SAMPLING CARABID ASSEMBLAGES WITH PITFALL TRAPS: THE MADNESS AND THE METHOD

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Abstract
We describe a litter-washing technique for collecting quantitative samples of ground-beetles (Carabidae), and compare the results with those from liner extraction by Tullgren funnels and pitfall (rapping. We also compare performance of four types of pitfall traps across five habitats. Carabid species composition from litter washing and funnel extraction was similar but washing revealed higher densities. Large-bodied species predominated in pitfall samples and small-bodied species predominated in litter samples. Uncovered, round pitfall traps yielded generally higher catches than rectangular or covered, round traps but the pattern was not consistent over all species or the five habitats. Ecological studies of carabid populations and assemblages using pitfall traps may be improved if they are both designed and interpreted in light of the biology of the group and with regard to the deficiencies of pitfall trapping as discussed here and elsewhere.