Prairie Wanderings: Birds and global warming
The past decade has been the warmest on record according to meteorologists. Earth's average surface temperature during most of the 10,000 years since the Ice Age has varied less than 2 F degrees. From the year 1500 to 1900, the average temperature rose about 0.9 F degree; from 1900 to the present, it rose another 1.8 F degrees.
The Intergovernmental Panel on Climate Change, composed of more than 1,000 meteorology specialists, affirmed that global warming is caused mostly by the greenhouse gases carbon dioxide, methane, and nitrous oxide due to industrial activity and the cutting and burning of forests. Advanced computer projections indicate that, if nothing is done to halt current trends, the global average surface temperature will continue to rise from 2.5 to 10.4 F degrees by 2100.
In the last few years, we've seen armadillos ranging farther north from Oklahoma into Kansas. And birds are moving northward. Three decades of data published last spring indicate that a dozen British bird species have already shifted their ranges an average of 12 miles north during the past 20 years. In North America, the summer distributions of many migrating birds are also shifting northward. The center of the golden-winged warbler's breeding ground around the Great Lakes and along the Allegheny Mountains has moved nearly 100 miles northward during the past 20 years.
We also see changes in the timing of bird migration and breeding. Already, many European and North American species are migrating nine days sooner and breeding 10 days earlier than they did 30 years ago. A long-term study in Michigan found that 15 spring migrants were arriving 21 days sooner in 1994 than they did 29 years earlier.
Of course climate changes also affect the habitats of birds. Native forests are likely to shift northward to be replaced by southern species. Changes in rainfall patterns could see deserts converted into grasslands or grasslands into deserts.
Global warming could also raise the sea level, inundating coastal marshes and beaches destroying habitats of shorebirds and waterfowl. Droughts in the northern prairies could dry up lakes, rivers, marshes, and wetlands such as Cheyenne Bottoms.
Would these changes matter? It is obvious that a shifting range can challenge the relocating bird population with new prey, new predators, and new competitors in addition to new, perhaps less describable, habitats.
And what if a bird species' earlier migration and reproduction are out of sync with its food supply? In the Colorado Rockies, robins are leaving their low-altitude wintering grounds about two weeks earlier than they did in the late 1970s, an apparent response to warming temperature. When they reach their mountain top nesting grounds, it is still winter, and they must wait for snow to melt before they can find food for themselves and their young.
Some birds require very specific plants for food. The endangered red-cockaded woodpecker in southeastern United States depends on the mature pine forest for habitat. If the bird shifts northward to follow the cooler climate, it can't want for mature pines to grow in the new location. Could it adapt to other trees?
In forests of northeastern U.S., several species of wood warblers prey on the eastern spruce budworms which, in turn, devour the leaves of millions of acres of timber each year. In normal conditions, these warblers consume more than 80 percent of the budworm's larvae and pupae. If the warblers move northward, what would happen to the forest?
Birds currently common in the summers of south central Kansas and that could soon become scarce include black-capped chickadees, white-breasted nuthatches, house wrens, gray catbirds, rose-breasted grossbeaks, several sparrows, Baltimore orioles, and American goldfinches. Summer ranges of purple martins, eastern bluebirds, and brown thrashers might contract in Kansas. We could see more western kingbirds, scissor-tailed flycatchers, and Bell's vireos. For more complete lists, see www.nwf.org/ climate/statemigratorybirds.html.
Les Line, field editor of National Wildlife, says the tragedy of all this is that the "actions needed to slow global warming already are well known: reduce emissions of carbon dioxide and other greenhouse gases from fossil fuel-burning power plants, factories and automobiles. Yet the world's industrial nations — mostly the United States, the planet's biggest pollutor — have so far done very little to solve the problem. Recently, the Bush administration [finally] acknowledged that continued buildup of greenhouse gases would damage wildlife and ecosystems, yet it did not endorse any meaningful steps to reduce pollution.
President Mark Van Putten of the National Wildlife Federation continued: "How can it [the administration] acknowledge a disaster in the making and then refuse to solve the problem, especially when solutions are so clear?"
