WASHINGTON -- An international conservation organization says the Chesapeake and Delaware bays are among 15 "critical" migratory bird habitats around the world most threatened by global warming.
The World Wildlife Fund, in a report summarizing recent scientific research, says rising sea levels, changes in the timing of the seasons and drier weather in some locations have begun to alter breeding grounds and food availability, and could change them faster than some migratory birds can adapt.
Higher temperatures could even threaten to force the Baltimore oriole to Canada.
Jeff Price of the American Bird Conservancy said the oriole, which winters in Mexico and summers throughout the eastern United States, is already declining in Louisiana.
"It may be because it's too warm," he said, "but it also could be too many cats." If the cause is a change in climate, computer models suggest, the oriole will flee north from most of its current range -- including Baltimore -- in 50 to 75 years.
In any case, said World Wildlife Federation spokesman Lee Poston, "the first impacts of climate change can already be seen" in loss of habitat and inundation of coastal wetlands like those on the Chesapeake.
One-third of the marshes at the Blackwater National Wildlife Refuge on the Eastern Shore has been lost to rising seas levels and rapid erosion in the past 50 years, said Stephen P. Leatherman of the University of Maryland's Laboratory for Coastal Research. "Nobody knows quite how to stop it," he said.
Earlier springs around the world and longer summers in the Arctic could explain preliminary evidence of delays in the migration of the red knot, a species that refuels on the Delaware Bay.
If the flocks miss the emergence of certain insects and the bay's rich but brief bounty of horseshoe crab eggs, said Brian Harrington of the Manomet Observatory in Massachusetts, their migrations could fail and their numbers could plummet. Of 26 species of New World shorebirds studied, he said, 16 are in decline.
Poston said said such threats should encourage governments to reach binding agreements to reduce the combustion of fossil fuels, which release so-called greenhouse gases -- principally carbon dioxide -- into the atmosphere and contribute to global warming.
The Clinton administration has said that it will negotiate some form of "realistic" binding agreement on limiting such emissions. Prior U.S. policy called for voluntary limits.
