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Two small white birds with yellow beaks and black marking on head on the beach
Information icon Interior least terns. Photo by USFWS

Removal of interior least tern from the list of endangered and threatened wildlife - Questions and answers

What is an interior least tern?

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. Least terns feed primarily on small fish.

When was the interior least tern listed under the Endangered Species Act (ESA)?

On May 28, 1985, the U.S. Fish and Wildlife Service listed the population of least tern that occurred throughout the interior of the United States as an endangered species.

Why was the interior least tern listed under the ESA?

Interior least terns historically nested along sand and gravel bars of the Lower Mississippi River and its major tributaries, including the Missouri, Red, Ohio, and Arkansas rivers. At the time of listing, the interior least tern was believed to have been eliminated from much of this summer nesting range by the construction of dams that inundated and destroyed their nesting islands and bars and altered flows or other forms of river engineering, such as channelization. There were also a number of proposed water withdrawal projects on the southern plains that were potential threats to their habitats. In 1985, the population was estimated at fewer than 2,000 adults nesting in a few dozen scattered colonies along the Mississippi River and its tributaries.

How many interior least terns are there now?

Since being protected under the ESA, the numbers and distribution of interior least terns has steadily increased. They currently number approximately 18,000 birds.

Where are interior least terns found?

Interior least terns currently nest along more than 2,800 miles of river channels across the Great Plains and the Lower Mississippi Valley, with nesting colonies documented in Montana, North Dakota, South Dakota, Nebraska, Colorado, Iowa, Kansas, Missouri, Illinois, Indiana, Kentucky, New Mexico, Oklahoma, Arkansas, Tennessee, Texas, Louisiana, and Mississippi.

Where do interior least terns nest?

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, industrial sites where conditions are appropriate and occasionally on rooftops of buildings near bodies of water.

How does the Service determine if a species has recovered and no longer meets the definition of threatened or endangered under the ESA?

The Service periodically conducts reviews of the status of all listed species, as required by the ESA, and considers several factors in determining if they have recovered. These factors include population size and distribution, the current and future status of the species, and known and potential threats. The Service conducted a thorough review of the interior least tern and found that the inland populations of the species have recovered based on all criteria measured. These include an increase in abundance and distribution, implementation of beneficial management practices across its range, and existing regulatory mechanisms that protect the tern and other migratory birds.

What conservation actions led to the recovery of the interior least tern?

The efforts of 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.

What is the process for delisting under the ESA?

To delist a plant or animal, the Service must first publish a proposed rule in the Federal Register explaining why the species no longer warrants protection under the ESA. We evaluated the species’ needs, current conditions, and future conditions in preparing a rule proposing to delist the interior least tern which published in October 2019. We sought and evaluated comments from independent specialists to ensure that our determination was based on scientifically sound data, assumptions, and analyses. We also invited these peer reviewers to comment on the draft post-delisting monitoring plan. We considered all comments and information we received during the public comment period on the proposed delisting rule and the draft post-delisting monitoring plan when developing this final rule. We have now published a final rule delisting the tern, which will take effect 30 days after its publication.

Will the interior least tern continue to receive protections after delisting?

The interior least tern will continue to be protected under the Migratory Bird Treaty Act (MBTA), which protects it and its parts, nests, and eggs from “take” and trade. Federal permits are also required under the MBTA for certain actions like scientific collection and relocation.

Executive Order 13186 (Responsibilities of Federal Agencies to Protect Migratory Birds) requires all federal agencies to use their authorities and conduct their actions to promote the conservation of all migratory bird populations. Actions authorized by EO 13186 that may benefit the interior least tern include: avoiding and minimizing adverse impacts to migratory birds; habitat restoration and enhancement and preventing pollution or detrimental alteration of migratory bird environments; designing habitat and population conservation principles, measures, and practices into agency plans and planning processes; and promoting research and information exchange, including inventorying and monitoring of migratory birds.

The interior least tern also continues to be considered under other federal environmental statutes and regulations such as the National Environmental Policy Act and Clean Water Act, which contain provisions emphasizing the protection and restoration of ecosystem function and quality. State laws protective of native wildlife continue to apply to the interior least tern.

Most states and industries with active management and monitoring are expected to continue conservation actions.

Will the status of the interior least tern continue to be monitored?

Yes. 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 is also continuing 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.

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