The Pitfalls of Pitfall Traps

Abstract

The effectiveness of pitfall versus funnel traps was examined using drift fence data from five studies that employed different array designs, fencing materials, and numbers of traps in diverse Florida habitats. In general, salamanders, anurans, lizards, and snakes were captured more frequently than expected in funnel traps than in pitfall traps. In most studies, hylid frogs (Hyla, Acris, and Pseudacris) were captured significantly more often in funnel traps, but other anuran groups were captured either more often in funnel traps or equally as often in both types of traps. Most lizards and medium-sized and large snake species were captured more often in funnel traps, but semifossorial lizard (i.e, Eumeces egregius) and snake (e.g, Tantilla relicta) species were usually captured in pitfall traps. Too few turtle and small snake species were trapped to draw conclusions. Other studies that found funnel traps to be less effective than pitfall traps for some herpetofauna used funnel traps that were smaller or that might have been poorly constructed or installed. Reptiles had similar mortality rates in both types of traps, but in drier habitats, anurans were more prone to dying in funnel than in pitfall traps, despite the presence of shade covers and sponges. Overall herpetofaunal mortality rates were higher in funnel traps than pitfall traps, but this difference was significant only for the study with the longest interval between checking traps in terrestrial habitats. Traps should be checked at least every three days to minimize mortality. In the Coastal Plain of the southeastern United States, most species can be effectively sampled by using only funnel traps, but pitfall traps should be added in xeric upland habitats to increase the chance of capturing semifossorial or fossorial reptiles. In the Coastal Plain of the southeastern Unit-