A bull Elk on a frosty Madison river. Yellowstone National Park.

A young buck Elk on a frosty Madison river. Yellowstone National Park.

A bull Elk bugling during the rut on the Madison river. Yellowstone National Park.

A bull Elk crossing the Madison river. Yellowstone National Park.

A bull Elk crossing the Madison river. Yellowstone National Park.

A bull Elk crossing the Madison river. Yellowstone National Park.

A bull Elk at his favourite tree in the Madison campground. Yellowstone National Park.

A bull Elk at his favourite tree in the Madison campground. Yellowstone National Park.

A bull Elk bugling during the rut on the Madison river. Yellowstone National Park.

A bull Elk bugling during the rut on the Madison river. Yellowstone National Park.

A bull Elk bugling in the Rocky Mountain National Park, Colorado.

A bull Elk bugling in the Rocky Mountain National Park, Colorado.

A bull Elk at his favourite tree in the Rocky Mountain National Park, Colorado.

A bull Elk at his favourite tree in the Rocky Mountain National Park, Colorado.

Bull Elk sparring in the Rocky Mountain National Park, Colorado.

Bull Elk sparring in the Rocky Mountain National Park, Colorado.

A bull Elk bugling in the Rocky Mountain National Park, Colorado.

A bull Elk bugling during the rut on the Madison river. Yellowstone National Park.