Rules of attraction: the role of bait in small mammal sampling at high altitude in South Africa

Abstract

Baits or lures are commonly used for surveying small mammal communities, not only because they attract large numbers of these animals, but also because they provide sustenance for trapped individuals. In this study we used Sherman live traps with five bait treatments to sample small mammal populations at three high-altitude sites (>1700 m) in the Sneeuberg Mountain Complex of the Eastern Cape Province, South Africa.We investigated the influence of bait treatment on three parameters commonly recorded in small mammal surveys. In addition, we investigated how different bait treatments vary in measuring species richness using the Chao 2 species richness estimator together with rarefaction curves. Overall, 12 small mammal species were sampled. A combination of birdseed and banana captured the highest number of species (11) but the most successful bait overall was peanut butter and oats (greatest number of captures, recaptures, number of individuals and highest Shannon diversity). The Chao 2 richness estimator indicated that four of the five bait treatments reached their sampling capacity. Rarefaction curves indicated that all bait treatments are similar with regard to species accumulation. This could possibly be explained by odours left behind in traps as even un-baited traps (i.e. controls) captured seven different small mammal species. We conclude that the most suitable bait for surveying small mammals at high altitude in South Africa is peanut butter and oats. However, using peanut butter and oats in combination with other bait treatments will improve estimates of diversity when surveying small mammal communities.

Key words:

• bait treatments
• rarefaction curves
• small mammal trapping
• non-parametric species richness estimators