Stories in South Dakota

May Nature Notes

May brings baby bison and migrating shorebirds to TNC preserves in South Dakota.

American Bison (Bison bison) roam and graze the spring grasses across the more than 40,000 acre Tallgrass Prairie Preserve in Pawhuska, Oklahoma. At the time of the roundup, most of the approximately 2,000 head of bison had been herded towards the western side of the preserve in zones near the headquarters and corrals. The green grasses and blackened trees are the result of prescribed spring fires, which coupled with grazing bison, make up two major processes vital for maintaining a healthy prairie ecosystem. The bison are currently threatened by an outbreak of Mycoplasma bovis.
Bison South Dakota spring brings bison calves! © Morgan Heim

Newborn bison and returning migrating birds are signs of spring, and both can be seen at Nature Conservancy preserves in May.

Most bison calves are born in May and June. Pregnant cows first chase off their offspring from the previous spring: yearlings that stay with the herd but can no longer rely on their mother’s care once a newborn arrives. Shortly before giving birth, a cow will move to the edge of the herd or leave the group altogether. The process itself takes only about 20 minutes, the calf can stand on its own after another half hour and run with the herd within one to three hours. Newborn bison are reddish-orange, coloration they keep until about 10 weeks old when they transition to the chocolate brown coat typical of yearlings.

Bison calf running
Baby Bison Bison calf running on the prairie. © Josie Briggs
A brown and white striped prairie chicken with large, round orange balls at the neck, strutting through grass.

After their first few weeks, young bison become more adventurous and may wander away from their mothers to explore the herd. They often form nursery groups: two to three dozen calves that are tended by a few cows. This is a good time to watch the young animals – bison watchers can see them learn from their mothers, begin to graze and sort out who is dominant in their groups. 

Bison can be watched at TNC’s Samuel H. Ordway, Jr. Memorial Preserve where the animals roam throughout the central portion of the property. Other good locations to see bison in South Dakota are Wind Cave National Park and Custer State Park in the Black Hills. Bison are wild animals, so always view them from a safe distance.

Close-up view of an Upland sandpiper on a fence post.
Upland sandpiper Close-up view of an Upland sandpiper on a fence post. © Jim Williams

Upland sandpipers are among the many shorebirds that return to South Dakota in April and May. They are unusual in that they are “terrestrial” shorebirds, not closely associated with wetlands like most sandpipers. In fact, they are dependent upon grasslands, preferring to nest in areas with a mix of grasses, even nesting near prairie dog towns. They are common across most of the state, although considered at-risk due to their need for habitat that may be converted to cropland.

Western meadowlark at TNC's Niobrara Valley Preserve, Nebraska.
Western meadowlark Tweet, tweet! Keep an eye out for western meadowlarks this month. © Chris Helzer/TNC

Look for upland sandpipers in open country, often alongside roads or atop fence posts – and listen for their distinctive “wolf whistle.” One place to look for upland sandpipers is TNC’s Sioux Prairie in eastern South Dakota.

Many other migrating birds return to South Dakota in the spring. Bobolinks are conspicuous grassland birds that return from as far away as Argentina to nest. Western meadowlarks singing from the tops of shrubs or fence posts are another sign of spring that can be seen and heard across the state. Look for migrating warblers in wooded areas and wetlands thickets.