Influence of Pitfall and Drift Fence Design on Capture Rates of Small Vertebrates in Semi-Arid Habitats of Western-Australia

Abstract

The influence of several attributes of pitfall and drift fence design on capture rates of small vertebrates was examined over 12 months in semi-arid habitats of Western Australia. Large 28 cm diameter pits (20 L buckets), captured significantly more animals than smaller pits made of 16 cm diameter PVC piping. Amongst taxonomic groups, large lizards and geckos showed highly significant biases for large pits, frogs, small lizards, and snakes and legless lizards less so, while small mammals were caught equally often in both sizes. All faunal groups except geckos showed an overall significant increase in capture rates with increasing fence length, but the optimal length per pit cannot be accurately determined from our data. Faunal groups showed a dichotomy in responses to temporary verus permanent drift fences. Independent fenced pits produced significantly higher capture rates than those in a conventional driftline. Variations in species responses to different design attributes probably reflect differing modes of behaviour and activity. We conclude that for our study areas, many large pits installed as a grid at 10-20 m spacing, each with a permanently erected short drift fence (e.g. 7-10 m), should produce excellent results for both autecological and synecological studies.