American Bison | Pronghorn | Black-footed Ferret

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1. American Bison
2. Pronghorn
3. Black-footed Ferret
Credits and Links

American Bison

Great herds of bison once roamed the the North American plains between the Appalachian Mountains on the east and the Rockies on the west. It is estimated that around 30 million of the continent’s largest land animal roamed the region when European settlers first arrived. Herds of bison so large that it appeared there were endless resources of these huge, grazing creatures.

In the 1800’s, the Westward Expansion began across America permanently changing the North American plains. With settlers moving west came farming and plowing, domesticated cattle, the construction of the Transcontinental Railroad and guns.

By the late 1800’s, the American bison had nearly gone extinct. A purposeful effort to clear the land of these giants had begun – for their hides which Germany had perfected the process of turning into fine leather, the skulls were used for fertilizer across the ever-growing number of farms, to make way for domesticated cattle grazing, and because the local Native American tribes relied heavily on the bison for their livelihood – it was a way to drive out and conquer these indigenous people by denying them of this vital resource.

It was estimated fewer than 1,000 bison remained on the American plains by the end of the 1800’s. But the story of the bison did not end there. Due to the efforts of a few conservationists like William Temple Hornaday of the Smithsonian Institute, zoos such a New York’s Bronx Zoo, and the establishment of wildlife preserves – including the first national preserve for bison founded in Oklahoma in 1907 – bison were saved from extinction.

Bison can stand up to 6 feet tall from hoof to shoulder and weigh up to 2000 pounds – they are the largest native terrestrial animal in the Western Hemisphere. They have dark brown shaggy hair with a coarse water-resistant guard hair overcoat and a thick under fur so effective at insulating the animal that snow often won’t melt on their backs. The front of their head is covered in a shaggy mane and beard, even on females.

American bison are ungulates means “being hoofed” or “hoofed mammal.” Other wildlife ungulates include zebra, gazelle, and giraffe. Bison are grazers, they feed primarily on grasses and possess a ruminant digestive system with a four-chambered stomach. Like cows, they eat grass, regurgitate it then re-chew it (known as “chewing the cud.”) Adult bison consume more than 30 pounds of grass in a day.

They are true nomads, roaming an average of 2 miles daily while grazing. Bison once traveled as far as 200 miles in a season. Female bison and calves roam together in larger herds while bulls tend to roam either alone or with just a few other males. Herds interact by grunting and a bull’s bellow can be heard up to 3 miles away.

Despite their large size, bison are quite agile. They can run a speed of up to 35 mph, leap vertically up to 6 feet and they are powerful swimmers – able to cross rivers at least half a mile wide.

When fighting, males will run towards each other and clash heads. Strong head-to-head impacts are made less damaging to the brain by a system of bone struts which divide the inner and outer walls of the skull as well as thick matting of hair that acts as a cushion.

Their notable shoulder hump is primarily muscle, which allows them to use their heads to plow through snow during winter seasons.

Bison often display a behavior called “wallowing” where they will roll on the ground, usually in dry, dusty grassy areas. They wallow as a way to dust themselves in order to keep insects away. It also assists in removing old fur during the spring molt. Urinating in wallows is used by bulls for scent-marking. The depressions left in the soil often collect rainwater and serve as watering holes for smaller animals.

During the summer mating season, known as rut – bulls reunite with herds of cows. Multiple herds will often come together forming large, impressive gatherings. After mating, gestation lasts 285 days and calves will nurse 7 to 9 months, becoming independent at around 1 year of age. Both sexes become sexually mature between 2 and 4 years of age. Physical maturity is reached at 3 years old for females and 6 years old for males.

The are two species of bison, the European and American bison. Both are very similar genetically as well as appearance and size. The American bison contains two subspecies – the Wood bison of the northern range and the Plains bison in the south.

Bison are often mistakenly been referred to as buffalo. However, buffalo are bovines native to Africa and Southeast Asia. Bison possess their signature hump, large head and smaller horns. Buffalo resemble domestic cattle in build, have longer more curved horns and lack the thick fur and beard of a bison.

The American bison was declared the national mammal of the United States in 2016 (the state of Oklahoma named bison the state mammal in 1972) – the first Saturday in November is designated as National Bison Day.

Due to the efforts of many zoological facilities, national parks, preserves and private ranches, bison has returned from the edge of extinction. American Indian nations also have a leading role in the recovery of American bison. Some tribes own land on which bison are protected, and members of those nations help to manage the herds. Through these collaborative efforts, bison herds are once again becoming a fixture on the American landscape.


The second fastest land animal in the world is found exclusively in North America. This deer-like animal has a tan body with a white belly, throat and rump patches. Standing 3 feet at the shoulder and weighing up to 150 pounds, the pronghorn is an American original.

Pronghorn are sometimes referred to as American Antelope however despite their similar appearance – the pronghorn are not related to the antelope common to Africa but comprise their own species and genus classification. There are 5 subspecies of pronghorn, but typically three are recognized as unique.

Their common name is derived from the front facing prongs found on their horns. These “horns” of the pronghorn help make it unique: they are a cross between horns and antlers, with qualities of both.

True antlers are made of bone and shed each year while true horns are made of keratin that grows from a bony core and are never shed. The horns adorning the pronghorn are neither true horns nor true antlers. Instead, the sheath is made of keratin but the horns shed yearly.

Pronghorn are the only animals in the world that have forked horns that shed each year. Both male and females possess horns, males may grow up to 20 inches long while the females are typically much smaller and sometimes underdeveloped.

Pronghorn are found in open prairie and desert habitats in western North America. They spend most of their time eating and resting with their herd. As ruminants with a four-chambered stomach they chew their cud while at rest. Easily startled or distracted, pronghorn rarely sleep for more than 10 minutes at a time.

Pronghorn have large eyes, which give them the ability to see long distances. They also possess enlarged hearts and lungs which give them the ability to process large amounts of oxygen, this ability aids them in generating the energy needed to reach their high running speeds.

The second fastest land animal in the world, the pronghorn can reach speeds up to 60 mph (nearly as fast as the cheetah) and in fact the pronghorn can maintain very high speeds for extended periods of time. They have been known to maintain speeds near 35 mph for several miles. Despite their quick speeds, pronghorns do not have the ability to jump thought they have been known to crawl under barriers such as fences.

The pronghorn’s body hairs are hollow and lie flat to help insulate against the cold winter weather or can be lifted to let air circulate and help cool them during the hotter summer months on the open plains – pronghorns typically avoid areas with trees.

Their diet consists mainly of non-woody flowering plants, known as forbs as well as grasses, cacti and brush. Pronghorn are one of the few large herbivores that can eat sagebrush. They will drink water when available but can go several weeks without a steady water source, acquiring most of their moisture from the plants they consume.

Though found in smaller groups during the summer, pronghorn are usually found in large herds of up to 1,000 animals in the winter months. During the breeding season in September and October a single male will gather several females into a harem. Rival males will often fight using their large horns and the more dominant males will have the better territories for food which may entice other females to join him.

It is common for females to give birth to twins in the spring after an 8 months gestation period. Newborn pronghorn are able to outrun humans at 4 days old and within a week can outrun a horse. Typically the mother keeps the young hidden from predators among the taller prairie grass.

Early pioneers of the the American West claimed that pronghorn were seen as far as the eye could see, with numbers rivaling – perhaps exceeding – that of the much larger American Bison.

They provided food and hides for Native Americans for many years and as settlers moved across America the pronghorns (like the bison) were over-hunted for meat. In addition, they lost their habitat and food sources to the encroaching human population and by the early 1920’s there were reported to be as few as 13,000 animals left.

Today many pronghorn populations have recovered due to efforts of conservationists, zoological facilities and federal laws that protect them. However one subspecies – known as the peninsular pronghorn is at critical risk. Only 150 peninsular pronghorn remain in Baja California, Mexico. Illegal hunting, cattle ranching (along with livestock fences) and habitat loss have led to the rapid decline of this subspecies.

Currently the Los Angeles Zoo is home to an assurance herd of pronghorn. These animals are maintained and bred in case a natural disaster or disease wipes out the herds in the wild.

Black-footed Ferret

Though they were once found in the thousands across the western plains of the United States, today the black-footed ferret is one of North America’s most endangered species. In fact, North America’s only native ferret species was believed to be extinct until a very small population was discovered in 1981.

The remaining 18 animals were captured in the mid-80s to establish a breeding center in Wyoming. In 1988, the National Zoo in Washington D.C. was the first to receive offspring from those 18 and breed black-footed ferrets outside of Wyoming – thus began another comeback story from the American West.

Black-footed ferrets will eat squirrels, mice, and other rodents, however prairie dogs are essential to their survival, making up the majority of their diet. The ferrets will hunt the prairie dogs in their own burrows, and take shelter in abandoned prairie dog dwellings.

As pioneers began to settle the American plains during the Westward expansion, prairie dog populations underwent a huge decline. Farmers and ranchers (with government assistance) eliminated many prairie dogs because their underground complexes were destructive to fields and sometimes dangerous to cattle. In the process, the black-footed ferret was nearly wiped out.

Not the be mistaken with the domestic ferrets commonly seen in pet stores which are descendants of the European polecat, North America’s exclusive black-footed ferret is slightly smaller with yellowish brown or buff colored fur, lighter underparts and black markings on it’s legs, tail tip and mask-like markings around the eyes. They weigh between 1 and half to 2 and half pounds and measure up to 2 feet long.

Ferrets are members of Mustelidae – the largest family in the order Carnivora. This family also includes animals like weasels, minks, martens, otters, badgers and wolverines.

Black-footed ferrets are nocturnal and are solitary except during breeding. They usually only spend a few minutes each day above ground to move to new burrows, hunt or find a mate. But most of their time is spent in prairie dog burrows. They sleep, hunt, eat, give birth and escape from predators or harsh weather conditions in burrows. Young ferrets are quite playful, and can sometimes be seen “dancing” above ground.

Black-footed ferrets, like other mustelids, have a high metabolism and require a relatively large amount of food. A ferret may eat one prairie dog every three days and may eat up to 100 prairie dogs a year. They’ll also eat other rodents, rabbits as well as birds, reptiles and insects.

In the 1970’s, an effort to conserve the ferrets ended in heartbreak as captive breeding efforts were unsuccessful and the black-footed ferret was feared to be lost.

Remarkably, in 1981 in Meeteetse (ma-teet-see) Wyoming, a ranch dog named Shep brought home a small animal that was identified as a black-footed ferret. Biologist discovered small colonies of black-footed ferrets after surveying the area. By observing and studying the ferrets, they gained vital information for the management and husbandry of these highly endangered mammals.

The US Fish and Wildlife Service in partnership with several AZA-accredited facilities including the Smithsonian’s National Zoo Conservation Biology Institute works to reintroduce the ferrets into their native habitats. This involves a process called “preconditioning” which helps familiarize the animals with underground tunnels and hunting techniques to increase the chance that they will survive in the wild.

The biggest threat to black-footed ferrets is lack of suitable habitat and the continued decline of the prairie dog, their main prey. Diseases such as canine distemper and sylvatic plaque (which is spread by fleas) also pose major threats to their ongoing survival.

Dan Ashe, President and CEO of the Association of Zoos and Aquariums says “The black-footed ferret is an iconic conservation story, used to train and inspire the next generation of wildlife biologists [and] there is always cause for hope, even in the face of the daunting challenges that our planet faces.”


Special thanks to the following organizations for their education, research and conservation programs that provided information for this episode:

Black-footed Ferret Connection
Bronx Zoo
Columbus Zoo & Aquarium
Elmwood Park Zoo
Minnesota Zoo
National Park Services – Yellowstone
National Park Services – Bison Bellows blog series
The Nature Conservancy
Oklahoma City Zoo
Phoenix Zoo
San Diego Zoo
Smithsonian’s National Zoo

For original wildlife artwork and more amazing animal facts visit: