The Wildlife Conservation Society released a list of critically endangered species dubbed the "Rarest of the Rare" -- a group of animals most in danger of extinction, ranging from Cuban crocodiles to white-headed langurs in Vietnam.

The list of a dozen animals includes an eclectic collection of birds, mammals, reptiles and amphibians. Some are well known, such as the Sumatran orangutan; while others are more obscure, including vaquita, an ocean porpoise. The list appears in the 2010-1011 edition of State of the Wild -- a Global Portrait.

Threats to each species vary widely. In the case of the vaquita, fishermen's nets are catching them and inadvertently causing them to drown. Meanwhile, the Grenada dove -- the national bird of the small island nation -- has been severely impacted by habitat loss. Other species suffer from illegal trade, as in the case of the ploughshare tortoise.

"The Rarest of the Rare provides a global snapshot of some of the world's most endangered animals," said State of the Wild Kent Redford, director of the Wildlife Conservation Society Institute. "While the news is dire for some species, it also shows that conservation measures can and do protect wildlife if given the chance to work."

The list of endangered species includes:

Cuban crocodile : Currently restricted to two small areas of Cuba.

: Currently restricted to two small areas of Cuba. Grenada dove : The national bird of Grenada is threatened by habitat loss.

: The national bird of Grenada is threatened by habitat loss. Florida bonneted bat : Thought to be extinct in 2002; a small colony has since been discovered.

: Thought to be extinct in 2002; a small colony has since been discovered. Green-eyed frog : Only a few hundred of these small amphibians are left.

: Only a few hundred of these small amphibians are left. Hirola : Also called Hunter's hartebeest; the hirola is a highly threatened African antelope.

: Also called Hunter's hartebeest; the hirola is a highly threatened African antelope. Ploughshare tortoise : With only 400 left, the ploughshare tortoise is threatened by the illegal pet trade.

: With only 400 left, the ploughshare tortoise is threatened by the illegal pet trade. Island gray fox : Living on the California Channel Islands, this is the smallest fox in the United States.

: Living on the California Channel Islands, this is the smallest fox in the United States. Sumatran orangutan : This population has declined 80 percent during the past 75 years.

: This population has declined 80 percent during the past 75 years. Vaquita : This small ocean porpoise is drowning in fishing nets.

: This small ocean porpoise is drowning in fishing nets. White-headed langur: Only 59 of these monkeys remain on a small island off Vietnam.

The 2010 list highlights positive news, with two species on the road to recovery thanks to conservation efforts: Rober's tree frog whose population has grown due to captive breeding in zoos; and Przewalski's horse, which is starting to rebuild numbers after being re-introduced into the wild.

The 2010-2011 State of the Wild includes a special section devoted to the impact of human conflicts on wildlife and wild places. It considers how conservation can contribute to peace-building and reconstruction in post-conflict areas.