Green Thursday: One Quarter Of All Mammals Face Extinction

The Caspian Seal (Pusa caspica) is the smallest of the world's seals and lives only in the inland Caspian Sea in Asia. The Caspian Seal population, devastated in recent decades by wolves and by distemper virus, is further shrinking due to pollution and the loss of its habitat

At least one-quarter of the world's mammals in the wild are threatened with extinction, according to a new international survey that blames the loss of wildlife habitat, hunting and poaching for the steep declines.

A cheetah (Acinonyx jubatus) rests at the animal orphanage in Nairobi's National Park. The world's fastest land animal also faces habitat loss.

The survey, assembled over five years by 1,700 researchers in 130 countries, is the most comprehensive yet to assess the status and future of mammals on every continent and in every ocean.

The "baiji," or Chinese river dolphin, faces extinction and already might have joined the species that have vanished from Earth. Others are not far behind, such as the "vaquita," a small porpoise that is drowning in fishing nets in the northern Gulf of California; the North Atlantic right whale, and various monkeys and other primates hunted by poachers in Africa.

Scientists have determined that about one-quarter of the world's 5,487 species of mammals are threatened with extinction. The proportion of marine mammals in trouble appears to be higher, with an estimated one-third facing a serious threat of being wiped out. Many are killed when they are struck by ships or entangled in fishing gear.

The Tasmanian devil (Sacropilus harrasii), a fierce, small, dog-like marsupial, is found only on the Australian island of Tasmania. Its population has declined by more than 60 percent over the past 10 years due to a fatal infectious cancer.

About one-half of the world's remaining apes, monkeys and other primates face threats from hunting or destruction of forests to make way for farming. Chimp and gorilla meat fetches a higher price in many markets in Central African cities than beef or chicken because it's considered a luxury item.

Scientists find mammal extinction worrisome because a diversity of species stabilizes the planet. Each extinction disrupts this balance and ripples through the food chain, making it difficult for other species, including humans, to survive.

The bleak assessment was released in Barcelona at the World Conservation Congress, a meeting of 8,000 scientists, conservationists, business leaders and representatives from governmental environmental ministries. It was part of a larger update to the Red List of all threatened species maintained by the International Union for the Conservation of Nature, which hosts this gathering every four years.

The Red List has several categories, including: extinct; extinct in the wild; and threatened with extinction, including critically endangered, endangered and vulnerable.

Jonathan Baillie, director of conservation programs for the Zoological Society of London, said that a sampling shows that 24 percent of all vertebrates -- those animals with a backbone — appear to face extinction. To track the health and abundance of all species is too massive a job, Baillie said, but he suggested that such sampling might be tantamount to creating a Dow Jones industrial average index for the planet's biodiversity. In this case though, he said, "there's no 700-billion-dollar bailout on the horizon."

The Red List once was published as a book, but the endangered list has grown so long -- now 44,838 species — that it is now an online catalog at www.iucn.org/redlist.

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