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

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 collected from 58 trappers (35,774 trap-nights) in a 660-km(2) 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 different 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.