Its body is a pale gray with a white belly. The head of the least tern is black with a white forehead and yellow bill. The least tern lays two to four eggs in the sand beginning mid-May. Both parents incubate and feed the young until they are able to fly. The adult birds and young leave the sandbar by late August.
Least terns catch small fish by diving into the water.
Once the young are able to fly, the birds migrate south to the Gulf of Mexico and the Caribbean. The parents return to the same sandbar year after year to nest. In North Dakota the least tern uses sparsely vegetated sandbars along the Missouri and Yellowstone Rivers. Least terns nest in colonies where the nests of other least terns are just a few feet apart. There are approximately 100 breeding pairs of North Dakota.