Electronically tracking animals no easy task
Jerry Davis
For the State Journal
Animals can carry radios on a collar (deer), a harness (turkey) or one can be imbedded under the skin (rattlesnake).
Now, imagine if researchers could simply call animals on a cellular telephone and ask, “where are you?”
If only it were that simple.
A VHF radio sends signals to a receiver that is hand-carried in a field or transported in an airplane or truck. By taking a number of readings from the radio, a researcher can triangulate where the animal is or simply walk in the direction giving a stronger signal until the animal, such as a rattlesnake, is found.
Species currently being followed by university and Department of Natural Resources researchers include blue-winged teal, bullsnakes, deer, elk, fish, prairie chickens, rattlesnakes, ruffed grouse, spruce grouse and wolves.
The devices can collect and/or send out information in a number of ways and at predetermined intervals. For example, the radio send constant signals. GPS radios will record the animal’s location at set intervals — but then the GPS unit must be retrieved from the animal or programed to drop off the collar. A researcher can then use the signal to find the dropped unit and get the information.
“The state-of-the-art systems, which cost in excess of $2,500, can transmit information back to the satellite and the information can then be downloaded by someone in an office,” said Nancy Mathews, Professor and Chair of Conservation Biology and Sustainable Development in the Gaylord Nelson Institute for Environmental Studies at the University of Wisconsin.
Mathews conducted a six-year study on white-tailed deer in Iowa and Dane counties to determine deer ranges and dispersal patterns, among other things. At one time she and her students and assistants were tracking up to 150 deer.
“Some of the best information we obtained dealt with dispersal patterns and exploratory movements,” Mathews said. “There’s much more we could learn, but the funding for the project ran out and we’re no longer following the few deer that still have collars.”
Most of the collars Mathews purchased cost about $250, and simply sent a signal back to a radio antenna held by a researcher who then plotted the animal’s location. During the study, 33,340 telemetry locations were plotted.
“We also dispelled several myths about deer in this area,” she said.
“No adult males studied dispersed from the study area. Deer that were disturbed during the nine-day gun deer season (2005) moved away some but came back to their home ranges within 24 hours.”
Radios have a determined battery life, which was about three years for those Mathews used, but some lasted five years.
A radio in a timber rattler in Sauk County went bad soon after it was implanted.
Elk have been equipped with radio collars since they were re-introduced in 1995. New calves are caught and collared each spring. Mature elk are recaptured to replace collars.
“We have about 138 wild elk in Wisconsin right now and about 77 of those have radio collars,” said Laine Stowell, DNR wildlife biologist in Hayward. “Some radios are equipped to trigger flashing lights along Highway 77 near Clam Lake when the elk come close to the highway.”
Many of the wolves in the overlapping areas also are being studied using radios.
“We had installed 12 GPS radios on elk for a university project,” Stowell said. “The units were programed to have an explosive release, but only two worked, so we recaptured the elk to get the GPS information from the collars.”
Data from the elk radios have helped Stowell determine the specific kinds of habitat the animals use — and when they use it.
“Basically elk are homebodies in the Clam Lake area,” he said.
Stowell has had to deal with other concerns, such as calves growing and the enlargement of bulls’ necks during the rut.
Researchers must obtain state and DNR clearance to conduct research, according to Mathews.
“This is a 2-3 month process to make sure all the federal and state guidelines will be followed and the animals won’t be stressed,” she said.