Facts: the extinction files

New Internationalist, March, 1997

There are between 5 and 30 million species of flora and fauna. The bulk exist in the tropics -- ten one-hectare plots of Borneo rain forest (below) can contain as many species of trees as all of North America. But we are destroying habitat and the biodiversity it sustains at between 1,000 and 10,000 times the rate of extinction before human intervention. Here are some of the better-known species we have driven to the edge of oblivion.

Beluga Whale (1)

Delphinapterus leucas

Habitat: One of the smallest whales, 4-6 metres long, with adults easily identified by creamy-white skin. Arctic Belugas are threatened (Hudson Bay) or endangered (Ungava Bay) but those in Quebec's St Lawrence River are most in peril.

Numbers: A century ago there were 5,000 St Lawrence Belugas. Today's population of approximately 500 is dangerously low.

Threat: Habitat destruction and reduced food stocks derive from hydroelectric projects and commercial fishing, toxins from boating, extensive dredging, municipal sewage and industrial waste. High concentrations of chemicals and heavy metals have been found in Beluga carcasses since 1982.

Conservation: Hunting was banned in 1979 but pollution remains a grave threat despite a clean-up launched in 1988. St Lawrence Beluga numbers may be too low to recover.

Mountain Gorilla (2)

Gorilla gorilla berengei

Habitat: All three subspecies of gorillas are threatened, but none as perilously as mountain gorillas which live in the Virunga volcanoes region of Rwanda, Uganda and Zaire. The largest living primate, it is thought to be the most intelligent land animal next to humans. Infant-mortality rates average about 45%.

Numbers: Estimated at less than 400 surviving in the wild.

Threat: The gorilla was first endangered when it was hunted for food. Currently the most serious threat is habitat destruction from human encroachment. Political unrest threatens conservation projects.

Conservation: Trade restrictions have diminished hunting for capture, but laws control rather than prohibit trade in wild gorillas. The Bwindi Forest Reserve in Uganda protects gorillas and their habitat.

South American River Turtle (2)

Podocnemis expansa

Habitat: This large, freshwater omnivore weighs approximately 50 kgs and prefers large rivers, flooded forest and oxbow lakes. Nesting occurs on sandbars or low, sandy beaches. It is found mainly in the Amazon and Orinoco basins.

Numbers: Unknown, but listed as endangered by the International Union for the Conservation of Nature.

Threat: Exploited by European colonizers for oil. Currently threatened by human encroachment in forests, floodplain clearing and dam construction. It is still hunted for eggs and meat.

Conservation: Some nesting sites are protected, but enforcement is ineffective. With proper management it could be a low-cost renewable food source in northern South America.

Chinese Alligator (2)

Alligator sinensis

Habitat: This small alligator lives in the wetlands of Anhui (lower Yangzi valley), Zhejiang and Jiangsu Provinces of China. A semi-aquatic reptile, it eats mainly snails, freshwater mussels, fish, insects and small mammals. It hibernates in the winter in burrows in the damp earth.

Numbers: Estimated at 500 in the wild. But there are many more in captive populations.

Threat: Habitat destruction and intentional extermination by expanding human populations. During the flood season many alligators drown while hibernating. Severe drought destroys their wetland homes.

Conservation: Protected by the Chinese Government. There are alligator-rearing centres in Anhui and outside China.

Siberian Crane (2)

Grus leucogeranus

Habitat: The range of these long pink-legged cranes with snow-white bodies includes: Afghanistan, China, India, Iran, Pakistan, Russia and sometimes Mongolia. Its two spring breeding areas are in the marsh-like terrain of Northern Siberia. Cranes migrate in winter to freshwater wetlands and shallow ponds. Both parents incubate two eggs but usually only one chick reaches adulthood.

Numbers: Three known flocks. The largest numbers about 2,700 birds; the smallest is 6.

Threat: The hunting of cranes on their migratory route in Iran and Afghanistan, and wetland destruction.

Conservation: Eggs laid in captivity hatched in electric incubators at nesting grounds near the Ob River. Chicks are reared by caregivers disguised with hand-puppets and crane costumes.

Peregrine Falcon (4)

Falco peregrinus anatum (North American)

Habitat: Nests on cliffs, buildings and bridges across continental North America. Numerous subspecies worldwide include the Eurasian peregrine. It hunts in grasslands, meadows and open countryside, as far as 11 kms from its nest. It can fly faster than 96 kms an hour and dive at up to 300 kms an hour to seize prey in its powerful talons.

Numbers: About 500 breeding pairs (100 in eastern North America and 400 in the west).

Threat: DDT and other organochlorine pesticides. At the top of the food chain, all raptors (birds of prey) are highly susceptible to chemical toxins, resulting in egg-shell thinning and breakage.