Evidence of anthropogenic subsidisation of red foxes in a national park important for breeding wading birds

Abstract The red fox ( Vulpes vulpes ) is a generalist mesopredator found throughout the UK. It has been linked to national declines in native wildlife, especially ground-nesting birds such as waders. In the New Forest National Park, nest predation and poor chick survival is primarily responsible for low breeding success of Eurasian curlew ( Numenius arguata ), a species of high conservation concern. To reduce predation losses, foxes are lethally controlled by wildlife managers. Here, we identified the major food resources that are being exploited by foxes in the New Forest area and examined temporal and spatial patterns in the presence of specific food categories, with special reference to anthropogenic food. Stomachs from foxes culled in curlew breeding areas were collected from April 2021 - July 2022 and the contents of these stomachs were quantified. Foxes exhibited a highly varied diet with no single food category predominating. Anthropogenic food comprised 14% of the overall diet, with its presence predicted by proximity to human settlements and other infrastructure. We also estimated the total annual volume of anthropogenic food consumed by the fox population and by extension how many individual foxes this volume of food could support in isolation. According to these calculations, at present the number of foxes subsidised by anthropogenic food is approximately 64.8% (50.2–79.7%) of those removed by culling per year. Our findings highlight that better local food sanitation and education should become important parts of a more holistic management approach to reduce the burden of fox predation experienced by breeding waders.