The U.S. Fish and Wildlife Service declared 23 species extinct on Wednesday.

The species were originally a part of the Endangered Species Act, but government scientists decided that the search for them had finally been exhausted. 

The species were added to the Endangered Species Act beginning in the 1960s. 

“The Endangered Species Act wasn’t passed in time to save most of these species,” Noah Greenwald, endangered species director at the Center for Biological Diversity, told The New York Times. “It’s a tragedy.”

Among the recently added extinct species is the well-known ivory-billed woodpecker, otherwise known as the "Lord God Bird." 

“The fact that this bird is so critically endangered has been true since the 1890s, and it’s fundamentally a consequence of the fact that we cut down every last trace of the virgin forest of the Southeastern U.S.,” said John W. Fitzpatrick, director emeritus of the Cornell Lab of Ornithology. “We took all that away.”

It was common for people to go on searches in hopes to find this specific bird in its natural habitat along swamps in southern states of the U.S., as it had often been a favored bird. 

“This is not an easy thing,” said Amy Trahan, the FWS biologist who declared the ivory-bill woodpecker extinct. “Nobody wants to be a part of that. Just having to write those words was quite difficult. It took me a while.” 

The newly added extinct species also includes eight Hawaiian birds including the Kaua’i ’o’o and the Maui ’akepa along with some fish, mussels, and plants. 

“When I see one of those really rare ones, it’s always in the back of my mind that I might be the last one to see this animal again,” said Anthony Ford, an FWS biologist in Tennessee who specializes in freshwater mussels.

It’s a hard process to declare species extinct. When they are added to the Endangered Species Act it means there is hope for them to last. Environmental factors like destroying forests, water pollution, and hunting have become too prominent for some to survive.

Government scientists warn that climate change, on top of the other environmental factors, is causing more animals to become extinct at an accelerated rate. 

“With climate change and natural area loss pushing more and more species to the brink, now is the time to lift up proactive, collaborative, and innovative efforts to save America's wildlife,” Interior Secretary Deb Haaland said in a statement.  “The Endangered Species Act has been incredibly effective at preventing species from going extinct and has also inspired action to conserve at-risk species and their habitat before they need to be listed as endangered or threatened. We will continue to ensure that states, Tribes, private landowners, and federal agencies have the tools they need to conserve America’s biodiversity and natural heritage.”