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Bird with white body, black head markings and pointed yellow beak sits in beach sand.
Information icon Interior least tern. Photo by USFWS

Interior least tern

Sterna antillarum

Virtual Announcement Event

The U.S. Fish and Wildlife Service (Service) announced the final delisting of the interior least tern on Tuesday, January 12, 2021 during a live virtual event.


Video and audio recordings of the event are available for download.

Introduction

Least terns are the smallest members of the tern family. Terns are generally considered seabirds, but several species are also found along rivers, lakes, or other wetlands. The Interior least tern is a migratory bird species, nesting along freshwater habitats of the Missouri and Mississippi rivers and their major tributaries and overwintering in the Caribbean and South America.

Appearance

Measuring 8 to 9 inches long with a 22-inch wingspan, this tern species is characterized in the breeding plumage by a black crown, white forehead, grayish back and dorsal wing surfaces, snowy white undersurfaces, orange legs, and a black tipped yellow bill. Males and females look alike but immature birds have darker plumage, a dark bill, and dark eye stripes on their white heads. Least terns are distinguished from all other North American terns by their small size. Interior least terns can only be separated from eastern and California least terns by the geographic area used for nesting.

Bird with white plummage, black head markings and pointed yellow beak stands on rocky sand.
Adult interior least tern. Photo by USFWS
Small chick with pale yellow plummage and black spots sits it sand nest with it's head perched between two eggs. Eggs are pale gret with dark spots. Chick and eggs blend into sand background.
Interior least tern chick and eggs. Photo by USFWS

Habitat

Interior least terns generally nest on the ground, in open areas away from trees, and on or near bodies of water that provide them with fish. Although they are primarily found along river channels, they will also nest on reservoirs, sand and gravel mines, coal mines, and industrial sites where conditions are appropriate and occasionally on rooftops of buildings near bodies of water.

Rocky sand river shore. Water and trees visable in background.
Interior least tern habitat, Arkansas River. Photo credit: Robert Zimmer, Flickr Creative Commons https://creativecommons.org/licenses/by/2.0/legalcode

Diet

Interior least terns are primarily fish-eaters and feed opportunistically on small fish species or the young of larger fish species. Prey species include native species such as shad, carps and minnows, freshwater drum, largemouth bass, white bass, sunfishes, and top minnows, as well as invasive species such as silver and bighead carp. On the Missouri River, prey species include emerald shiner, sand shiner, spotfin shiner, and bigmouth buffalo. Least terns will also occasionally feed on aquatic or marine invertebrates. Riverine foraging habitats and fish abundance may be influenced by random hydrological conditions and events and channel engineering.

Historic range

The Service defined the historical breeding range of the Interior least tern to include the Colorado (in Texas), Red, Rio Grande, Arkansas, Missouri, Ohio, and Mississippi Rivers systems from Montana south to Texas, and from New Mexico east to Indiana. However, in order to avoid confusion with eastern least tern, the Service excluded the Mississippi River south of Baton Rouge, Louisiana, the Texas Coast, and a 50-mile zone inland from the coast of Texas from the protected range of Interior least tern.

Current range

The current east to west distribution of summer nesting Interior least terns ranges from the Ohio River, Indiana and Kentucky, west to the Upper Missouri River, Montana. The north to south distribution ranges from Montana to southern Texas. Interior least terns currently nest along more than 2,858 miles of river channels across the Great Plains and the Lower Mississippi Valley, with nesting colonies found in 18 States, including: Montana, North Dakota, South Dakota, Nebraska, Colorado, Iowa, Kansas, Missouri, Illinois, Indiana, Kentucky, New Mexico, Oklahoma, Arkansas, Tennessee, Texas, Louisiana, and Mississippi. This does not include least tern colonies nesting along the coasts of Texas, Louisiana, and Mississippi.

Conservation Challenges

The Service has proposed removing the Interior least tern from the Federal List of Endangered and Threatened Wildlife due to recovery. This determination is based on a thorough review of the best available scientific and commercial data, which indicates that the Interior least tern has recovered and the threats to the Interior least tern have been eliminated or reduced to the point that the species no longer meets the definition of an endangered or threatened species under the Endangered Species Act (ESA).

Recovery plan

The Service approved the Interior Least Tern Recovery Plan on September 19, 1990. The objective of the recovery plan was to meet the standard of recovery that leads to delisting the Interior least tern. Recovery plans provide a road map for the public with site-specific management actions for private, Tribal, federal, and state cooperation in conserving listed species and their ecosystems. A recovery plan provides guidance on how best to help listed species achieve recovery. Recovery criteria are the values by which it is determined that a recovery plan objective has been reached. The Interior least tern recovery plan can be downloaded here at https://ecos.fws.gov/docs/recovery_plan/900919a.pdf.  

Partnerships, research and projects

Federal and state agencies, tribes, non-government organizations, and industry partners all contributed to the recovery of the Interior least tern. Data sources and conservation partners include 19 Service field offices in four regions, five divisions of the U.S. Army Corps of Engineers (Corps) and 13 districts, three U.S. Geological Survey science centers, 18 states, and multiple non-governmental organizations, including conservation organizations, industrial partners, and universities. More than 30 of these groups have been involved in Interior least tern monitoring.

Depending upon local conditions and needs, active management has included: monitoring, protection of nesting areas, improved water flow, dredge material placement, as well as vegetation and predator control. Many of these beneficial activities have become standard practices and will continue following delisting.

The most notable partner aiding in the recovery of the least tern is the Corps, which coordinated the only range-wide monitoring event in 2005. This effort supported the growing population trends observed during the previous two decades through partial range monitoring. The Corps also has jurisdictional authority over much of the species’ range. The Corps’ Mississippi Valley, Southwest, and Northwest divisions all have made formal post-delisting monitoring and conservation commitments that encompass about 80 percent of tern breeding populations.

How you can help

The ESA requires the Service to implement a system in cooperation with the states to effectively monitor the status of a species for a minimum of five years after delisting to ensure that it remains stable. Under their conservation commitments, the Corps will continue to monitor the species as an indicator of riverine ecosystem function. The Service will continue to work with our partners to develop an effective post-delisting monitoring plan and will publish a notice of the availability of the final plan when it becomes available.

Subject matter expert

  • Paul Hartfield, Lead biologist for the Interior least tern, Mississippi Ecological Services Field Office, paul_hartfield@fws.gov, 601-321-1125

Designated Critical Habitat

There is no critical habitat designated for this species.

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register Official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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