YELLOWSTONE NATIONAL PARK, Wyo. (AP) -- Elk and other wildlife in Yellowstone National Park are beginning to leave the high country for lower elevations as they do every fall.

The most obvious change in Yellowstone occurs in Mammoth Hot Springs.

Typically, several large bull elk venture into the Mammoth area in the fall to compete for the attention of cow elk.

Bulls are much more aggressive toward both people and vehicles this time of year and can be a threat to both people and property. Several vehicles are damaged by elk every year, and on occasion people are charged by elk and are injured.

Park regulations require visitors to stay a minimum of 25 yards away from most large animals and at least 100 yards away from bears.