Search

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.

Neck snares have been considered valuable for the control of canids and to catch canids for scientific purposes, but they have been criticized for perceived low target selectivity and poor animal‐welfare. In 2006, we designed an experimental passive neck snare for live‐capture of red fox (Vulpes vulpes), in which postcapture selectivity was addressed by means of a breakaway device and minimum loop size. In field trials during 2007–2009, performance was compared against snare types already in use (i.e., nonexperimental snares) by full‐time game managers at 34 different sites in the United Kingdom (UK). Red fox, European badger (Meles meles), and brown hare (Lepus europaeus) made up 91% of 1,296 captures. Capture rate of red fox (n= 359) was similar in experimental and nonexperimental snares (6.6 captures/1,000 snare‐days). The percentage of European badgers that escaped after capture was 39% (n= 76) in experimental and 14% (n= 36) in nonexperimental snares. The percentage of brown hares that escaped after capture was 33% (n= 384) in experimental snares compared with 18% (n= 311) in nonexperimental snares, but it was further improved to 68% (n= 192) in a second version of the experimental snare with increased minimum loop size. In experimental snares, 31% of captured badgers, 10% of captured brown hares, and 6% of captured foxes escaped by opening the breakaway device. The study showed that careful snare design can improve selectivity without sacrificing effectiveness. For restrained animals, however, condition was also strongly influenced by operating practices. Entanglement with nearby objects was the principal determinant of externally visible injury or death in restrained animals. Given a well‐designed snare, entanglement can largely be avoided through choice of snare location as described in UK best practice guidelines. © 2012 The Wildlife Society.

Abstract:American mink (Neovison vison) are an ecologically damaging invasive species where they have been introduced in Europe. Effectiveness of mink population control by trapping has been difficult to assess, without knowing how efficiently mink are caught by traps or detected by other methods. Use of track-recording rafts to detect mink and guide trapping effort has proved efficient and leads to a supposition that no detection indicates absence of mink. To draw this conclusion with any confidence requires a measure of detectability. We applied occupancy models to data from an earlier study to estimate detectability of individual American mink on track-recording rafts. Estimated detectability of individual mink, per raft, and 2-week check period varied between 0.4 in late summer and 0.6 in late autumn. By inference, risk of failing to detect a mink that was present would be <5% given 4–6 independent opportunities to detect it. These opportunities could be created either by using a raft spacing that ensured multiple detections of each mink or by monitoring rafts through a succession of check intervals. Within certain simple constraints, raft location did not contribute substantially to detection probability. These findings will allow field operators, strategists, and funders to assess with confidence the success of efforts to control mink density. We expect the estimation of individual detectability to be similarly valuable in population control or eradication of other species.