MADISON – Department of Natural Resources biologists will conduct an aerial deer population count in the chronic wasting disease (CWD) Disease Eradication Zones (DEZ) beginning the week of February 20, weather permitting.

Agency biologists will use a helicopter to determine the number of deer in the 1,280 square mile western DEZ encompassing much of Iowa County, western Dane County, southern Sauk County plus small sections of Columbia, Green, Lafayette and Richland Counties, and the 462 square mile eastern DEZ covering southeast Rock County, almost half of Walworth County, and a small section of Racine County.

It is possible that once the smaller eastern area is covered people may see two helicopters working simultaneously in the western area. Data gathered are used to estimate the success of landowner and hunter efforts at reducing herd populations in the area where the disease is known to exist. Landowners are making steady progress in this effort, say biologists, with populations in some of the diseased areas having been reduced by roughly one-third.

Biologists estimate the survey will take at least three weeks, but “everything is dependent on having at least three to four inches, preferably six to 12 inches, of snow on the ground to cover logs and stumps so deer are clearly visible on the landscape,” noted agency wildlife population ecologist Robert Rolley.

DNR frequently uses aircraft for wildlife population surveys, such as counting bald eagles and trumpeter swan nests, and tracking wolves. Pilots generally fly high enough to avoid spooking animals, since that only makes counting more difficult when deer are moving about.