The U.S. Fish and Wildlife Service will remove 21 species from the nation's endangered species list because they are considered extinct, but the much-debated ivory-billed woodpecker won a temporary reprieve, the agency announced Monday.

Birds, mussels, fish and a bat are among the 21 extinct species, including eight birds found only in Hawaii and eight mussels that had been found primarily in Alabama and parts of the Southeast. The list also includes the Bachman's warbler, once found in the Southeast.

“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,” fish and wildlife service director Martha Williams said in a news release.  

One plant, a Hawaiian member of the mint family originally thought to be extinct, was removed from the proposal after a review found habitats where the plant might still be found. 

“My heart breaks over the loss of these 21 species,” said Noah Greenwald, endangered species director at the Center for Biological Diversity. “These plants and animals can never be brought back. We absolutely must do everything we can to avert the loss of even more threads in our web of life.”

Is the ivory-billed woodpecker extinct?

When the ivory-billed woodpecker, once known as “the Lord God bird” for its massive 30-inch wing span, was included in the delisting proposal issued two years ago, controversy erupted among ardent supporters who believe the bird is still found in remote swamps between Arkansas and Mississippi. 

On Monday, the agency stated the agency will "continue to analyze and review the information before deciding whether to delist the ivory-billed woodpecker."

During a May 2022 public hearing on the proposed woodpecker delisting, ornithologist John Fitzpatrick, a former director of the Cornell Lab of Ornithology, told the agency the decision would be "premature," saying it would be a "casual dismissal of a number of pieces of evidence that the bird still exists."

The nation's largest woodpecker surged into conversations in 2005, when Fitzpatrick and scientists with the wildlife service, Cornell University and the Nature Conservancy announced a few seconds of an ivory-billed woodpecker's flight had been caught on video. Months later, a sighting also was reported by the U.S. Naval Research Laboratory in Mississippi.

Both announcements, however, were greeted with skepticism and triggered renewed, in-depth explorations to try to prove the bird's existence.

Solid evidence has eluded researchers hoping to convince the world the birds survive. As part of the latest effort to convince the wildlife service to hold off on declaring the woodpecker extinct, a group of experts in May released new videos and photographs taken by drones and trail cameras in a study in a peer-reviewed journal.

Controversy lingers however as many ornithologists remain unconvinced the ivory-billed woodpecker survives.

"While we live in hope, we have yet to see any compelling recent evidence for the continued existence of the Ivory-billed Woodpecker, and sadly presume it is most likely extinct," Michael J. Parr, president of the American Bird Conservancy, said Monday. "It seems like a good precautionary step to omit it from the list for now but without a clear photo – which we don’t have - we are far short of any sort of proof of life, sadly."

More:America's birds are under siege. These are among the most at risk for extinction.

A grim reminder

The extinctions highlight the importance of the nation’s Endangered Species Act and conservation before declines become irreversible, wildlife groups and the fish, and wildlife service said Monday. The decision also shows how human activities – such as development and the spread of invasive species – can cause species to decline and disappear. 

For example, the construction of dams and poor water quality are two major reasons why scientists say many mussels in the Southeast are either extinct or threatened with extinction.

In Hawaii, habitat destruction and loss to development and agriculture are blamed for the loss of many bird species. The introduction of mosquitoes, which were not native to the islands and brought new diseases, "provided the nail in the coffin," the Center for Biological Diversity said.

A study released Monday by scientists at the University of Florida showed a decline in bird biodiversity across the United States in both urban and agricultural areas as the result of people modifying and disturbing their habitats.

The change in status for the 21 species should be a reminder that the act’s purpose is to be “a safety net” to try to prevent species from becoming extinct, the Fish and Wildlife Service said Monday. “The ultimate goal is to recover these species, so they no longer need the Act’s protection.”

Many of the 21 species named in the decision announced Monday already were in low numbers or possibly extinct when the species were added to the endangered species list, the service said.

A loss of biodiversity worldwide

Monday's announcement "underscores the severity and consequences of the global biodiversity crisis,” said Danielle Kessler, director of the International Fund for Animal Welfare. “The threat of extinction is becoming a reality for a growing number of imperiled species, and this serves as a grim and urgent reminder that robust support for our nation’s bedrock wildlife protection laws remains critical.”

Scientists from around the world warn the planet is at risk of losing more than a million species in the coming decades if swift action isn’t taken to protect more of the natural world, stop exploitation of species, address climate change, reduce pollution and stop the spread of alien invasive species, the Center for Biological Diversity said Monday.

More:'Climate captives': Frogs, salamanders and toads dying rapidly as Earth warms, study says

“Few people realize the extent to which the crises of extinction and climate change are deeply intertwined,” Greenwald said. “Both threaten to undo our very way of life, leaving our children with a considerably poorer planet. One silver lining to this sad situation is that protecting and restoring forests, grasslands and other natural habitats will help address both.”

In a fish and wildlife service story published in August, the dean of Alabama's scientists studying freshwater mussels, Paul Johnson, said: "Every time you lose a species, it’s like burning a scientific book."

 The final rule will become effective 30 days after the rule’s publication in the Federal Register on Tuesday.