What are the differences between endangered, threatened, imperiled, and at-risk species?

Under the Endangered Species Act (ESA), plant and animal species may be listed as either endangered or threatened. “Endangered” means a species is in danger of extinction throughout all or a significant portion of its range. “Threatened” means a species is likely to become endangered within the foreseeable future.'

States have their own ESA-type laws, so species can have different Threatened/Endangered statuses at the federal and state levels. The USGS typically refers to the federal status unless otherwise noted.

"Imperiled" or "at risk" are not legal terms under ESA, but more biological terms. Generally speaking, they are animals and plants that are in decline and may be in danger of extinction. Those terms can include species that are at low populations and near extinction but still not legally protected under ESA.


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May 20, 2010

Big Invaders and Tiny Fish: Endangered Species Day

Kids! Listen up—it's Endangered Species Day, and we have two podcasts for you: giant, invasive predators that eat endangered animals, and the tiny Devil's Hole pupfish, which lives on a watery shelf no bigger than a walk-in closet.

Shaken, Not Stirred—Watch Devils Hole pupfish deal with a large earthquake that causes

January 5, 2010

Public Lecture: Flight from Extinction: Helping Whooping Cranes Survive

  • Scientists and volunteers are working to restore the Eastern population of the federally listed whooping crane
  • The life history and migration of whooping cranes
Image: An Endangered Red Hawksbill Sea Turtle Swims Over a Threatened Elkhorn Coral in Virgin Islands National Park
January 29, 2008

An Endangered Red Hawksbill Sea Turtle Swims Over a Threatened Elkhorn Coral in Virgin Islands National Park

This photo shows an endangered hawksbill (Eretmochelys imbricata) swimming over a colony of elkhorn coral (Acropora palmata).

USGS scientists are doing research on sea turtles and corals in Florida and the US Virgin Islands.

Image: Hawksbill Sea Turtle (Eretmochelys imbricata)
March 18, 2006

Hawksbill Sea Turtle (Eretmochelys imbricata)

Hawksbill Sea Turtles (Eretmochelys imbricata), such as the one hiding here under a boulder, and Green Sea Turtles (Chelonia mydas) are occasionally seen in Hurricane Hole. Hawksbills feed mostly on sponges while Greens eat mostly sea grasses.

Image: Endangered California Condor
October 18, 2003

Endangered California Condor

An endangered California condor flies over the Bitter Creek National Wildlife Refuge, California. USGS scientists are helping managers understand how California condors use their habitat, gaining valuable information that will help inform not only which potential energy development sites are likely to have the least impact on condors but also which areas of Oregon might be

Attribution: Ecosystems
A manatee swimming in Florida waters.
November 30, 2000

A manatee swimming in Florida waters.

A manatee swimming in Florida waters. USGS photo. 

Image: Endangered Hawaiian Hoary Bat

Endangered Hawaiian Hoary Bat

An endangered Hawaiian hoary bat, a species that is sometimes killed by wind turbines. USGS scientists from Hawaii and Colorado are devising a way to directly observe bat occurrence and behavior at wind turbines using a video system composed of high-powered illuminators and near-infrared cameras.  This new approach images the full rotor-swept areas of wind turbines for

Image: Endangered Burrowing Owl

Endangered Burrowing Owl

An endangered Burrowing Owl near a site in Cape Coral, FL.

Attribution: Ecosystems
Image: An Endangered Honeycreeper, the  `Akeke`e (Kauai Akepa), in Hawaii

An Endangered Honeycreeper, the `Akeke`e (Kauai Akepa), in Hawaii

Many species of Hawaiian honeycreepers have persisted into the 20th century because high elevation rain forests on the islands of Kaua’i, Maui, and Hawai’i are cool enough to limit transmission of introduced avian malaria (Plasmodium relictum). Malaria transmission is tied closely to the effects of temperature on development of malarial parasites within their

Image: Black-footed Ferret

Black-footed Ferret

A ferret gets vaccinated at the USGS National Wildlife Health Center.

Attribution: Ecosystems