Capturing beavers in box traps

Abstract

Box traps have been widely used in North American wildlife research studies for live capture of terrestrial animals such as coyotes (Canis latrans) (Kamler et al. 2002, Way et al. 2002), foxes (Vulpes spp.) (White et al. 1991, Kamler et al. 2002), lynx (Lynx canadensis) (Mowat et al. 1994, Kolbe et al. 2003), and raccoons (Procyon lotof) (Gehrt and Fritzell 1996), but little is known about the efficacy of box traps to capture aquatic species such as beavers (Castor canadensis}. Beavers typically are live-captured with snares (McKinstry and Anderson 2002), suitcase-type traps like the Hancock (Hodgdon 1978) and Bailey (Buech 1983) designs, or, more recently, hand nets (Rosell and Hovde 2001). In some states, like Massachusetts, snares are illegal. Snares and Hancock and Bailey traps can be camouflaged, partially or fully submerged, and hidden from beavers. It is not known whether beavers will enter box traps, which are more difficult to conceal, on a consistent basis or whether capture would be biased to specific age or sex classes. In a review on methods of live-trapping beavers, Rosell and Kvinlaug (1998) reported that a variety of box trap designs have been used in Russia, Germany, Norway, Finland, and Sweden, primarily for nuisance beaver control, but very little quantitative information was available on the capture efficiency and sex and age composition of beavers caught with these traps. There has been no report of the use of box traps to capture beavers in North America. In a recent review of trapping techniques for mammals, Powell and Proulx (2003) do not include beaver in their list of species that can be captured with box traps. In 2001-2003, we modified and used commercially available box traps to capture beavers for a study on demography and movements of beavers across a suburban-rural gradient in 3 study areas in Massachusetts. Here we report on capture success of beavers in box traps, explain box trap designs and modifications, describe our field sets, and present costs of purchasing and modifying traps.