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Bachman's warbler, the southern acornshell and the upland combshell. Not long ago, those creatures called the rivers of Georgia and the skies above them home. But now, the federal government has confirmed a grim fact that scientists had long suspected: The songbird and two species of freshwater mussels will never be seen again.

On Monday, the animals were among a group of 21 species the federal U.S. Fish and Wildlife Service removed from the due to their presumed extinction.

Many of the species, including the ones once found in Georgia, were added to the list in the 1960s, '70s and '80s. Most, the agency said, were already in severe decline when they were listed. Some may have already been extinct.

"Federal protection came too late to reverse these species' decline, and it's a wake-up call on the importance of conserving imperiled species before it's too late," USFWS Director Martha Williams said in a statement about the extinction declarations.

The news comes after years of reports warning that Earth is in the midst of another mass extinction event that threatens roughly 1 million plant and globally. These species' potential demise is being driven almost entirely by humans, with the destruction of nature and climate change among the main culprits.

Here's more on the animals with Georgia connections that were removed from the list:

Bachman's warbler (Vermivora bachmanii)

Description: A small, migratory songbird, Bachman's warblers were distinguished from their counterparts by their yellow foreheads, necks and bellies, and olive-colored backs and wings. The birds were found primarily in swamps and in forested floodplains along rivers and streams. Their diet consisted mainly of insects.

Historical range: Alabama, Florida, Georgia, North Carolina, South Carolina and Tennessee.

Species listing date: 1967

Last confirmed sighting: 1980s

Cause of extinction: Conversion of forest nesting environment to agriculture, loss of overwintering habitats in Cuba, collection for museum displays, human development, among other possible factors.

Southern acornshell (Epioblasma othcaloogensis)

Description: A small, freshwater mussel that was rarely over an inch in length, the southern acornshell was best identified by its smooth, yellow outer shell. The species was only known to be found in a few streams in the Coosa River Basin and in the Conasauga River.

Historical range: Alabama, Georgia and Tennessee

Species listing date: 1993

Last confirmed sighting: 1973

Cause of extinction: Sediment pollution and other water contaminants

Upland combshell (Epioblasma metastriata)

Description: Larger than the acornshell at around 2 inches long, the upland combshell was another with a brownish yellow shell, occasionally with spots or stripes. The was found mainly in the Black Warrior, Cahaba and Coosa river systems.

Historical range: Alabama, Georgia, Tennessee

Species listing date: 1993

Last confirmed sighting: mid-1980s

Cause of extinction: Sediment pollution and other water contaminants