Least terns are migratory shorebirds, and the smallest members of the gull and tern family. They measure approximately 9 inches in length, and have characteristics that are both aero and hydro dynamic, including narrow, pointed wings...a split tail...and webbed feet. There is nothing ornate, or flashy about the color of least terns, yet they are strikingly beautiful in their simplicity. They have a black capped crown that extends forward over each eye, a snowy white forehead, neck and underside, and gray wings, back and tail.
Interior least terns are piscivores, or fish eaters, and generally fish the shallow waters of rivers, lakes and streams, targeting any small fish that falls within a certain size range.
The birds winter along the coastlines of the Gulf of Mexico, and northern coast of South America, and migrate every spring to interior reaches of rivers in the central United States. They breed in the Mississippi and Rio Grande River Basins from Montana to Texas and from eastern New Mexico and Colorado to Indiana and Louisiana, with distribution generally restricted to those river segments least affected by dams and channelization.
Courtship basically consists of nest scraping activities, and a mating ritual that includes the male’s offering of fish to the female. Once paired, the birds remain monogamous.
Egg-laying begins in late May. A female usually lays a clutch of one to three eggs, and shares nesting duties with her mate. It takes about 18 days for the nest to be incubated until successfully hatches. Least terns will renest until late July if a clutch or brood is lost.
Adults share the duties of feeding their chicks until they are fully fledged. The chicks are hatched with down, and don't acquire plumage until their first molt in approximately one year. They remain in the nest for about a week after hatching, then start wandering away from the nest in search of shade and shelter. At feeding time, the young terns wait along the shoreline for their parents to bring them fish.
Least tern chicks are capable of flight within 3 weeks of hatching, but the parents continue to feed them until they leave the sandbars for their fall migration.
Thank you for your patience.
The interior least tern was listed as a federally endangered species in 1985, and remains a species of concern because of its low numbers, and the degradation of habitat in certain areas throughout its range.
In an effort to insure the future of threatened and endangered species, like the least tern, the piping plover, and the pallid sturgeon, the U.S. Fish & Wildlife Service has proposed changes to the way the Missouri River is managed.
The development of the Missouri and Mississippi Rivers is largely due to the needs of agriculture, commerce, and communities. Farmers need irrigation, commerce needs navigation, and communities along the river want to lessen the impact of floods. As a result, legislation has enacted laws that essentially allowed the Army Corps of Engineers to make changes to the river.
Those legislative policies are often in conflict with the needs of endangered species, such as the least tern. As a result, most of our large stem rivers, such as the Mississippi and Missouri Rivers, have been altered to such an extent, protection under the ESA is the only hope for recovery for least terns, piping plovers, pallid sturgeon, and other endangered species who depend on the large river systems for survival.
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