Pictures: 14 Rarest and Weirdest Mammal Species Named

4. Greater Short-Tailed Bat

Illustration by Peter Schouten

The greater short-tailed bat (shown in an illustration) is likely totally gone from its native islands off New Zealand. The ground-dwelling bat is defenseless against voracious, introduced rats and has not been seen since 1967. (See "Extinct Walking Bat Found.")

Hopes were raised a few years ago when a scientist recorded a call that could belong to the greater short-tailed bat.

But a local Maori tribe owns the area where the call was heard, making it difficult for scientists to obtain permission to search for the bat, biologist Stuart Parsons said. So the greater short-tailed bat's future is still in the dark—at least for now.

Published December 6, 2010

5. Baiji

Photograph from Oxford Scientific/Photolibrary

China's baiji, or Yangtze River dolphin, may already be extinct—just 13 were found during a population survey between 1997 and 1999.

Baiji are often caught in nets, struck by boats, or killed by pollution in the industry-choked Yangtze. Authorities have placed restrictions on fishing and dumping in the river, according to ZSL, but those restrictions are widely ignored.

ZSL's Waterman said that a colleague's extensive 2006 survey turned up no dolphins, which "left him absolutely convinced that there are no animals left." However, at least one baiji sighting was confirmed in 2007. (Related: "'Extinct' River Dolphin Spotted in China.")

Overall, the IUCN "tends to err on the side of caution," Waterman added, so the baiji remains listed as critically endangered.

Published December 6, 2010

6. Mountain Pygmy Possum

Photograph by Jason Edwards, National Geographic

Ski resorts in southeastern Australia have caused the decline of the mountain pygmy possum, according to EDGE experts.

That's because grooming snow on ski slopes can disturb the snow-hibernating creatures or destroy their habitat. Thought to be extinct until one was found inside a ski chalet in 1966, the possum's range is now confined to just a few square kilometers.

(Also see "New Giant Rat, Pygmy Possum Discovered.")

Published December 6, 2010

7-8. Hispaniolan and Cuban Solenodons

Photograph by Gregory Guida, Press Association/AP

This may look like a rodent of unusual size, but the rare Hispaniolan solenodon (pictured in 2009) isn't a rodent at all.

More closely related to shrews and moles, the solenodons are the only mammals that inject prey with venom, through special grooves in their teeth. There are only two species: the Hispaniolan solenodon—native to the island of Hispaniola, shared by Haiti and the Dominican Republic—and the Cuban solenodon, which was rediscovered in 2003.

(See video: "Venomous 'Giant Shrew' Caught on Film.")

Until the introduction of predators such as dogs, cats, and mongooses to their island habitats, the "slow and clumsy" solenodons had no natural enemies, according to EDGE.

Published December 6, 2010

9. Riverine Rabbit

Photograph by Tony Camacho, Images of Africa

The riverine rabbit (pictured in a file photo) is unlike most of its kin in one crucial way: It doesn't breed like a rabbit.

While many rabbit species can raise up to 12 babies per litter and bear multiple litters in a season, the riverine rabbit usually raises one kit at a time—and it lives for just three or four years in the wild.

Furthermore, the animal is "very dependent on the thick vegetation and soft soil" found only along riverbanks in South Africa's Karoo Desert, said Vicky Nel of South Africa's Endangered Wildlife Trust. (Related blog: "South Africa's Karoo Heartland Discovered.")

Commercial farming has caused trouble for the species for many years, she added. "Either farmers plow the area—because the only arable land in the Karoo is along the river—or there is overgrazing."

Published December 6, 2010

10-11: Sumatran and Black Rhinoceros

Photograph by Joel Sartore, National Geographic

The fast decline of Southeast Asia's Sumatran rhinoceros (pictured, a mother and her calf at the Cincinnati Zoo) and the black rhinoceroses of central and southern Africa have landed the species near the top of the EGDE list.

All rhinoceros species are considered to be threatened or vulnerable by IUCN due mostly to poaching, which has doubled in the past year, according to Rick Schwartz, an information "ambassador" and keeper for the San Diego Zoo.

(Watch a video of the rare Sumatran rhinoceros in the wild.)

Compounding the issue, rhinoceroses prefer different breeding environments than many mammals.

"You can't just put a boy and a girl together and make more," Schwartz said. "The girls need girlfriends. They need a cohesive female herd, and then your top female in the herd will breed and raise her young, surrounded by her friends."

Published December 6, 2010

12. Northern Hairy-Nosed Wombat

Photograph by Jason Edwards, National Geographic

A northern hairy-nosed wombat peers out of a trap in Queensland, Australia, in a file picture. Only three known species of wombat exist, making the family one of the most evolutionarily unique. (See "Ancient Giant Wombat Sex Differences Were Huge.")

For instance, unlike koalas or kangaroos, the burrowing marsupials carry their young in pouches that face backward, which keeps dirt out. (See a picture of a common wombat.)

Predators introduced to Australia, such as the dingo, have nearly wiped out Earth's biggest wombat species. Today, only one colony of fewer than a hundred individuals remains—protected by a dingo-proof fence.

Published December 6, 2010

13. Bactrian Camel

Photograph by David Edwards, National Geographic

The Bactrian camel (pictured, a herd in the Gobi) is distinguished from the more familiar Arabian (dromedary) camel by its two humps. The species has lost out in a competition for food and water with livestock, including its own domesticated brethren. Likewise, interbreeding with the domesticated species may wipe out the wild camel for good, experts say.

(See "Wild Bactrian Camels Critically Endangered, Group Says.")

"We have a lot of camels on the planet, but if you look at the wild ones, they're critically endangered," said the San Diego Zoo's Schwartz. "It's hard for people to understand, because they say, I see camels everywhere."

The wild Bactrian also has unique adaptations to its extreme climate: Its coat goes from incredibly thick in winter to almost hairless in summer, and the animal has squishy foot pads—like "bags filled with slime"—that act like snowshoes, to keep it from sinking into the desert sand, Schwartz said.

Published December 6, 2010

14. Javan Rhinoceros

Photograph by Mary Plage, Photolibrary/Getty Images

Considered "more primitive" than Africa's white or black rhinoceroses, the Javan rhino (shown in a file photo) is the rarest of all living rhinoceros species, according to the San Diego Zoo's Schwartz.

Though the approximately 50 remaining Javan rhinoceroses live inside protected national parks in Vietnam and Java, Indonesia, the risk of poaching for their horns remains."What's really unfortunate is this horn is keratin, the same as our fingernails and hair"—and thus not very valuable, Schwartz said.

(Read related blog post: "Rhino Horn: All Myth, No Medicine.")

The two Javan rhino colonies are also at risk of disease. Earlier this year, the International Rhino Foundation discovered three dead Javan rhinoceroses with their horns intact, suggesting that the animals had died of different causes. In the past, domestic livestock have spread diseases to the rhinos, according to the foundation.

Published December 6, 2010