The Drift Fence at Davidson College

BACKGROUND INFORMATION
Drift fences are often used to collect, survey, and monitor amphibians and reptiles.  Students at Davidson College have used drift fences to gain a better understanding of the reptiles and amphibians present in the area. During the spring of 1999, students at Davidson College constructed a series of drift fences (about 1000 feet in all) in the forest in the northern part of what is now the Davidson College Ecological Preserve. These fences are usually opened (trapping animals) during the Spring and Fall of each year. When opened, they are run daily by students working in the Herpetology Laboratory.

 

HOW DOES A DRIFT FENCE WORK?
A drift fence is essentially a wall that most reptiles and amphibians cannot jump or climb over.  The "wall" is usually a couple feet in height and can be as long as the area you wish to study.  When critters move through the forest, the fence forces them to crawl along it, seeking an opening.  Along the length of the fence, we installed 5-gallon buckets flush with the ground.  As an animal tries to find a way around the fence, it falls into one of the pitfalls from which it cannot escape.  Since many snakes can easily escape from a bucket, funnel traps are also placed along the fence.  The funnel traps allow snakes to enter them.  However, once inside the trap, no exit is readily apparent to them.

 

WHAT HAPPENS NEXT?
Student volunteers check the drift fence on a daily basis to monitor for herps.  Daily monitoring is essential in order to prevent dehydration of captured animals.  In addition, captured amphibians or reptiles are more vulnerable to predation in the bucket so it is important to minimize this problem.  After each amphibian or reptile is marked or recorded, it is released in the direction it was heading before it encountered "the wall."

 

PALM PILOT DATA ENTRY
In the fall of 2001 Mike Dorcas and student J.D. Willson developed a data entry program that allows the drift fence worker to use a Palm Pilot to enter data gathered while running the drift fence. The Palm uses Pendragon Forms 3.1 software to allow a variety of capture and climatic data to be entered into the hand-held computer in the field. The Palm is then synched with the lab computer and all the data is automatically entered in a database. Using this new technology has greatly reduced the amount of equipment that students must bring with them in the field while running the drift fence and eliminates time and and possibility for error associated with manual data entry.

 

LONG TERM STUDIES
Drift fences are fairly permanent structures and allow for long-term, intensive monitoring of reptiles and amphibians.  One drift fence at the Savannah River Ecology Lab in South Carolina has been in operation for more than 20 years!  This particular fence has allowed scientists to better understand these somewhat elusive creatures and their role in the local ecosystem.

  SPECIES CAPTURED IN THE DAVIDSON DRIFT FENCE THUS FAR: (April 2002)

Salamanders
Red Salamander (Pseudotriton ruber
Slimy salamander (Plethodon cylindraceus)
Southern Two-Lined Salamander (Eurycea cirrigera)
Spotted salamander (Ambystoma maculatum)
Toads and Frogs
American Toad (Bufo americanus)
Fowler’s Toad (Bufo woodhousii)
Green Frog (Rana clamitans)
Pickerel Frogs (Rana palustris)
Southern Leopard Frog (Rana utricularia)
Upland Chorus Frog (Pseudacris triseriata)
Bullfrog (Rana catesbieana)
Eastern Narrowmouth Toad (Gastrophryne carolinensis)
Turtles
Eastern Box Turtle (Terrapene carolina)
Lizards
Eastern Fence Lizard (Sceloporus undulatus)
Five-Lined Skink (Eumeces fasciatus
Ground skink (Scincella lateralis)
Southeastern Five-Lined Skink (Eumeces inexpectatus)
Snakes
Black Rat Snake (Elaphe obsoleta)
Black Racer (Coluber constrictor)
Northern Water Snake (Nerodia sipedon)
Rough Green Snake (Ophaedrys aestivus)
Brown Snake (Storeria dekayi)
Copperhead (Agkistrodon contortrix)
Eastern Worm Snake (Carphophis amoenus)
Ringneck Snake (Diadophis punctatus)
Redbelly Snake (Storeria occipitomaculata)

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Photo credits: Kelly Kiefer and Aaron Rice and J.D. Willson