Oklahoma Natural Areas Registry

Canadian River Interior Least Tern Preserve, Cleveland and McClain Counties

Least Terns are migratory birds related to gulls. Their name comes from being the smallest of all American tern species. There are three populations of Least Terns in the U.S. Oklahoma is one of many states in which the Interior Least Tern (Sterna antillarum athalassos) breeds. During the winter the Interior Least Tern lives off the coast of northern South America. They return to Oklahoma and other central states in April and May to build nests and raise young.

Interior Least Tern nests are only depressions in the sand on the shores and islands of rivers.

The nests are very simple - only shallow depressions in the sand bars of wide prairie rivers. The major reason for the decline in this bird is the loss of breeding habitat. Damming and impoundments of the river eliminate spring floods that maintain sandbars. Fluctuations in the water level of rivers can cause nests to be washed away or exposed to predators when the water level is too low.

The nesting habitat is also vulnerable to human activity along the river. Sand excavation affects the maintenance of sand bars and and destroys nests when conducted in spring and summer. Recreational use of the sandy areas along rivers also disturbs the nesting birds and ruins nests.	Nests are well camoflagued and humans can inadvertantly destroy nests while enjoying a day at the river.
ATV use has increased along the rivers where terns nest and consequently are negatively affecting breeding success of the birds.
The Canadian River Interior Least Tern Preserve is one of four registered natural areas in Oklahoma that provide habitat for nesting terns. This preserve is encompasses approximately 20 miles along the Canadian River south of Oklahoma City to the town of Purcell. Over 20 private and public landowners are have committed to protecting this endangered bird.

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Oklahoma Department of Wildlife Conservation