Stopping the Flight To Extinction
Worldwide efforts are needed to save birds, since so many declining species are intercontinental travelers
IN a few weeks, millions of intercontinental migrants will begin appearing in the northern latitudes. Colorfully plumed and with stout hearts, they will have come hundreds - in many cases thousands - of miles to breed and nest. And for those touched by their beauty and unique ability to leave Earth's bounds at will, these spring and summer visitors will provide considerable enjoyment and inspiration.Skip to next paragraph
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But populations of once-abundant birds have been declining steadily, and some now face the possibility of extinction. Amateur bird watchers have suspected as much for 10 or 20 years, but experts now confirm unofficial reports from the field.
``Increasingly now, we have the real data to back up those anecdotal observations,'' says Stan Senner, director of the National Audubon Society's migratory-bird conservation program.
According to the United States Fish and Wildlife Service, 70 percent of all neotropical bird species that summer in the eastern United States have declined over the past decade. (Between 300 and 400 species of neotropical migrants spend the winter in Central and South America, Mexico, and the Caribbean then head north to the US and Canada.)
The number of cerulean warblers has been dropping about 3 percent a year; olive-sided flycatchers, nearly 4 percent a year; yellow-billed cuckoos, 1.5 percent a year. Rose-breasted grosbeaks have declined by more than 40 percent overall; blackpoll warblers by 60 percent.
``It's hard to believe all these favorite birds could be declining,'' says Peter Stangel, director of the neotropical bird program at the National Fish and Wildlife Foundation in Washington, D.C.
The news from the Midwest is troubling as well. Last June, the Fish and Wildlife Service reported that seven of the 12 bird species considered endemic to the Great Plains grasslands have declined over the past 25 years, with ``statistically significant'' dropoffs for the mountain plover, Franklin's gull, Cassin's sparrow, and lark bunting.
And in the Western US, the northern spotted owl has become a household familiarity, joined recently in the news by the marbled murrelet and the gnatcatcher as species threatened by industrial forestry or housing development. The number of native Hawaiian bird species has dropped by half (from 140 to 70) since Polynesians first arrived in the islands. Nobody has seen a Molokai thrush since 1988.
Edward O. Wilson, a Harvard University professor of science and an expert on the decline of species, estimates that 1/5 of bird species worldwide have gone extinct. ``Thus instead of 9,040 species alive today, there probably would have been about 11,000 species if left alone,'' he writes in his 1992 book ``The Diversity of Life'' (Harvard University Press).
Professor Wilson notes a study by the International Council for Bird Preservation (now known as Bird Life International) showing that 11 percent or 1,029 of the surviving species are endangered.
There are many reasons for the decline in bird populations. The World Wildlife Fund reported last month that some 500 species of birds are being traded in Southeast Asia, many in violation of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
``The wild bird trade has been estimated to involve somewhere between two and five million specimens per year and the largely undocumented trade in Chinese song birds, mainly to East and Southeast Asian destinations, may add another one to three million birds to the total,'' states the report, titled ``Sold for a Song.''
``No one realized until now the enormity of this trade,'' says Ginette Hemley, who heads the World Wildlife Fund's trade monitoring arm. More than 600,000 live parrots are traded every year, according to the World Resources Institute, most of those to the US.
Loss of environment cited
Domestic cats (and pets that have gone wild) are estimated to kill hundreds of millions of birds each year. Over-hunting continues in some countries. Environmental disasters like the Exxon Valdez oil spill in Alaska and the Gulf war kill hundreds of thousands (perhaps millions) of birds as well.
But the main source of bird declines is the loss of habitat.
Cutting and burning rain forests in Central and South America for timber and cattle ranches, plowing up prairies to produce grain in the North American Midwest, urban sprawl and industrial development, draining wetlands, the fragmenting of forests all over the world, damming and diverting rivers, acid rain, and toxic runoff from mining and farm chemicals - all have contributed to the degradation and destruction of bird habitats.