Relative efficiency of two models of snap traps for sampling boreal small mammals
Studies on the relative efficiency of commercially-available snap trap models are rare, and results between studies are often contradictory. We report that the performance of 2 trap models in capturing boreal small mammals differed significantly. Caution is urged when mixing trap models in monitoring programs or interpreting results obtained with different traps. We encourage similar comparisons with different small mammal assemblages as trap performance is likely species specific.
Snap traps have long been a cost-effective means of monitoring small mammal (<60 g) diversity and abundance, particularly at larger spatial or temporal scales. Yet, studies on the relative efficiency of snap trap models are surprisingly rare in the literature. We assessed the relative efficacy of Victor Mouse and Woodstream Museum Special snap traps for sampling boreal small mammals. Paired traps were set for 2–3 nights at 40–50 trapping stations at each of 110 sites, for a total sampling effort of 28,910 trap nights. We captured 1,013 small mammals representing 13 species. Overall, Museum Special traps caught almost twice as many small mammals as Victor traps. There was no difference in the sex or age-class of the overall capture in the 2 trap models. However, Museum Special traps were triggered without capturing a small mammal 31% more often than Victor traps. Results for the six most frequently captured species (Myodes rutilus, Microtus pennsylvanicus, Microtus oeconomus, Microtus xanthognathus, Peromyscus maniculatus, and Sorex cinereus) mirrored those for overall captures. Moreover, the percent of the total capture in Museum Special traps ranged between 57–80% for each of the above species, indicating species-specific responses to trap type. Our data further demonstrate the superior ability of Museum Special traps to capture boreal small mammals compared to Victor traps, which is likely attributed to a more sensitive trigging mechanism. Implications of our results suggest caution when mixing trap models in monitoring programs, or when interpreting results obtained with different trap models. We encourage similar comparisons in different biomes with different small mammal assemblages as trap performance is likely species specific.