A comparison of two types of trap for sampling dung beetle populations (Coleoptera: Scarabaeidae)

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Abstract
The effectiveness of pitfall traps baited with cattle dung enclosed in a gauze bag and pads of cattle dung on soil as methods for sampling dung beetle populations was assessed in the summer-rainfall regions of South Africa using 17 species of nocturnal/crepuscular tunnelling beetles. Pitfall traps accumulated the catch and prevented both access to and emigration from the dung bait. In contrast, beetles had direct access to dung pads on soil which allowed colonists to modify the bait and to emigrate. The number of beetles collected was therefore the net result of immigration and emigration. On each of five occasions in November–December 1985, 40 pitfall traps and 40 dung pads were set out in the evening and the trapped beetles recovered the following morning. Overall, 3774 individuals were trapped. For most species there was no significant difference between trap types in the numbers caught but two species were significantly more numerous in pitfall traps and one species was more numerous in the dung pads. However, both methods produced similar patterns of rank abundance of species (r=0.95). There was no evidence that beetles were more evenly distributed between dung pad baits than between pitfall traps.