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Bison Calves Born at Brookfield Zoo

The Chicago Zoological Society, which manages Brookfield Zoo, is happy to announce the recent births of two bison calves: a male calf born to Leotie, 5, on May 31 and a female born to Lucy, 5, on June 6. Ron, 14, is the sire of both calves. For a few weeks beginning June 16, guests can see the calves and the rest of the herd on Saturdays and Sundays only while their outdoor habitat at Great Bear Wilderness undergoes routine maintenance. Once the project is complete, the entire herd will be viewable on exhibit daily. The public can check the zoo’s website at www.CZS.org for updates on the renovation completion date.

The male is Leotie’s second calf. In 2012, she gave birth to a female named Hope, who still resides at the zoo. Prior to Hope’s birth, there had not been any calves of this species born at Brookfield Zoo since the early 1970s. The seventh member of the bison herd is Judy, 14.

Bison are the symbol of the Chicago Zoological Society because they are one of the first North American conservation success stories. The species was slaughtered to near extinction in the late 1800s, when they were hunted for their meat and bones but primarily for their hides, which were made into clothing, machine belts, and rugs. Historically, tens of millions of bison traveled hundreds of miles over the same route through the Great Plains, shaping the land and enriching the soil. Remnants of their deeply worn paths are still visible. However, by the end of the 19th century, bison populations were eliminated over 98 percent of their range in the lower 48 states, resulting in fewer than 1,000 individuals remaining.

Today, bison are making a comeback. Approximately 500,000 are managed on ranches and tribal lands, and about 20,000 live in protected parks and preserves such as Yellowstone National Park. Additionally, one of the Society’s conservation partners, American Prairie Foundation, a nonprofit organization founded in 2001, is working with government and other conservation organizations to increase bison populations by protecting the animals and their habitat. The organization is purchasing private land that borders public land so that bison may roam freely once again. In partnership with the World Wildlife Fund, American Prairie Foundation is assembling a multimillion-acre wildlife reserve to protect the species-rich grassland of northeastern Montana, where bison and other wildlife can thrive.

Some refer to bison as buffalo, which is theoretically inaccurate. True buffalo are native only to Asia and Africa. A member of the bovine family, bison are the largest land animal in North America. Males, called bulls, can stand 6 to 6.5 feet tall and weigh up to 2,000 pounds; females, or cows, are slightly shorter and can weigh between 800 and 1,000 pounds. The calves weigh approximately 40 to 50 pounds at birth. Bison have a broad forehead and large head; short, curved horns; and a pronounced shoulder hump. They have a dark brown shaggy coat on their front legs, neck, and shoulders and shorter hair on the rest of the body. Their thick mane and coat protect them from severe winter weather; snow can cover their back without melting because they are so well insulated. The coat changes to a lighter color in spring, and as the weather warms, they shed their winter coat, which is replaced with new hair in late spring.

Bison calves are born with a reddish coat at birth, and over a period of about 15 weeks it darkens to dark brown. They are able to stand within half an hour of their birth and can run after a few hours. Calves begin grazing when they are just shy of a week old but continue to nurse for several months.