What’s that deer wearing?

The electronic neckwear sported by some deer around Mt. Horeb allows CWD researchers to monitor their movements around the clock. The reusable collar units weigh just over a pound, including the lithium battery that powers them for three years. The transmitter’s signal can be picked up a mile away over level ground, and up to five miles from the air. Using a motion-sensing mercury switch, the collar transmits a mortality signal if the deer doesn’t move for more than four hours.

The collar strap is neoprene-impregnated cotton duck belting, and the electronics are housed in a brown metal canister. Heavy plastic tubing protects the external antenna, because deer like to chew on the antennas while grooming each other.

Researchers adjust the collars to fit snugly but allow room for growth in young deer and Neck expansion as bucks enter the rut. Collars on young deer include a foam shim under the strap that allows expansion and wears away as the deer grows up.

The collars don’t appear to interfere with deer behavior, according to University of Wisconsin–Madison wildlife ecologist Nancy Mathews. Research guidelines require radio collars and other devices to weigh less than 5 percent of an animal’s body weight, and these units are well under that limit.

The collars cost about $250 each, and were paid for by the Wisconsin Department of Natural Resources, the National Cattlemen’s and Beef Association, and Whitetails Unlimited.