Warming climate threatens species of migratory birds

BONN

Disoriented by erratic weather, birds are changing migration habits and routes to adjust to warmer winters, disappearing feeding grounds and shrinking wetlands, a migration specialist says.

Failure to adapt risks extinction. Birds face starvation when they arrive too early or too late to find their normal diet of insects, plankton or fish. In the north, some birds have stopped migrating altogether, leaving them at risk when the next cold winter strikes.

“Species that adapted to changes over millennia are now being asked to make those adaptations extremely quickly because of the swift rise in temperatures,” said Robert Hepworth, executive secretary of the Convention on Migratory Species, a treaty under the auspices of the U.N. Environment Program.

“We don’t know how many will survive. We will lose species,” he said in an interview Saturday on the sidelines of an international climate-change conference in Bonn.

Over the weekend, bird-watchers and conservationists in dozens of countries marked World Migratory Bird Day with concerts, films and children’s drawing contests to attract attention to the rising threat of global warming.

Climate change adds another threat to bird life already under pressure from human intrusions such as coastline development.

The Intergovernmental Panel on Climate Change — a body of some 2,500 scientists — has warned in a series of reports this year that high emissions of greenhouse gases are likely to raise the Earth’s average temperatures by at least 3.6 degrees.

The warming is predicted to drive up to 30 percent of known animal species to extinction — and migrating birds are especially vulnerable.

Climate change can strike at each stage of their annual trek, from breeding ground to rest stops to their final destination.

Studies cited by the convention say arctic permafrost is melting in regions where many bird species breed. Even moderate rises in sea levels can swamp wetlands where birds stop to feed. Deserts are expanding, lengthening the distance between rests.

Mr. Hepworth recalls watching great V-formations of Bewick’s swans arriving in his native Britain from northern Russia for the summer. Fewer are seen now.

The extraordinary travels of the red knot are another example. The medium-size shorebird breeds in Siberia and migrates to southern Africa, shedding half its body weight under the strain of a flight that reaches survival limits. The expansion of the northern African deserts could push them over the edge.

The same species also breeds in Canada and migrates to wintering grounds on the southern tip of South America. In one of its publications, the Audubon Society called the red knot one of the champion long-distance migrants of the bird world. During migration along the North American coasts, the red knot is often found in huge, densely packed flocks, which makes it vulnerable to habitat degradation.