Across the globe, conservation efforts are underway—from setting aside designated nature reserves to intensively managing the recovery of an endangered species. As humanity's impact has spread from the Arctic to the Amazon, stewardship of natural resources—and wildlife—has grown, and has become vital to the future of Earth's biodiversity. Yet, few studies have shown whether such conservation works. Now three new studies in Science demonstrate how such guardianship delivers in Europe and the Americas.

European Birders, Rejoice!

In April 1979 the member governments of the European Community (E.C.) launched the Bird Directive. The bureaucratic name conceals a broad effort to help threatened avians recover in their natural habitat (hence a subsequent E.C. Habitat Directive in 1992). Now a new analysis by biologists, statisticians and birders reveals that the two directives have worked exactly as intended.

First and foremost, the most threatened birds on the list—including several species of falcons and divers as well as the Slavonian grebe, Eurasian bittern and barnacle goose—did better once listed than those species that were not. These birds also did better in the member states than those outside the union. And the birds did best of all in those countries that aggressively employed special protection for their habitats.

"For the first time, we use quantitative data to assess the success of one such agreement—the E.U. Birds Directive," says senior research biologist Paul Donald of the Royal Society to Protect Birds in the U.K., who led the analytical team. "The success of the Birds Directive gives hope that other international agreements will be successful in reducing the current extinction crisis."

Ferreting Out Success

Reduced to just seven individuals in 1987, North America's black-footed ferret (Mustela nigripes) appeared destined to disappear permanently, and not only from the wild. But a captive breeding program produced 4,800 new ferrets—albeit ones with smaller skulls and shorter limbs—and in the early 1990s, several hundred were reintroduced into the wild at 12 sites in six U.S. states and in Mexico.

At one such site, Shirley Basin in Wyoming, 228 reintroduced ferrets almost immediately suffered a catastrophic sylvatic plague as well as canine distemper. By 1997, only five ferrets survived.

But the ferrets weaseled their way out from oblivion one more time, springing back to 52 animals by 2003 and 223 animals last year. "Our results indicate that populations of the black-footed ferret have the potential to rebound very quickly under favorable conditions, even after persisting at low levels for many years," says biologist Martin Grenier of the Wyoming Fish and Game Department.

The key is the ferrets' ability to reach sexual maturity within a year. As long as they survive or reproduce in that period, their population can recover, unlike other endangered mammal carnivores such as the Florida panther that require much higher rates of adult survival.

Of course, the Shirley Basin ferrets could still be felled by another outbreak of plague, disease within the prairie dogs they feed on or simple habitat loss, but it now seems possible the species might reestablish itself in the wild, thanks to captive breeding and their own innate fecundity. "Long-term, we'd like to initiate an additional release site in Wyoming," Grenier says, "and eventually recover the species."

Peruvian Amazon Protection

Whether birds or ferrets, no animal can thrive in the wild without adequate, appropriate habitat. Saving land, particularly rainforest land with its high ratio of endemic animal species, will therefore be required. And satellite pictures of the Peruvian Amazon basin show that efforts to preserve trees there are working.

A team of Peruvian and American scientists studied satellite imagery stretching back to 1999 to map forest disturbance and destruction. Comparing those images with national land management plans—which areas were owned by indigenous tribes, which areas were protected, and which were designated for logging—revealed that the majority of the damage was confined to unprotected areas.

"Conservation lands remained well protected and underwent relatively little (1 to 2 percent) forest change," says ecologist Gregory Asner of the Carnegie Institution's Department of Global Ecology at Stanford University. "However, we also found that forests neighboring timber concessions underwent elevated levels of forest disturbance and deforestation."

The result may be simply a reflection of the remote inaccessibility of the Peruvian Amazon compared with its Brazilian counterpart. A lack of navigable rivers and roads hinders efforts to remove timber and wherever roads do go, destruction follows. But, because government reserves and indigenous owners restrict access and road building, they, in effect, protect the forest. "As roads are built, we would expect continued forest loss," Asner says, "but, at the moment, the forest is relatively intact."

The Importance of Being Conservative

As bird biologist Donald noted, the world is undergoing an extinction crisis. The litany of death proceeds apace: Three species of plant or animal disappear every hour, according to the U.N. And many more tremble on the verge of destruction, occasionally slipping over into oblivion—like the Yangtze river dolphin, or baiji.

But as these efforts show, conservation can work, whether across international borders or on a smaller scale on the Wyoming prairie. If such stewardship continues, the world need not suffer the loss of another animal like the baiji.