In his 1932 checklist of birds in Missouri, Rudolf Bennitt noted that least terns nested on the Missouri River in Lafayette County. Otto Widmann, in his 1907 book, stated that least terns were common summer residents of both rivers. Modifications that have eliminated sand islands on both the Missouri and Mississippi rivers have caused the terns' nesting range to dwindle. They now nest only in the southeastern tip of the state. Since 1985, researchers have found tern colonies only in or adjacent to Scott, Mississippi, New Madrid and Pemiscot counties.
Terns are expert colonizers when they can find suitable new habitat.
A few of our banded birds also showed up on the Upper Missouri River in South Dakota. Similarly, Missouri sites attract birds from other nesting areas that are undergoing flooding or other habitat disruption. Today the number of least terns in Missouri ranges between 500 and 900 nesting pairs. We are concerned, however, that these sand island nesters are not reproducing at a rate to maintain these numbers. We will continue to monitor them and protect them, but our research confirms they can survive only if they have suitable big river sand island habitat.