2 Bison Calves Born At Fermilab

BATAVIA, IL — Fermilab welcomed two bison calves Monday, signaling the start of spring at the particle physics laboratory in Batavia.

The calves were born "healthy and strong," joining the herd that has been part of the lab since 1969, officials said.

Cleo Garcia, Fermilab's herdsman, estimates about 20 calves will be born this season. Calving season continues through June, although last year, one was born in September.

"Our herd is doing well," Garcia said in a statement. "Each year, we monitor the cows closely to estimate how many calves we'll have. It’s always exciting to see the first birth of the season."

The herd currently consists of 23 cows, two bulls and three yearlings born in 2024. Fermilab rotates its bulls every five years to maintain genetic diversity, which ensures the animals remain close to 100 percent pure American bison, officials said.

"Genetic testing in 2015 confirmed that the herd contains little to no cattle genes — a significant achievement," Fermilab officials wrote in a news release.

When calves are born, they wear a cinnamon-colored coat, which darkens to brown as they grow. They weigh between 40 to 70 pounds at birth, and by six months, they can reach 300 to 350 pounds.

"One of the most exciting moments is when a calf takes its first steps," Garcia said. "Sometimes, within just a few minutes of being born, they’re already up and walking around — it’s incredible to see."

Visitors are encouraged to visit the Fermilab grounds to see the herd and its newest members. The outdoor public areas are open daily from dawn to dusk.