A place called the eradication zone, lying about 40 miles west of Madison, Wis., covers some 411 square miles. There thousands of white-tailed deer live--or rather, used to live. Last year the Wisconsin Department of Natural Resources instituted special hunting periods to try to wipe out upward of 18,000 deer. During the fall, dead deer were taken to registration areas, where state employees in protective suits and gloves dragged carcasses from pickup trucks and lifted them onto plastic-covered picnic tables. With hacksaws, they severed the heads, double-bagged them and sent them for testing; the bodies themselves were incinerated. The Dairy...