In spite of the tremendous efforts and determination of wildlife preservers and advocates, America's dearest ivory-billed woodpecker and 22 more birds, fish and other species were officially declared extinct.

The U.S. government announced on Wednesday the extinction of the 23 species, however, it could be that one or more could reappear in the future.

Government scientists point climate change as the primary driver among other pressures. If warming on Earth continues rapidly, more disappearances could become more common and many fear that this could ultimately imperil plants and wildlife.

A Time of an 'Extinction Crisis'

The ivory-billed woodpecker (Campephilus principalis) happens to be the best-known species that the U.S. Fish and Wildlife Service declared as 'Critically Endangered'. These birds are native to old-growth and temperate coniferous forests in the southeastern U.S. and Cuba.

Although there are several reports of appearances in the recent decade which prompted searches in the swamps of Arkansas, Louisiana, Mississippi and Florida, these sightings were never confirmed.

One among other disappearing species is the flat pigtoe or Marshall's mussel, a freshwater mussel in the southeastern U.S. but has not been seen since 1980.

"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 "Andy" Ford, a U.S. Fish and Wildlife Service biologist in Tennessee who specializes in freshwater mussels.

While the reason behind their extinction may vary, human activities seem to be the principal cause.

It is unusual for wildlife officials to give up on these species, believing there is at least a slight chance of survival when the 23 species were added to the endangered list in the 1960s, however, to no avail, the status becomes final after the three-month comment period.

A 'Premature' Declaration

Bird biologist John Fitzpatrick of Cornell University believed it was premature to call off preservation efforts after millions have already been spent. "Little is gained and much is lost," he said. Fitzpatrick claims in a 2005 study that woodpecker had been rediscovered in eastern Arkansas.

"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," he said.

Craig Hilton-Taylor of the group added that there can be unintended but damaging consequences if extinction is declared prematurely. "Suddenly the (conservation) money is no longer there, and then suddenly you do drive it to extinction because you stop investing in it," he said.

In Federal officials' defense, the extinctions declaration was to clear a backlog of those species not acted upon for years and make resources for species that still have a chance for recovery.

As climate change makes this recovery harder, their main focus at the moment is no longer on individual species, but a broader goal to preserve their habitat.