Terrestrial Drift Fences With Pitfall Traps: 



An Effective Technique for Quantitative 



Sampling of Animal Populations 



J. Whitfield Gibbons and Raymond D. Semlitsch 



Savannah River Ecology Laboratory, 



Drawer E, Aiken, South Carolina 29801 



ABSTRACT. — The terrestrial drift fence with pitfall traps is a com- 

 monly used technique to collect and quantitatively sample populations 

 of certain vertebrate and invertebrate species. However, a variety of 

 limitations, advantages, biases, and contingencies must be considered 

 to use the method most effectively. The best materials to use for these 

 fences and traps have been aluminum flashing and plastic 20-liter 

 buckets. Aluminum flashing is rigid and does not deteriorate with age. 

 Large plastic buckets permit the capture of many species that can 

 escape from small can traps. Maintenance, such as filling cracks or 

 holes along the fence, bailing water from traps, and mowing vegetation 

 alongside fences, are necessary for continued effectiveness. Initial cost 

 of construction is high, both in time and money; however, drift fences 

 are cost effective for most ecological studies. Biases result primarily 

 from variation in morphology, ecology, and behavior of species, or as 

 a consequence of design and the manner in which the drift fence is 

 checked and maintained. 



INTRODUCTION 



The terrestrial drift fence and pitfall trap technique has been used 

 for many years for field sampling a variety of vertebrate and inverte- 

 brate species (e.g. Imler 1945; Gloyd 1947; Woodbury 195 1, 1953; 

 Storm and Pimentel 1954; Packer 1960; Husting 1965; Shoop 1968; 

 Hurlbert 1969; Gibbons 1970; Gibbons and Bennett 1974; Briese and 

 Smith 1974; Randolph et al. 1976; Collins and Wilbur 1979; Bennett et 

 al. 1980; Brown 1981; Wygoda 1981). The use of pitfall traps (without 

 drift fences) in the study of invertebrates was reviewed by Mitchell 

 (1963) and Greenslade (1964); however, no thorough assessment of the 

 drift fence technique has been presented (but see Storm and Pimentel 

 1954). Our purpose is to discuss the advantages as well as the limitations 

 of the approach, using examples from 13 years of data taken on reptiles 

 and amphibians collected on the U. S. Department of Energy's Savan- 

 nah River Plant (SRP) near Aiken, South Carolina. 



CONSTRUCTION OF DRIFT FENCES 



Basic design for a terrestrial drift fence is a straight fence extending 

 slightly below ground and up to 50 cm high, with pitfall traps placed 



Brimleyana No. 7:1-16. July 1981. 1 



