Endangered species: Where are they now

The first list of endangered and protected species was compiled in 1966 as part of the Endangered Species Preservation Act. The list included just 14 mammals, including the grizzly bear, as well as birds, reptiles and amphibians. In 1973, The Endangered Species Act, which will celebrates its 40th anniversary this December, added invertebrates to the list and further increased conservation efforts.

Read on to learn more about how critically endangered species have fared since these first lists were compiled.

Bald Eagle

This symbolic bird hit an all-time population low of 417 pairs in 1963 and was included on the original list of threatened and endangered species.

Today, thanks to the banning of DDT, captive breeding programs, habitat protection and other measures, populations have soared to over 10,000 pairs, according to the U.S. Fish and Wildlife Service. The Bald Eagle was removed from Endangered Species Act protection in 2007, but remains protected by other laws.

Florida Manatee

Manatee_resting_at_Three_Sisters_Springs_Keith_Ramos.jpg — Keith Ramos/U.S. Fish and Wildlife Service

Also known as a sea cow, this is one of the most beloved animals on the original list of endangered species. Manatee populations in Georgia and Florida were threatened primarily by collisions with boats and other watercraft.

After increased conservation efforts, including manatee speed zones, a high count of 5,076 animals was recorded in 2010. However, the IUCN Red List of Endangered Species still classifies these gentle giants as vulnerable and predicts further population decline due to habitat loss.

Black Footed Ferret

Ryan Hagerty/U.S. Fish and Wildlife Service

Once believed to be extinct, these ferrets have made a remarkable comeback.

Nearly all wild black-footed ferrets were wiped out by disease and the extermination of prairie dogs, which were the animals' main food source. But a small population of the species was discovered in 1981 and was successfully bred in captivity. Today, more than 1,000 ferrets live in the wild and their numbers are expected to increase.

Brown Pelican

Tom MacKenzie/U.S. Fish and Wildlife Service

The notorious pesticide DDT was responsible for these pelicans being declared endangered in 1970.

Aggressive conservation efforts, including the ban on DDT, led to a full recovery and the bird is no longer listed under federal protection.

Loggerhead Sea Turtle

Becky Skiba/U.S. Fish and Wildlife Service

Loggerhead Sea Turtles were added as a threatened species in 1978 and in 2011, four sub-populations of loggerheads were listed as threatened while five more were listed as endangered. Loss of suitable nesting habitat from coastal development, disorientation of hatchlings by beachfront lighting, marine pollution, watercraft strikes and commercial fishing operations have all led to loggerhead population decline, according to the U.S. Fish and Wildlife service.

But not all hope is lost for these turtles. Targeted nest protection and habitat conservation efforts have led to some progress and in 2012, the Archie Carr National Wildlife refuge in Florida reported 18,797 loggerhead nests, a record high.

Mountain Gorilla

Richard Ruggiero/U.S. Fish and Wildlife Service

Habitat loss, poaching and illegal trade has threatened all great ape species with extinction, but with the help of aggressive conservation efforts, including the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in 1973, mountain gorilla populations have increased modestly.

According to the IUCN Red List there are now approximately 680 individual mountain gorillas living in two isolated populations in central Africa, up from an estimated 320 gorillas in 1989.

Whooping Cranes

Klaus Nigge/U.S. Fish and Wildlife Service

Once numbering in the thousands, habitat loss and hunting dwindled the population of these elegant birds to only 15 adults in 1938, according to the IUCN Red List. Whooping Cranes were included on the original endangered species list in 1966.

An innovative human-led migration program helped cranes to rebound in 2001. The species is still endangered, but populations have made gains. Recent numbers estimate the total wild population at 382 cranes.

See more: Whooping Cranes of the Aransas Wildlife Refuge

Higgins Eye Pearly Mussel

Included on the first list of invertebrate species to gain federal protection in 1976, this freshwater mussel species was originally threatened by habitat loss and pollution. Zebra mussels, an invasive species which attaches to the shells of other mussels, have also become a significant threat.

Government agencies have developed methods for breeding Higgins Eye Mussels in captivity and since 2002, the U.S. Fish and Wildlife Service says they have released 42,000 mussels into the Mississippi River watershed.

California Condor

Included on the original endangered and threatened species list, only 22 wild California Condors remained by 1982. All of these birds were captured by the U.S. Fish and Wildlife Service in an effort to save them from extinction.

After an intensive captive breeding program, the condors were re-introduced to the wild in 1991. The IUCN Red Book still classifies these condors as critically endangered, with just an estimated 213 individual birds in the wild, but populations are expected to increase.

Indiana Bat

Ann Froschauer/U.S. Fish and Wildlife Service

These bats, found across the eastern United States, were included on the original endangered species list. Large numbers of the cave-dwelling bats died after people disturbed their winter hibernation.

The bats were further threatened in 2006 when white-nose-syndrome, a fungal disease, killed more than 5.7 million bats, including Indiana bats, in the U.S. and Canada. The U.S. Fish and Wildlife Service has called the syndrome "the most deadly wildlife disease of our time."

Polar Bear

Gary Kramer/U.S. Fish and Wildlife Service

The polar bear was protected as a threatened species in 2008 due to the loss of its primary habitat, sea ice. This was the first time a mammal was given protection under the Endangered Species Act due to the impacts of climate change, according to the U.S. Fish and Wildlife Service.