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Female bison are getting ready to have calves!

Wednesday, April 1, 2026

Once a heifer becomes pregnant, the gestation period is not always predictable. This is due to the fact that a mother bison can actually delay birthing, depending on her physical condition and stress level. Several factors can dictate when a calf is born. For example, storms and changes in atmospheric pressure can affect the timing of the birth; the calf might be born before a storm, or its birth may be delayed until afterward. In general, the gestation period for bison is nine and one-half months.

Usually calves are born from April to June but we have had calves as early as March and as late as July before this calf was born.

Bison calves are often called “cinnamons” due to their coloring when they are young.