Counting The Herd
The biologists captured, marked and released 69 deer between Dec. 2, 1996, and Jan. 10, 1997. During a series of two-a-day flights the week of Jan. 11-17, 1997, biologists were able to count and compare the numbers of uncollared deer with the control count of collared deer to make a scientific estimate of the entire wild herd.
The census was performed with two experienced observers and a pilot in a Bell Jet Ranger helicopter traveling roughly 25 miles per hour some 200 feet above the ground, depending on conditions and terrain. The observers covered 65-yard transect plots indicated by bright-colored, numbered plywood squares fastened to the perimeter fence around Tyson. The flights were conducted one to two hours after sunrise and two to three hours before sundown. Flights were repeated 10 times over several days at the same time to lessen the possibility of a counting error.
"One of the key things is that we had a known population to start with," says Beringer. "That's a definite asset to any census. There have been many other attempts without a known population; then a pre-count assumption has to be made. But the GPS keeping us on our transect plots was the most important added feature to our study."
Excessive deer pose several problems for research at the Tyson Research Center, which is enclosed on all its borders by 8-foot fencing that is considered deer-proof. Deer face an inadequate food supply when they are overcrowded, which means that their health is affected and that fawns reach maturity at a much slower rate.
Too many deer accelerate the incidence of ticks, which coexist with deer. Some ticks carry Lyme Disease, which is a hazard to researchers, visitors and participants in field activities at Tyson and possibly to surrounding wildlife areas.
Too many deer also conflict with the goal of Tyson, which is to be a research
center representative of pre-
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Contact: Tony Fitzpatrick
p72245tf@wuvmd.wustl.edu
(314) 935-5272
Washington University in St. Louis
2-Jul-1998