The Efficiency of Live-Capture Traps for the Study of Red Fox (Vulpes vulpes) Cubs: A Three-Year Study in Poland

SIMPLE SUMMARY: Wild canids may be captured for a variety of purposes, including, for example, scientific research, conservation or relocation to new sites. The use of conventional live-capture traps (also referred to as cage traps), which involve safe trapping techniques, may be limited by the age of the target animal, landscape structure, proximity to areas intensively used by people and regulations at the national or regional level. Live-trapping with cage traps is the only legal method for capturing juvenile red foxes in Poland. However, little is known about the factors that can affect capture efficiency of these trapping devices. In this research, we developed standard operating procedures (SOPs) for the capture of fox cubs using cage traps and camera traps. We also identified factors that may facilitate or hamper the success of cage traps. The selectivity (total number of trapped red fox cubs per total number of trapped animals) of live-capture traps (91.4%) and the probability of capturing one cub per night (70.2%) were high. In the vicinity of human settlements, fewer cubs explored and entered cage traps. Capture efficiency was also affected by the weather, i.e., it increased in poor weather conditions (e.g., during rain, thunderstorms or ground frost). None of the trapped animals were injured. Live-trapping with cage traps can be an effective and safe alternative to other devices used to trap juvenile foxes. However, capture-efficiency is affected by trappers’ experience and a range of factors including weather conditions and distance to human settlements. ABSTRACT: Safe and efficient techniques for the live capture of carnivores are limited. In this study, we identified some of the factors that could affect the success of capturing red fox cubs with live capture traps (also known as cage traps). During a three-year period, we analysed 32 captures of 25 fox cubs (1.3 captures/fox). We assessed the impact of the following factors: sex of animals, month of trapping, weather conditions recorded for each trap-night, the willingness of cubs to explore and enter cage traps, the researchers’ activity around den complexes before trapping and distances to the nearest village or farm. The overall trap rate (32 captures, including recaptured cubs) and the trap rate for individual cubs (25 captures) was 11.2 cubs/100 trap-nights and 8.7/100 trap-nights, respectively. Animals other than foxes were captured only three times, thus the selectivity of the cage-trapping method was high (32/35 = 91.4%). The probability of capturing one cub per night was 70.2% (32 cubs/47 nights). Cubs inhabiting dens in the vicinity of human settlements were less likely to explore and enter traps. Vixens were more likely to relocate their litters if the activity of the staff setting the traps was intense at the trapping site. The success of trapping was higher during poor weather as, for example, during rain or thunderstorms. None of the trapped animals suffered any injuries. Whereas cage trapping can be an effective and safe capture method for juvenile foxes, capture efficiency is affected by the experience of the trappers and a range of other factors including weather and distance to human settlements.