Conservation

Population: Around 180 in captivity; small reintroduced group in Brazil

The bird that inspired Rio — declared extinct in the wild, now fighting back

Population: Extinct in the wild since 1994; maintained at several breeding facilities

A toad that vanished from Earth — and lives on in human hands

Population: Extinct in the wild since 2000; around 1,700 in managed herds; a reintroduced population in Chad is now self-sustaining

Hunted to extinction across an entire continent — and now being walked back

Population: Two individuals alive — both female, both at Ol Pejeta Conservancy, Kenya

Two females are all that remain — kept alive while scientists race to save the species through IVF

Population: Declared functionally extinct in 2006; possibly a handful surviving, unconfirmed

The first dolphin driven to extinction by humans — and a warning that went unheeded until it was too late

Population: Three individuals known in 1997; last confirmed individual died in captivity in 2004

One of Hawaii's rarest birds — last seen in the wild in 2004, in a story of missed chances

Population: One individual survived until 2016 — named Toughie. No others are known.

The last of its kind was a single frog named Toughie, who lived alone at the Atlanta Botanical Garden until 2016

Population: Around 115 in captivity; reintroduction attempts ongoing in Hawaii

One of the world's only tool-using birds outside of primates — extinct in the wild and being carefully reintroduced

Population: Fewer than 10 individuals

The world's rarest animal — fewer individuals than any other species, wild or captive

Population: Approximately 20 wild individuals

America's most endangered wolf — and a comeback story in progress

Population: Around 100 individuals in the wild

The world's rarest big cat — and quietly recovering

Population: Around 76 individuals

One population, one park — the most precarious large mammal on Earth

Population: Unknown — possibly fewer than 100

The Asian unicorn — one of the most mysterious large animals on Earth

Population: Around 400 individuals

The smallest and darkest tiger subspecies — and the last tiger to survive on an Indonesian island

Population: Around 1,000 individuals

The only great ape whose population is increasing — and a conservation success built on tourism revenue

Population: Estimated 8,000 nesting females globally

The reef's essential sponge controller — whose shell drove it to the edge of extinction

Population: Around 6,500 individuals

Poached to 2,500 individuals by 1995 — and now recovering through one of Africa's most intensive protection programs

Population: Around 100,000 Bornean; around 14,000 Sumatran; around 800 Tapanuli (most endangered great ape)

The only great ape outside Africa — losing 25 football fields of forest every hour

Population: Around 1.3 million — recovered from 50,000 after a catastrophic die-off, but still highly vulnerable

Lost 62% of its entire global population to a bacterial outbreak in three weeks — and then staged one of conservation's most dramatic recoveries

Population: Around 250 individuals — every single one has a name

The world's only flightless parrot — individually named, individually managed, and genuinely recovering

Population: Around 560 individuals — brought back from 27

Extinct in the wild in 1987 — every condor alive today descends from 27 birds collected before the species vanished

Population: Fewer than 1,000 in the wild; millions in captivity worldwide

Extinct in the wild except for a few canals in Mexico City — while millions live in tanks and laboratories worldwide

Population: Unknown — population data is almost nonexistent due to their secretive nature

The world's most trafficked mammal — over a million taken from the wild in the past decade

Population: Around 6,600 adults

The most successful hunter in Africa — and one of its most misunderstood

Population: Estimated 10,000–25,000 individuals globally

Hunted to near-extinction in 50 years — slowly recovering, but still threatened by ship strikes and entanglement

Population: 4,000–6,500 individuals

Ghost of the mountains

Population: Around 1,900 individuals

A genuine conservation success story

Population: Around 415,000 savanna elephants; around 100,000 forest elephants (forest elephants separately listed as Critically Endangered)

The largest land animal engineers entire ecosystems — and is killed for teeth it uses to dig water for other species

Population: Around 7,000 individuals

The fastest land animal can't roar, loses most of its kills to other predators — and is running out of room to run

Population: Around 26,000 individuals

The species most directly threatened by climate change — with some populations projected to disappear within decades

Population: Approximately 34,000–36,000 nesting females; Pacific population Critically Endangered

The largest living turtle dives deeper than most submarines and navigates by magnetic field across entire ocean basins