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Humans Are Driving Birds to Extinction, Group Warns

James Owen in England
for National Geographic News
May 16, 2003
 
Conservationists warn that many birds face the same fate as their prehistoric ancestors, the dinosaurs. But it isn't an asteroid or volcanic eruption that's threatening to finish them off. The culprit, they say, stares at us from the bathroom mirror every day.

Humans are singled out in a recent report as the cause of what many scientists believe is the biggest mass extinction of animals in 65 million years. Published by the Worldwatch Institute, a U.S.-based environmental research organization, the report says scientists' fears are backed up by plummeting bird populations.

In the last two centuries over 100 bird species have disappeared. Another 1,200—12 percent of the planet's total—face extinction this century, according to BirdLife International, a worldwide conservation organization.


Worldwatch researcher Howard Youth, author of the report, says human factors are central to declining bird life. These include human encroachment on bird habitat, invasions by alien plant and animal species introduced or transported unwittingly by humans, hunting, and climate change wrought by human activities. And like canaries down the coal mine, he says, birds act as a crucial early-warning system that should alert us to the vulnerability of other plants and animals.

"People have long been inspired by the beauty, song, and varied behavior of birds," he said. "Today, we also recognize that birds provide critical goods and services in their habits, including seed dispersal, insect and rodent control, scavenging, and pollination.

"In addition, many bird species are valuable environmental indicators, warning us of impending environmental problems."

The report identifies habitat loss as having the most serious impact on bird life.

Youth says deforestation rates of between 50,000 and 170,000 square kilometers (roughly 20,000 to 65,000 square miles, or from slightly smaller than West Virginia to larger than Florida) per year are putting 85 percent of the world's most threatened bird species at risk.

Agriculture is also blamed. Almost half the land area of Europe is now farmed, much of it intensively. Youth says modern farming methods limit nesting opportunities, remove cover, and reduce food availability.

Bustard Decline

Europe's most prominent victim is its largest bird, the great bustard.

In the 18th century, Englishman Oliver Goldsmith wrote: "It was once much more numerous than at present; but the increased cultivation of the country, and the extreme delicacy of its flesh, has greatly thinned the species; so that a time may come when it may be doubted whether ever so large a bird was bred among us."

His gloomy prediction proved accurate. By the mid 19th century the great bustard was extinct in Britain. In the rest of Europe its distribution is greatly diminished.

The disappearance of native birds is often heralded by the arrival of alien animals, says Youth.

The dangers of such introductions—both deliberate and accidental—are evident on remote islands. Having evolved over hundreds of thousands of years to suit the conditions of their isolated homes, many island birds are ill-equipped to cope with outsider competitors or predators.

For instance, Hawaii's endemic bird species are being put to flight by a variety of invaders, including cats, rats, feral pigs, and mongoose.

On St. Lucia, the small Indian mongoose was brought in to deal with an earlier influx of rats. Unfortunately, the mongoose also developed a taste for the white-breasted thrasher—one of the Caribbean's most endangered birds.

The mammal was also introduced to control rats on Mauritius in the Indian Ocean—once home to the famous dodo. This strange, flightless pigeon epitomized the problems faced by endemic island species. Waddling was no defense against hungry sailors.

Meat-eating, acid-spitting yellow crazy ants have imperiled the Christmas Island hawk-owl and Abbot's booby. The birds are found only on Christmas Island. The Australian government has been scattering poisoned bait from helicopters to keep the ants at bay.

Introduced birds can be just as dangerous. A massive cull of ruddy ducks is about to begin in Europe in an effort to save Spain's white-headed duck.

The ruddy duck, a native of North America, is now interbreeding with its close relative. Conservationists say the white-headed duck will soon be wiped out if drastic action isn't taken to stop the sexually precocious invader.

Unnatural Situation

"The tragedy of this situation is that the ducks themselves are not to blame," said a spokesman for the Royal Society for the Protection of Birds in Britain. "They are doing what comes naturally to them, having been placed in an unnatural situation by the actions of humans."

Youth says similar actions mean many other birds are living on the brink. He says more than 20 localized pheasant species in Asia are endangered by over-hunting. And almost a third of the world's 330 parrots are facing extinction following habitat loss and trapping for the pet trade.

Conservationists say unregulated fisheries in the southern oceans are endangering the albatross. Thousands of birds are being hooked and drowned on baited longlines set for fish.

Richard Thomas, communications manager for BirdLife International, said: "Of the 21 albatross species recognized by BirdLife [some say 24 species], 17 are currently considered at risk of global extinction due to longline fisheries."

Global warming—widely regarded as a manmade phenomenon—also looks set to become a key factor in determining the plight of many species.

In Britain, for instance, temperatures are estimated to rise by as much as 2.6 degrees Celsius (4.7 degrees Fahrenheit) in the next 50 years. If they do, the capercaillie—the world's largest grouse—is predicted to lose 99 percent of its pine forest habitat.

In North America, the Arctic tundra is expected to retreat northwards and be replaced by forest. The globally threatened spoon-billed sandpiper could lose 60 percent of its nesting sites.

Youth says conservation efforts must take account of man's impact on the wider environment, instead of focusing on isolated wildlife reserves. Isolation means vulnerability—as the dodo's story proves.

Youth concludes: "Birds provide us with food, inspiration, a link to nature, and an alert system for detecting environmental ills, but today, this feathered resource is in great need of attention."

More Bird Stories by National Geographic News:
Tall As a Deer, Huge U.K. Bird Staging a Comeback
Memory Aids Birds in Migration, Study Finds
Crows Better at Tool Building Than Chimps, Study Says
Extinction Near for Albatross, Experts Warn
51-Year-Old Albatross Breaks N. American Age Record
Are Flashy Male Birds Threats to Their Own Species?
Wild and Escaped Parakeets Captivating City Dwellers
Bright Beaks Signal Health to Female Birds, Study Says
Coot Birds Can Count, Study Says
Falconry Used to Secure North American Airports
Cuckoos, Wrens in Escalating Evolutionary Arms Race
Deer Behind Britain's Great Bird Decline?
"Mysterious Plague" Spurs India Vulture Die-Off
Gamblers Fuel Trade in "Lucky" Vulture Heads in Africa
Ospreys Flock to Cuba, With Conservationists Close By


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