From field sparrows to boreal chickadees, 20 of the most common species in North America are being decimated, report warns
Globe and Mail, September 23, 2008 at 4:27 AM EDT
There has been a precipitous decline of more than 50 per cent in the populations of 20 of the most common North American birds over the past four decades, alarming conservationists, who say the trend is an indicator of a serious deterioration in the environment.
The figures were in the State of the World's Birds, a report released yesterday and posted on a related website. Canadian and U.S. figures showing the decline were based in part on the annual Christmas bird counts compiled by thousands of volunteers across North America, and on a separate breeding bird survey.
The species in trouble include those that breed in Canada's boreal forest, such as the evening grosbeak, greater scaup, rusty blackbird and boreal chickadee. Also, many grassland species are listed, including the eastern meadowlark, loggerhead shrike and field sparrow.
The drop has also extended to the avian marathon fliers, those birds that migrate from North America to tropical and subtropical designations in Latin America each year. More than half of these migrating species have experienced population declines, including the Canada warbler and bobolink.
The sharp declines for many of the most common but lesser known birds comes as some iconic North American species, including bald eagles, whooping cranes and peregrine falcons, are making strong comebacks. The eagle and falcon populations are recovering due to bans on toxic pesticides, and while it isn't known exactly why all of the other species are declining, alterations in habitat are usually the prime suspect.
"Though there is much we still need to learn about what is driving the declines, loss and degradation of habitat are usually implicated," said Jon McCracken, a spokesman for Bird Studies Canada, a conservation group in Port Rowan, Ont., that took part in the global survey.
"It is particularly worrying when we find that some of our most common species are headed into trouble."
The alarming trend found in North America is also occurring elsewhere, according to the report which was issued by Birdlife International, a global umbrella group of environmental organizations.
The report said that the status of the world's birds - 9,856 living species is the current count - "continues to get worse" and the "deterioration is accelerating, not slowing." Of these species, more than 1,200 are thought to be in trouble. The most threatened are albatrosses (82 per cent of species are at risk), cranes (60 per cent at risk) and parrots (27 per cent at risk).
"Alarm calls from the world's birds are becoming ever louder ...," the report said.
A total of 153 bird species are thought to have become extinct since 1500, including 18 from 1975 to 1999 and another three known or suspected to have died out since 2000. The rate of species extinctions is "exceptionally high," about 1,000 to 10,000 times what would occur in nature over these time periods.
Among the threats to populations are the replacing of natural forests with plantations of only one or two tree species, the biofuel mania that is leading to forests being converted for palm-oil production, logging, industrial agriculture and fishing, and the spread of invasive predators such as rats.
Conservationists have identified about 10,000 places in the world that offer crucial habitat for birds. Of these, about 600 are in Canada. They include hot spots such as Point Pelee National Park on Lake Erie, Toronto's Leslie Street Spit, a man-made peninsula that is one of the largest breeding areas on the Great Lakes for colonial water birds, and Boundary Bay, an area near Vancouver that is an important stopover site for migratory birds on the Pacific coast.
Only about half the important birding sites in Canada are protected by the federal, provincial or territorial governments. "We've got to make sure we have a strategy to protect all of them," said Sarah Wren, a biologist with Nature Canada, an Ottawa-based conservation group that also worked on the bird counts.
Birds have evolved to thrive in some of the world's most forbidding environments, but they're facing a huge challenge coping with humans. One in eight bird species around the world is at risk of extinction, with habitat loss and degradation the main reason. In North America, many common species have experienced population declines of 50 per cent since the 1960s.
Spix's Macaw from Brazil became extinct in the wild in 2000.
Hawaiian Crow became extinct in the wild in 2002.
GLOBALLY THREATENED SPECIES
Extinct in wild: 4
Critically Endangered: 190
IMPORTANT BIRD AREAS OF THE WORLD
NEARCTIC 732 species
PALEARCTIC 937 species
NEOTROPICAL 3,370 species
INDOMALAYAN 1,700 species
OCEANIC 187 species
AFROTROPICAL 1,950 species
AUSTRALASIAN 1,590 species
ANTARCTIC 85 species
More than 10,000 important bird areas have been identified
SOURCE: STATE OF THE WORLD'S BIRDS (BIRD LIFE INTERNATIONAL)