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Life Along a
Prairie River

Exploring the ecology of the wide and sandy rivers of the Great Plains

Interior least terns are a subspecies of the least tern that live in the Great Plains and Mississippi Valley. Other least tern subspecies live on the Gulf, Atlantic, and California coasts. Least terns are the smallest member of the gull family of birds. In Oklahoma they can be found along the large prairie rivers and Great Salt Plains from May to September. During this time they court mates and set up nesting colonies. Typically people think birds nest in trees, but least terns (and many other species) nest on the ground. They scrape away the ground to form a shallow bowl in bare sand, gravel, or shells on dry mudflats, salt plains, or in sand and gravel pits. Both the male and female sit on the nest of two or three speckled eggs for about three weeks. After hatching, the chicks are tended by both parents. They can fly at three weeks old, but remain dependent upon the adults for food. Least terns eat primarily small fish, but may also eat aquatic invertebrates.

Preparation for migration begins in mid-July and birds have left Oklahoma by early September. During this time, terns congregate in large flocks and fuel up for the long trip to South America. Juvenile terns are able to practice their fishing skills and learn to become independent during pre-migration. Little is known about their life in South America during the winter.

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