TRUCKEE (AP) — Scientists in the Sierra Nevada have started tracking a mule deer herd north of Lake Tahoe with radio collars to try to learn more about their migration patterns and better understand why so many are struck by cars. The California Department of Fish and Wildlife says an average of nearly three dozen deer are killed annually on a busy 25-mile stretch of State Highway 89 between Truckee and Loyalton. More than 1,000 have been killed there since 1988.