Terrestrial Drift Fences with Pitfall Traps 5 



Table 1. Categorization of time, labor, and expenses for materials for various 



stages of drift fence construction, maintenance and operation for two 



study sites on the Savannah River Plant. 



Category 



Sites 

 Rainbow Bay Sun Bay 



September 



1978 



February 1979 



440 





450 



88 





90 



168 





119 



$660 





$682 























$10 





$10 



$80 





$80 



Date constructed 

 Circumference (m of fencing) 

 Number of pitfall traps 

 Construction costs: 



total labor (man hours) 



aluminum flashing (@$22/roll) 



buckets (obtained at no cost) 



stakes (180/ fence obtained at 

 no cost) 



plastic cable ties (400/ fence) 



shovels, axes, sledge hammer 



Maintenance costs (hr/yr): 



cut grass around fence 5 5 



check and fill cracks and holes, 



replace sponges, renumber pitfall 



traps, and other routine 



maintenance 4 4 



Operation (hr/yr): 



daily checking of pitfall traps 



and processing animals (not 



including transportation) 365 365 



with any sampling technique, certain biases and limitations must be 

 taken into account in the interpretation of data. Biases are primarily 

 due to variation in morphology, ecology, and behavior of species, or are 

 a consequence of fence design and the manner in which it is checked 

 and maintained. 



A species' morphology is an obvious factor in determining the 

 effectiveness of the technique in capturing certain animals. The large 

 body size of some snakes and mammals permits ready escape from the 

 pitfall traps, as does an ability to climb or jump over the fence. Climb- 

 ing or burrowing adaptations, such as toepads on treefrogs or the dig- 

 ging limbs of moles, can reduce the proportion of the population that is 

 actually sampled. 



Behavior can also influence the capture of certain species. For 

 example, although many specimens of the eastern box turtle, Terrapene 



