Ten bison facts from Don Hanson’s log

1. The log says
First calf of the season was born on April 18, in the morning. The last one born on May 17.
28 baby bison in 30 days. For some of them it’s too soon to tell if they are male or female, they have to be a few weeks old before it shows.

2. Adding it up
3 full grown bulls
30 full grown cows
6 heifers (that’s how a cow is called until it gets its first calf)
1 calf left from October 2000
28 newborn calves

3. What’s for dinner
A mature bison eats 12 to 15 pounds of hay a day. In the summer time they eat grass. They also get 8 pounds of dairy pellets a day.

4. Shedding winter hair
The bison are now starting to shed, losing their winter hair. They are expected to have lost it all in July. But with this weather, that could be running a little late.

5. The weight
A full grown bull weighs over 2000 pounds, a cow between 1200 and 1400 pounds, a little calf between 45 and 50 pounds.

6. A bison nursery
When the cow is ready to calve, it separates from the herd. Even when the calf is born, the cow will wait a day or two to bond with it before it returns to the herd. When more calves are born the mums form a nursery group apart from the still-expecting moms. As soon as a new calf is born, mother and calf are invited into the nursery group, to bison baby talk.

7. When do the babies stop being babies
When the babies are 5 to 6 months, they can be taken away from their mothers. It takes 3 to 4 years, though, to grow mature, 5 to 6 years to get their maximum weight.

8. What happens in the near future
At the Barn they try not to have more than 80 to 90 bison at once. This fall the calves will be auctioned. Mostly breeders, coming from Missouri, Indiana and even Minnesota, will buy them to get new blood lines in their herds.

9. It’s bison, not buffalo
Don has been told once that in the early days European explorers thought the animals looked like Asian buffalos, but they are definitely a species of their own, called bison.

10. What is at the top of Don’s things-to-do-list
First thing to do is getting the fences redone and the hay inside, but with this rainy weather not much gets done at all.

(Don Hanson has worked nearly 25 years at the barn, taking care of the bison and all that needs to be done to have them at Fermilab.)

More about bison at Fermilab