The US Fish and Wildlife Service will announce 23 new extinct species Wednesday, including the ivory-billed woodpecker — the most well-known animal of the doomed lot.
Government scientists have exhausted all efforts to locate the 22 animals and one plant in recent decades, according to wildlife officials.
On the list are 11 birds, eight freshwater mussels, two fish, a bat and a plant, the New York Times reports. The full list containing the names of the species is yet to be released.
The 23 species were initially believed to have had a slim chance of survival when they were each added to the endangered list from the 1960s onwards — but many were likely already extinct when the Endangered Species Act passed in 1973, officials say.
Among the best-known to be declared extinct is the ivory-billed woodpecker.
In recent decades, the bird had sparked a frenzy of fruitless searches in swamps across Arkansas, Louisiana, Mississippi and Florida following unconfirmed sightings.
Others, including the freshwater mussel known as a flat pigtoe, had only been spotted in the southeastern US a handful of times before never being seen again.
Hawaii has the most species on the list, including eight woodland birds and one plant.
The most recent to vanish was the teeny po’ouli bird – known as a honeycreeper – that was discovered in 1973. Only three remained by the late 90s, including one male and two females.
The male bird was captured but died in 2004, and the females weren’t seen again.
Officials say that factors between the disappearances of the 23 species range from climate change, overdevelopment, invasive species and animals being captured by humans.
Since the Endangered Species Act passed, 54 species in the US have been removed from the endangered list after their populations recovered. Until now, 11 species had been declared extinct in the US.
About 903 species have been declared extinct across the world.
Officials will now start a three-month comment period before the extinct status of the 23 new species added to the list becomes final.
Still, some scientists are holding out hope that one or more of the 23 could reappear.
Cornell University bird biologist John Fitzpatrick, who is a leading figure in the hunt for the ivory-billed woodpecker, insists it is premature to call off the search given the millions of dollars spent so far.
“A bird this iconic, and this representative of the major old-growth forests of the southeast, keeping it on the list of endangered species keeps attention on it, keeps states thinking about managing habitat on the off chance it still exists,” Fitzpatrick told the Associated Press.
He added that “little is gained and much is lost” with the extinction declaration.
With Post Wires