The Use of Coverboards in Estimating Patterns of Reptile and Amphibian Biodiversity

Reptiles and amphibians play important roles in ecological communities and can be extremely sensitive indicators of environmental change, despite their cryptic and secretive habits. To estimate herpetofaunal community dynamics potentially attributable to either natural or anthropogenic environmental variation, herpetofaunal biodiversity managers will require specific, standardized, and efficient field sampling methods. One such method involves using arrays of wood and tin coverboards and is the subject of this paper. Studies were conducted on the Savannah River Site in the Upper Coastal Plain of South Carolina from January 1988 to August 1991. Compared with a drift fence/pitfall trap array, the coverboard technique requires less maintenance and sampling effort, but only those reptiles and amphibians using the coverboards at the time of an array check could be encountered. In contrast, live-trapping methods integrate over a longer time period and thereby generate many more encounters per trap. Nonetheless, large numbers of encounters with cryptic reptiles and amphibians can result from coverboard sampling depending upon the study site, coverboard age, time of day, and type of coverboard (i.e., wood or tin). Detailed analyses of hydric and thermal microclimates beneath coverboards suggest specific mechanisms to explain observed differences in herpetofaunal coverboard use. We conclude that the coverboard technique can provide a useful means to quantify patterns in herpetofaunal relative abundance and biodiversity. However, array design and sampling protocol should be carefully selected to minimize sampling biases in encounter probabilities due to subtle differences among herpetofauna in their hygrothermal microclimate preferences.