On the brink

Gone forever: the great auk

Pinguinus impennis | EXTINCT

The great auk, a large, flightless seabird of the North Atlantic Ocean, was wiped out by overhunting in the 19th century. It is emblematic of human-induced extinctions.

Extinct since 1883: the quagga

Equus quagga quagga | EXTINCT

Hunters brought this South African subspecies of zebra to near-extinction in the late 1800s. Last seen in the wild in 1878, the only remaining captive individual died in Amsterdam in August 1883.

Lonesome George: last of the Pinta Island tortoises

Lipotes vexillifer | EXTINCT

Occasionally, the population of a doomed species declines to a single known individual. Such was the case for Lonesome George, discovered in 1971 on his island in the Galapagos—long after his subspecies was thought to be extinct. He died on June 24, 2012.

From billions to zero: the passenger pigeon

Ectopistes migratorius | EXTINCT

Another sole survivor was Martha, the last passenger pigeon, who died at the Cincinnati Zoo on September 1, 1914. Vast flocks of these birds once darkened the skies of the eastern United States until hunting and deforestation caused their numbers to plummet.

Island extinction: the po'ouli

Melamprosops phaeosoma | EXTINCT

The po'ouli is one of  95 Hawaiian bird species  that are now extinct. Island populations are particularly vulnerable to invasive species introduced—deliberately or inadvertently—by humans.

Vanished: the golden toad

Incilius periglenes | EXTINCT

Formerly endemic to a tiny tract of Costa Rican cloud forest, the golden toad was last seen on May 15, 1989. Some believe it to be the first known extinction caused by climate change. It is symbolic of the plight of hundreds of species.

Climate change victim: staghorn coral

Acropora cervicornis | CRITICALLY ENDANGERED

The numbers of this iconic coral have declined more than 80 percent as a changing climate causes ocean temperatures to increase and chemistry to change. As ocean waters warm and become more acidic, many coral species bleach and ultimately die.

Into oblivion: the Saint Helena olive

Nesiota elliptica | EXTINCT

Although animals usually receive greater attention, plants are also vulnerable to extinction. The Saint Helena olive's limited range, together with logging and loss of habitat, sealed its fate. The last wild tree died in 1994, and the sole remaining cultivated specimen expired in 2003.

Declared extinct: the Chinese paddlefish

Psephurus gladius | EXTINCT

Its numbers historically reduced by overfishing, the prospects for this giant fish of the Yangtze River were dealt a fatal blow when construction of a dam blocked its migration route. No individuals have been seen since 2003; a study published in early 2020  declared it extinct .

On the verge: the vaquita

Phocoena sinus | CRITICALLY ENDANGERED

The number of individuals of this little-known dolphin species was estimated at less than 600 in 1997; according to the  World Wildlife Fund  the current population is about 10 individuals. Mortality due to gill-netting is a primary cause of its disastrous decline. The vaquita's range is restricted to the northern Gulf of California.

Surviving in the wild: the tiger

Panthera tigris | ENDANGERED

The  World Wildlife Fund  estimates that only about 3,900 tigers remain in the wild—a reduction of more than 90 percent over the past century. Thanks to the heroic efforts of conservationists, wild tiger populations are now modestly increasing. Tigers continue to face poaching threats and ever-shrinking habitats.

Surviving in captivity: the Alagoas currasow

Mitu mitu | EXTINCT IN THE WILD

A victim of habitat destruction, this Brazilian bird was last seen in the wild in the 1980s. About 130 individuals live in captivity. In 2019  three pairs  of this species were reintroduced in a tract of Brazil's Atlantic coastal forest, a global biodiversity hotspot. The birds are being carefully monitored, with hopes of future reintroductions.

Captive breeding of endangered animals is a method frequently employed by conservation biologists as a last-ditch effort to avert extinction.

Rediscovered: the hairy-nosed otter

Lutra sumatrana | ENDANGERED

Illegally hunted for meat and medicinal use, this little-known otter was considered extinct until small populations were discovered in Cambodia, Thailand, and Indonesia. It  remains threatened  by hunting and habitat loss.

Many endangered species are difficult to study and poorly understood, complicating efforts to save them.

Reintroduced: the California condor

Gymnogyps californianus | CRITICALLY ENDANGERED

Its population reduced by hunting and habitat loss to just 27 individuals, all wild birds were captured in 1997 in a desperate and controversial effort to save the species. Success of a captive breeding program resulted in their reintroduction to the wild in 1991. As of March, 2020,  337  individuals were flying free in California, Arizona, New Mexico, and Baja California.

Hanging on: the eastern black crested gibbon

Nomascus nasutus | CRITICALLY ENDANGERED

Thought to be extinct, a tiny population of this primate was discovered in northern Vietnam in 2002. It is now one of the world's most endangered primates, with about  250 adult individuals  surviving in the forests of Vietnam and southern China.

Flightless survivor: the kakapo

Strigops habroptila | CRITICALLY ENDANGERED

A tiny population of the world's only flightless parrot survives on three islands off the coast of New Zealand. Once one of New Zealand's most common birds, its population declined to just 62 individuals in 1999. By 2019, conservation efforts had increased its  numbers to 213 , the most in seven decades.

Lost and found: the black-footed ferret

Mustela nigripes | ENDANGERED

This predator of America's great plains was considered extinct until a remnant population was discovered in Wyoming in 1981. A captive breeding program resulted in its reintroduction into its native prairie habitat; populations across several states currently total  about 300 .

The kakapo and ferret represent conservation success stories, and show that protection efforts can work. But when wild populations total only a few hundred individuals, species like these remain highly vulnerable to a variety of threats including disease, climate change, and habitat loss.