal range expansion and a perceived population increase have become topics of concern in Scandinavia, primarily due to the potential impacts of red foxes on both prey and competitor species. However, despite it being a common species, there is still surprisingly little knowledge about the temporal and spatial characteristics of its population dynamics. In this study, we synthesized 12 years of snow-track transect data covering a 27,000-km2 study area to identify factors associated with red fox distribution and population dynamics. Using Bayesian hierarchical regression models, we evaluated the relationships of landscape productivity and climate gradients as well as anthropogenic subsidies with an index of red fox population size and growth rates. We found that landscapes with high human settlement density and large amounts of gut piles from moose (Alces alces) hunting were associated with higher red fox abundances. Population dynamics were characterized by direct density-dependent growth, and the structure of density dependence was best explained by the amount of agricultural land in the landscape. Population equilibrium levels increased, and populations were more stable, in areas with a higher presence of agricultural lands, whereas density-dependent population growth was more prominent in areas of low agricultural presence. We conclude that human land use is a dominant driver of red fox population dynamics in the boreal forest. We encourage further research focusing on contrasting effects of anthropogenic subsidization on predator population carrying capacities and temporal stability, and potential impacts on prey dynamics.
Highlights
Human land use has dramatically altered the structure and dynamics of natural habitats in biomes across the world (Walther et al 2002; Foley et al 2005)
We show that the spatiotemporal dynamics of red foxes are closely interrelated with human landscape modification and activities
We found that negative feedback processes of first-order dynamics dominated the structure of temporal variation in the population index
Summary
Human land use has dramatically altered the structure and dynamics of natural habitats in biomes across the world (Walther et al 2002; Foley et al 2005). Red fox population densities in the boreal forest vary considerably among years according to the multi-annual population cycles of its main prey, microtine voles (Lindström 1982) This pattern is more profound with increasing latitude and altitude (Englund 1980a; Lindén 1988), and the degree of stability in the red fox population probably relates to both the availability of alternative prey in the low phase of the vole cycle and density-dependent, negative feedback mechanisms from predation on voles (Erlinge et al 1983). We contrast potential effects of anthropogenic subsidies and land use to natural productivity gradients on red fox abundance and temporal variability in population growth structure. We discuss potential mechanisms underlying the observed patterns as well as potential consequences of anthropogenic subsidization of generalist predators on the boreal forest ecosystem
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