Midwest Region Endangered Species Conserving the nature of America

Endangered Species Program


The mission of the U.S. Fish and Wildlife Service's Endangered Species program is conserving and restoring threatened and endangered species and their ecosystems.




U.S. Fish and Wildlife

Service in the Midwest


The Midwest Region includes Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio and Wisconsin. Find a location near you.


The Midwest Region includes Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio and Wisconsin.
Find a location near you »

Least Tern (Interior Population)

Sterna antillarum

Fact Sheet


Least tern

Least tern

Photo by Wayne Hathaway for the Tern and Plover Conservation Partnership

The interior population of the least tern (interior least tern) is an endangered species.  Endangered species are animals and plants that are in danger of becoming extinct.  Threatened species are animals and plants that are likely to become endangered in the foreseeable future. Identifying, protecting, and restoring endangered and threatened species is the primary objective of the U.S. Fish and Wildlife Service’s endangered species program.


What is the Interior Least Tern?

Appearance:  The least tern is the smallest tern found in North America.  These 8 to 9 inch birds have a black “crown” on their head, a snowy white underside and forehead, grayish back and wings, orange legs, and a yellow bill with a black tip.


Habitat:  Least terns nest on barren to sparsely vegetated sandbars along rivers, sand and gravel pits, lake and reservoir shorelines, and occasionally gravel rooftops.  They hover over and dive into standing or flowing water to catch small fish.


Reproduction: The interior least tern breeding season is April through August.  Nesting in small colonies, least tern nests are shallow depressions scraped in open sandy areas, gravelly patches, or exposed flats. Both parents incubate their eggs for about 24 days.   Chicks leave the nest only a few days after hatching, but the adults continue to care for them, leading them to shelter in nearby grasses and bringing them food.


Range: Interior least terns breed in isolated areas along the Missouri, Mississippi, Ohio, Red, and Rio Grande river systems.  They winter along coastal areas of Central and South America and the Caribbean Islands, but not a lot is known about their wintering areas.


Why is the Interior Least Tern Endangered?

Habitat Loss or Degradation: Dams, reservoirs, water diversion and other changes to river systems have eliminated most historic least tern nesting habitat. Wide channels dotted with sandbars, which are preferred by least terns, have been replaced by narrow, armor-banked rivers with highly altered flows.  In addition, climate scientists predict significant changes in weather patterns across the country over the next few decades.  That, coupled with increasing demands for water across the terns range, will present ever greater challenges to conservation and water supply management.


Nest Disturbance: Recreational activities on rivers and sandbars disturb nesting least terns, causing them to abandon their nests.  Predation can also be a factor, especially for nesting areas in close proximity to forested corridors.


Least tern chick and two eggs.

A least tern nest is a shallow depression in sand or gravel. The eggs and chicks are well camouflaged.

Photo by USFWS; Jane Ledwin

What Is Being Done to Prevent Extinction of the Interior Least Tern?

Listing: Listing the interior least tern as an endangered species in 1985 provided this bird with Endangered Species Act protection, which increased its visibility and made it a conservation priority for federal agencies working on rivers within the central U.S.  The recent 5-Year Review indicated that interior least tern numbers have increased substantially since listing.  Most of this increase is along the Lower Mississippi River.  The review recommends delisting the tern pending (a) demographic modeling to ensure population trends are sustainable over time and (b) agreements with federal river management agencies to continue current conservation measures to support recovery of the species.


Recovery Plan: The U.S. Fish and Wildlife Service developed a recovery plan that describes and prioritizes actions needed to conserve and improve least tern populations.


Conservation Partnership:A number of partnerships, working through state natural resources agencies, monitor least tern nesting colonies, conduct research to inform river management activities and carry out public awareness programs.


Research and Monitoring: The Interior Least Tern Working Group is a multi-agency group dedicated to improving the collection, storage, analysis, and dissemination of high-quality monitoring data for interior least tern populations.


Habitat Protection: The U.S. Fish and Wildlife Service and other partners work with the U.S. Army Corps of Engineers to ensure their actions along rivers throughout the range of the species continue to provide habitat for nesting least terns. In addition, we work with our state and private partners to protect off-river nesting areas and migration habitats. All these efforts are coupled with continued public education and outreach on the species needs and native habitat needs.


What Can I Do to Help Prevent the Extinction of Species?

Learn: Learn more about the interior least tern and other endangered and threatened species. Understand how the destruction of habitat leads to loss of endangered and threatened species and our nation’s plant and animal diversity. Tell others about what you have learned.


Join: Join a conservation group, many have local chapters, or volunteer at a local nature center, zoo, or wildlife refuge.


Be involved: Advocate for sustainable river management and opportunities where conservation measures work together with other programs to provide community benefits.


Observe: While using rivers for recreation, observe and follow any signs posted to protect colonies of nesting birds.


Protect Water Quality: Protect water quality by minimizing use of lawn chemicals (i.e., fertilizers, herbicides, and insecticides), recycling used car oil, and properly disposing of paint and other toxic household products.


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