A Simple Permanent Livetrap Plot for Shrews

Abstract

The author has experienced considerable difficulty in successfully live-trapping shrews in the boreal forest of eastern Manitoba. Using the Sherman livetrap it was found that unless the traps were examined at hourly intervals, the mortality in Sorex einer ens and S. arcticus was 100 per cent. Recently however the Sherman trap was replaced by tumble-in traps constructed by removing the tops of clean imperial-quart oil cans. These are then imbedded grid fashion on the plot flush with the ground level and baited with raw liver or ground beef. Captured animals are easily removed by removing the trap and inverting it into a plastic food bag where the animal is either marked and released or transported to the field laboratory. In the majority of cases, animals taken by this method were alive and well after remaining in the traps until the following morning. When the operator wishes to terminate trapping for any period, the oil cans are merely inverted in the hole so that the bottom of the can remains flush with the ground. The method has the advantage of less mortality even in light rainstorms and the cost of the trap is negligible. It further eliminates transporting the heavy and bulky Sherman trap. Juvenile Microtus and Clethrionomys can also be successfully taken in this manner, but a deeper trap is required for such forms as