Stories in South Dakota

May Nature Notes

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

A bison calf in a grassland.
Bison calf in Colorado. ALL RIGHTS. A baby American bison roams the plains with its mother at the Medano-Zapata Ranch in the San Luis Valley, CO. © Audrey Wolk/TNC

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.

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. 

Upland sandpiper standing on a barbed wire fence.
Upland sandpiper Upland sandpipers are dependent on South Dakota's grasslands for nesting. © 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.

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.