A large bull Moose (Alces americanus) jumps over a buck n’ rail fence chasing after a female moose during the fall rut. Grand Teton National Park, Wyoming

A large bull elk (Cervus canadensis) in velvet emerges through the trees, stops momentarily investigating the scene. Banff National Park, Alberta, Canada

A portrait head shot of a large bull elk (Cervus canadensis), standing close by keeping a watchful eye on his harem during the fall rut. Yellowstone National Park, Wyoming

A stately bull elk (Cervus canadensis), proudly displaying his heavily wooded rack stands patiently, waiting to move his harem during the fall rut. Grand Teton National Park, Wyoming

A large woodland caribou (Rangifer tarandus) bull, sporting his massive rack of velvet stands munching on young tender shrubs. Gros Morne National Park, Newfoundland, Canada.

A young white-tailed deer (Odocoileus virginianus), peeking its head through the russet colored grasses at sunrise. The Great Smoky Mountains National Park, Tennessee.

A stately bull elk (Cervus canadensis), proudly displaying his immense antlers standing among sage brush and evergreen trees keeping a watchful eye on his harem during the fall rut. Grand Teton National Park, Wyoming

Elk (Cervus canadensis) breed in harems that are closely guarded by harem bulls against rivals, as well as escaping cows. This bull is chasing another bull to defend his harem from an intruder. Yellowstone National Park, Wyoming

This cow moose (Alces alces) and her calf are alert and aware of our presence. Both are standing with their ears up and forward and appear to be smiling. Don’t be fooled, a cow moose with her calf is a very dangerous

An alert moose (Alices alces) calf with its mother nearby is busy nibbling on leaves and berries bulking up before winter, when food is in short supply. Grand Teton National Park, Wyoming

A nine point white-tailed deer (Odocoileus virginianus) standing in the tall russet grasses at sunrise on a cold foggy morning during the fall rut. The Great Smoky Mountains National Park, Tennessee

A dominant bull elk (Cervus canadensis), proudly displaying his massive rack standing among sage brush and evergreen trees keeping a watchful eye on his harem during the fall rut. Grand Teton National Park, Wyoming

An impressive bull elk (Cervus canadensis) proudly displaying his heavily wooded rack, as he stands among the sage brush and evergreen trees guarding his harem during the fall rut. Grand Teton National Park, Wyoming

A sizable bull moose (Alces alces) appears to be on a mission. Sporting his shiny dark coat and massive antlers, he heads off to look for a mate as mature tells him it is time to reproduce. Grand Teton National Park, Wyoming

A close up of a huge bull Moose (Alces americanus) seen grunting in an attempt to lure a mate during the rutting season in the boreal forest of the northern peninsula. Newfoundland, Canada

Elk (Cervus canadensis) breed in harems that are closely guarded by harem bulls against rivals, as well as escaping cows. This bull is crossing a river to defend his harem from an intruder. Yellowstone National Park, Wyoming

Elk (Cervus Canadensis) breed in harems, which are closely guarded by harem bulls against rivals, as well as escaping cows. This bull is crossing the Madison River to defend his harem from an intruder. Yellowstone National Park, Wyoming

This young bull Moose (Alces alces) is busy drinking and eating the aquatics necessary to obtain the sodium required to maintain growth and reproduction of antlers. Grand Teton National Park, Wyoming