Factors affecting trapping success of red fox Vulpes vulpes, stone marten Martes foina and pine marten M. martes in France

Abstract

Trapping records are often used to monitor long-term trends of small carnivore populations. However, many factors, not related to abundance, may affect capture rates. In this study, we examined whether trapper experience, trapping effort and trapping methods significantly affect capture rates of red fox Vulpes vulpes, stone marten Martes foina and pine marten M. martes. Data were col lected from 58 trappers (35,774 trap-nights) in a 660-km2 study area during one trapping season. The main trapping methods used for foxes and martens with different types of traps were identified by multiple correspondence analyses on 424 trap sites. Generalised linear modelling showed that trapping methods, the length of time traps were set in the same place, trapper experience and the presence of captures in neighbouring trap sites significantly affect capture rates of foxes and martens. Given the high variability of capture rates among differ ent combinations of these factors (0-3.4 captures/100 trap-nights for fox and 0.6-7.8 captures/100 trap-nights for martens), a separate trapping index should be calculated to detect trends in small carnivore populations.

How effective and selective is traditional Red Fox snaring?

“…Trapping efficiencies were highest for Collarum® (5.6-18.8 foxes per 1,000 trap-nights) and Belisle® (3.1-24.2 foxes per 1,000 trap-nights) (Muñoz-Igualada et al 2008). In France, Ruette et al (2003) obtained efficiencies of 1.2-17.9 foxes per 1,000 trap-nights and 0-31.7 foxes per 1,000 trap-nights, using neck or leg snares, respectively. Efficiencies calculated for Australia and US using different kind of snares varied from a minimum of 2.1 to as much as 21.6 foxes per 1,000 trap-nights (Litvaitis et al 1984, Meek et al 1995, Bubela et al 1998, Fleming et al 1998, Shivik et al 2005.…”

“…Efficiency obtained in this study falls within the ranged observed by other authors in Europe using similar devices. Ruette et al (2003) argues trapping efficiency is affected by fox density, habitat type, the device used, but also by trapper experience in setting devices. Ferreras (2007) found that cage-trapping efficiency in Spain could range from 3 to 10 foxes per 1,000 trap-nights.…”

“…The better option would be regularise these activities in each region and develop a corps of professional predator culling personnel as recommended by the Conferencia Sectorial de Medio Ambiente (2011). The need for trained persons is clear since for trapping methods to be successful (increased extrinsic selectivity) the experience of the person who manages them is fundamental (Ruette et al 2003). Phillips (1996) and Kirkwood et al (2005) point out that the experience of the trapper is crucial to minimize unwanted captures of animals not subject to control.…”

Assessing cumulative impacts of forest development on the abundance and distribution of furbearers.

“…For this study, trapper experts can assist with the on ground validation o f model results and link habitat change to population abundance in the form of trapping records (Smith et al 1984, Ruette et al 2003. Professional experts may provide a more general perspective on the habitat requirements o f individual species.…”

“…Expert-based wildlife studies may serve as an alternative to empirical-based research, particularly when the cryptic behaviour o f many furbearer species makes them difficult to study (Ruette et al 2003). Where empirical data are lacking, expert knowledge can provide useful insights on cumulative impacts and their influence on the distribution and abundance of furbearers.…”