The term “endangered species” usually brings to mind charismatic animals—fluffy pandas and majestic tigers. But there are thousands of lesser-known species that are in greater danger of disappearing.

These animals, categorized as “critically endangered” by the International Union for Conservation of Nature and Natural Resources (IUCN), face what the organization calls “an extremely high risk of extinction in the wild.”

“These species are really on the edge, in need of serious intervention,” says Barney Long, Director of Species Conservation in the United States for the World Wildlife Fund. “They won’t recover on their own.”

Two big threats are driving these animals toward extinction: habitat loss and poaching.

To mark Endangered Species Day in the U.S. (May 15), here are pictures of 12 endangered species around the world, taken from National Geographic’s archive.

By Anna Lukacs
Photo gallery by Mallory Benedict
Source: news.nationalgeographic.com

Ruffed Lemur

A black and white ruffed lemur climbs a tree in Madagascar’s Mantadia National Park. Their ability to thrive in captivity makes them ideal candidates for reintroduction into protected habitats.

PHOTOGRAPH BY KEVIN SCHAFER, MINDEN PICTURES

Sumatran Rhino

Rapunzel, a Sumatran rhino, was rescued and lived at the Bronx Zoo until her death in 2005. Largely due to poaching, Sumatran rhinos are now on the brink of extinction, with fewer than 200 remaining in the wild.

PHOTOGRAPH BY MICHAEL NICHOLS, NATIONAL GEOGRAPHIC CREATIVE

Lemur Leaf Frog

A closeup of a lemur leaf frog in Costa Rica. Primarily found in Central America, the lemur leaf frog has experienced severe population decline as a result of chytridiomycosis, an infectious disease of amphibians caused by the chytrid fungus.

PHOTOGRAPH BY MICHAEL AND PATRICIA FOGDEN, MINDEN PICRTURES

Monk Seal

A Hawaiian monk seal swims in the French Frigate Shoals in the northwestern Hawaii. Monk seals have become critically endangered because of increased ocean pollution, coastal habitat loss, and fishing gear that entangles them.

PHOTOGRAPH BY BILL CURTSINGER, NATIONAL GEOGRAPHIC CREATIVE

Bog Turtle

Joel Sartore photographed this bog turtle as part of the Photo Ark project, which aims to document all of the world’s 12,000 captive species. Bog turtles’ wetlands habitat is threatened by extreme weather connected to climate change.

PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC CREATIVE

Vultures

Indian white-backed vultures swarm a rhinoceros carcass in India. Vultures across Asia are declining as a result of feeding on livestock carcasses that contain the poisonous veterinary drug, diclofenac.

PHOTOGRAPH BY STEVE WINTER, NATIONAL GEOGRAPHIC CREATIVE

Vaquita

The world’s rarest marine mammal, this vaquita was caught in a gill-net in Mexico’s Gulf of California. Less than 100 of these small porpoises remain. The Mexican government’s recent ban on the illegal fishing method has renewed hope for the animal.

PHOTOGRAPH BY FLIP NICKLEN, MINDEN PICTURES

Pangolin

A Sunda pangolin at the Carnivore & Pangolin Conservation Center in Vietnam. Pangolins are targeted by poachers who export the mammals’ unique scales and meat to China and Vietnam.

PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC CREATIVE

Iberian Lynx

A wild Iberian lynx stands in Sierra de Andújar Natural Park in Andalusia, Spain. The decline in Spain’s rabbit population—the lynx’s main food source—and  habitat loss threaten the lynx’s survival.

PHOTOGRAPH BY WILD WONDERS OF EUROPE/OXFORD/NATUREPL.COM

Spix’s Macaw

Spix’s macaws, the inspiration for the film “Rio,” perch on a branch at Sao Paulo Zoo in Brazil. Because of habitat destruction and the illegal bird trade, the rare blue parrot only exists in captivity. The last known wild-born Spix’s macaw died in 2000.

PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC CREATIVE

Cuban Crocodile

A submerged Cuban crocodile raises its head above water. Interbreeding with native American crocodiles has resulted in hybridization and the loss of the Cuban crocodile’s genetic identity.

PHOTOGRAPH BY STEVE WINTER, NATIONAL GEOGRAPHIC CREATIVE

Western Lowland Gorilla

A western lowland gorillas sits in Tchimpounga Reserve in the Republic of the Congo. The species has declined by 60 percent in the last 20-25 years, mainly due to commercial hunting and the Ebola virus.

PHOTOGRAPH BY MICHAEL NICHOLS, NATIONAL GEOGRAPHIC CREATIVE