Migratory Birds are Gauges of Global Biodiversity - and Their Numbers are Plummeting Alison Fairbrother - TakePart
go to original December 26, 2012

While migratory birds are somewhat adaptable to changes in temperature, the compounding impacts of climate change have begun throwing them for a loop. (Luke MacGregor/Reuters)

Nearly 10,000 kinds of birds fly, sing, and nest around the world, but an alarming 12 percent of them are classified as globally threatened or critically endangered. The natural rate of extinction for birds is one bird per century. In the last 30 years, 21 bird species have disappeared.

The numbers of migratory birds in particular - those that undertake seasonal journeys across hundreds or thousands of miles from breeding areas to wintering grounds - are nose-diving.

Tar Sands Development

More than 300 species of birds - including the common loon, the whooping crane, and the white-throated sparrow - roost in Canada’s Boreal Forest several months of the year. But tar sands oil development threatens the survival of the forest’s resources and the migratory birds that depend on them.

A report by the Natural Resources Defense Council found that if all the tar sands development projects currently proposed were completed, 166 million migratory birds would perish over the next 50 years. “Virtually every facet of tar sands oil development has the potential to harm migratory birds,” the report states, including strip mining of forests, the creation of tailing ponds that store toxic materials used in the tar sands extraction process, and air and water pollution that decimates wetlands and reservoirs.

If tar sands development continues apace, we can expect more sad stories like this one: In 2008, 500 ducks landed in an oil company’s pollutant-filled tailing pond in Alberta, Canada, thinking it was a safe place to take a quick swim. Pretty soon, hundreds of decomposing ducks floated on the surface of the water - only three ducks survived the ordeal.

Climate Change

While migratory birds are somewhat adaptable to changes in temperature, the compounding impacts of climate change have begun throwing them for a loop.

An analysis by the Audubon Society over four decades shows that many species that normally winter in the United States are moving farther north - evidence that they are being affected by climate change and rising winter temperatures. The purple finch, for example, a favorite at backyard bird feeders, has undertaken a northward movement of 433 miles over the course of the last 40 years in response to shifts in temperature. Check out the Audubon Society’s map of the most dramatic northward shifts.

The life cycles of migratory birds are tied to seasonal changes in light, rather than climate. Because of the effects of climate change on local vegetation and insect hatching, long-distance migratory birds may begin arriving at their destinations too late to find food, according to the Natural Resources Defense Council.

Poisoning

Blackbirds have historically been considered “crop pests,” and have been subject to poisoning and other massive eradication campaigns in the southern United States. In 2009, according to the Christian Science Monitor, the U.S. Department of Agriculture euthanized more than 4 million red-winged blackbirds, starlings, cowbird, and grackles. A bird control program began in the 1960s under the sinister name “Bye Bye Blackbird,” and has persisted for decades. Information about the program’s activities was made public in 2009. The Monitor reported that most of the birds were euthanized with common pesticides that the government maintains are not harmful to humans or pets.

The gorgeous rusty blackbird - so named for the rust-colored hue of its feathers and its song, which sounds like the swinging of a rusty gate - has declined between 85 and 99 percent since the 1960s. The rusty blackbird often roosts with more common species, making it a prime target for pesticide exposure.

Fishing Nets

Bird “bycatch” in fishing nets has increased in recent years, which is particularly worrisome, because seabirds are declining faster than any other group of birds. More than two million seabirds have perished in the nets of European fishing vessels in the last decade, according to Bird Life International. Some species of seabirds are susceptible to hook and line fishing; others are caught in trawls or drowned in gillnets.

Another concern are the ravenous, invasive rats that have made their way onto ocean islands, and are now preying on a quarter of all species, eating chicks and eggs and decimating populations.

Whether due to rat attacks or fishing gear, nearly half of all seabird species are experiencing population declines. The majestic albatross family of birds is in serious trouble - 17 of the 22 species of albatross are at risk for extinction.

Loss of Stopover Habitat

On a typical migratory journey, birds need to land, rest, and refuel. The Gulf of Mexico and the Great Lakes present two huge barriers for migrating birds en route from northern nesting areas to their wintering grounds in the southern U.S., Mexico, and Central and South America. The Nature Conservancy estimates that hundreds of millions of birds make the 600-mile trip across the Gulf of Mexico each year. Some birds, like the American golden plover, can fly for 48 continuous hours!

But erosion of the Gulf wetlands and the loss or fragmentation of coastal stopover grounds to property development has had a major impact on the availability of food sources and places to rest. Increasingly, conservationists are recommending that property owners plant native vegetations in their yards, to provide micro-habitats for migrating birds. The Audubon Society has launched a program that will turn parks, gardens, and backyards into stopover grounds that millions of birds may use as refuges on their long, arduous journeys.

We invite you to add your charity or supporting organizations' news stories and coming events to PVAngels so we can share them with the world. Do it now!