Bison are a conservation success story – and the national mammal

In May, the American bison was named the national mammal of the United States. These bearded, brown-eyed bovine are iconic symbols of the American West.

Ruggedly handsome

The American bison is large. Very large. Actually, it’s the largest land mammal native to North America. Males can grow to weigh more than 1 ton and can be up to 6 feet tall at the shoulder, with horns up to 2 feet long. Bison also are quite strong, with the ability to run 30 mph when startled.

Bison have remarkably thick fur coats that protect them from the elements. A bison’s coat changes color as it grows, starting as burnt orange at birth and turning chocolate brown over a few months.

These massive mammals are built to tolerate cold weather. Fur provides insulation similar to a puffy winter jacket: Snow can fall on a bison’s back without melting. Bison also use their massive heads to push snow aside in winter months when searching for grasses to eat.

In spring, the outer layer of fur is shed, giving bison a shaggy and unkempt appearance.

Herd life

American bison herds are separated into male and female groups for most of the year, although young male calves stay with their mothers. Bison roll around in dirt, eat grasses and other vegetation, and communicate through grunts, growls and snorts. Male bison are known as bulls, while females are cows.

Bison are ruminants, meaning they have multiple stomach chambers that help them break down large amounts of plant food. Like dairy cattle, they chew their food, digest it for a while in the stomach, then chew it some more. This is known as “chewing their cud.” Bacteria in the stomach helps convert plant molecules into more easily digestible compounds.

During the bison “rut,” or breeding season, bulls approach the female group in search of mates. Head butting, shoving and locking horns are some of the ways bulls intimidate each other and advertise their strength to cows. After asserting dominance, bulls attempt to isolate their respective partners from the rest of the herd, although cows can walk away if they aren’t interested.

Hormonal attraction is key during mating season, which is why bulls roll around in urine-soaked mud. To a bison cow, that smells like the finest cologne.

The bison rut from August to September.

Home on the range

Millions of these majestic animals once roamed North America. Bison were significant to the culture and economy of Native Americans, who hunted them sustainably. Herds remained plentiful throughout the Great Plains until settlers wiped out most of the population in the late 1800s, leaving just a few hundred behind.

Thanks to conservation efforts, bison numbers have started to increase again. There currently are about 500,000 bison in North America, mostly living in national parks and refuges, as well as some state parks. Breeding management programs and the protection of public lands, especially Yellowstone National Park, have saved this species from the verge of extinction.

This story was originally published September 10, 2016 at 5:37 AM with the headline "Bison are a conservation success story – and the national mammal."