WILMINGTON – Baby bison have arrived at the Midewin National Tallgrass Prairie.

In a Midewin news release issued this week, staff announced five bison calves have been born since Saturday. All appear to be healthy and doing well, according to the news release, and more calves are expected to be born later this spring.

They arrived just in time for the May 7 "Midewin Bison Expedition" – a one-day event during which the prairie's new bison herd can be seen from a closer-than-normal viewing location.

That day, free shuttle buses will be provided every 15 to 20 minutes by the U.S. Forest Service from 9 a.m. to 4 p.m. – bringing folks to and from the neighboring towns of Elwood and Wilmington.

Visitors can be picked up near City Hall in Elwood, 401 E. Mississippi Ave., and at North Water and Van Buren streets in Wilmington.

Buses will return visitors to either location until 5 p.m.

American bison – four bulls and 23 cows – were reintroduced to the prairie's pastures in October. All the female bison were already pregnant at that point. Pregnancy for a female bison lasts about nine and a half months.

Calves are typically able to stand and nurse within 30 minutes of birth, according to the U.S. Forest Service. The baby bison may try to graze within five days and drink water after the first week.

In the wild, few American bison survive more than 20 years, but life span increases if they are in captivity, according to the U.S. Forest Service.

The Midewin National Tallgrass Prairie, which is operated by the U.S. Forest Service, reintroduced the bison last fall as part of an experimental 20-year project to see how the herd’s grazing habits can benefit the area’s tallgrass prairie ecosystem and grassland bird habitat.

The bison range can be accessed via the Iron Bridge Trailhead on Route 53 at the intersection of South Chicago and Hoff roads. For a longer trek, the range also can be accessed via the Wauponsee Glacial Trail.