Selectivity and injury risk in an improved neck snare for live-capture of foxes.

Abstract

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., non-experimental 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 non-experimental 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 non-experimental 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.