Legacy of extinction

Each evening in Curaa, Brazil, when a small sapphire-blue and gray parrot flies overhead to roost for the night, local residents cheer. He is the last of his kind in the wild.

Driven to the brink of extinction by smugglers, the Spix's Macaw is coveted not only for its beauty but for its rarity. Now, with only one wild bird remaining, the long-tailed parrot has become a reminder of how fragile a species can be.

Humans have been altering the environment for millenniums: Many scientists hold that early man was at least partially responsible for the demise of the woolly mammoth. Conserving and protecting endangered species, however, is a relatively new concept. Laws and regulations to protect plants and animals were not passed until the second half of the 20th century.

In the United States, the first endangered species legislation was not passed until 1967. The first international treaty, the Convention on International Trade in Endangered Species (CITES), soon followed. Yet in the past few hundred years, humans have begun destroying not only individual species but entire habitats. According to Susan Lieberman of the US Fish and Wildlife Services International Affairs program, as far as endangered species go, "the previous 900 years were not nearly as bad as the last 100."

Today, the planet is experiencing the largest mass extinction since the dinosaurs disappeared. Scientists estimate that, on average, one species disappears every 15 minutes. The main causes are human development, pollution, hunting, and the introduction of exotic species that outcompete native species.

The solutions are a bit trickier: Sometimes they work, sometimes they don't. One of the most lauded successes in the US is the bald eagle. Threatened by habitat loss, hunting, and DDT poisoning, the country's national emblem hovered on the verge of extinction in the lower 48 states in 1963, with only 417 nesting pairs.

In 1967, the country declared the bird an endangered species, making it illegal to hunt. By 1998, lack of hunting, the ban on DDT, and a captive-breeding program had allowed eagle populations in the contiguous US to climb to almost 5,800 nesting pairs.

Another species edging back from the brink of extinction is the African rhinoceros, whose coveted horn is used primarily in traditional Chinese medicine. Hunters nearly decimated the rhino populations to fill the high demand. In some countries, with the cooperation of local communities, rhino populations are rebounding at an incredible pace - there are now more than 10,000 southern white rhinos, up from less than 100 at the beginning of the century.

In other countries, rhino populations are still dwindling. Killing a rhino is now against the law, but because there is still a high-paying outlet in the black market for powdered rhino horn, the threat to rhino populations is very real. International treaties like CITES can prompt countries to institute laws, but the countries do not always have the money or strength to enforce them.

Additionally, species affected by human development can become so fragile that they are more susceptible to other dangers. The heath hen, for example, a relative of the prairie chicken, was once abundant on the East Coast of the US. But early colonists hunted the bird for food and used its habitat for farmland. By 1870, they had reduced the hen to a single population, which lived on an island off the coast of Massachusetts.

In 1908, realizing the bird was close to extinction, people established a refuge to protect the remaining 50 birds. The population thrived, and seven years later was 2,000-strong. But the next few years brought first fire, then predators, then disease. By 1932, the species was gone.

This, says M.A. Sanjayan, the director of conservation science for the Nature Conservancy in California, is why waiting until a species is endangered before protecting it is rarely effective.

"There's not one thing that creates extinction," says Dr. Sanjayan. And once the population has dwindled, he says, these factors can combine in a vortex to wipe the species out. "It's much better to think proactively when you think about population decline."

Saving one species at a time is like refusing to see the forest through the trees, says Steve Osofsky, the director for species conservation at the World Wildlife Fund. The best way to save the majority of endangered species, he says, is to protect their habitats.

(c) Copyright 2000. The Christian Science Publishing Society