Note: This article is a sidebar to this issue's feature story.
Even beyond the suburbs, crows dog their human benefactors. In the old-growth forests of the Olympic Peninsula, just across the Puget Sound from Seattle, University of Washington graduate student Erik Neatherlin has found that crows are taking full advantage of the leftovers at crowded campgrounds. Using these spots as base camps, they travel close to 20 miles into the forest, where they can prey on the eggs and young of sensitive bird species such as the endangered marbled murrelet.
"The campgrounds are steppingstones for crows," says University of Washington biologist John Marzluff. "With enough of these little points, you can cover the whole peninsula with subsidized predators."
If weekend campers - and their winged tagalongs - do such serious damage to native wildlife, what happens when humans decide to camp out in the forest for good? For the answer, you have to visit the echoes of urbanization, where rural sprawl has perforated the landscape.
Andrew Hansen, an ecology professor at Montana State University in Bozeman, works in the country's most famous ecosystem, in and around Yellowstone National Park. Hansen has found that much of the best wildlife habitat around the park has been developed in recent years. With the new human residents, he says, comes a host of problem creatures.
Cowbirds, strongly associated with human development, enthusiastically knock other birds' eggs out of the nest, depositing their own eggs to be hatched and raised by the unsuspecting parents. This "nest parasitism," along with fierce introduced predators - also known as cats and dogs - has driven many native bird species out of the warmer valleys and into less rewarding alpine habitats.
Grizzly bears are feeling the pain of rural sprawl, too: Though the grizzly population within the park is on the rise, some researchers fear an equally large decline is taking place on private lands outside the park.
Like Marzluff, Hansen says the impacts of all sorts of sprawl are long-lasting, little understood and far beyond those of familiar environmental bugaboos.
"When I go to northern Alberta, where biologists are totally focused on logging," says Hansen, "I tell them, "Count your blessings.' "
In Colorado, one of the West's fastest-growing states, wildlife biologist Richard Knight has developed similarly affectionate feelings about ranching. The Colorado State University professor recently compared wildlife and plant diversity in 93 sites, including rural subdivisions, intact ranchland and protected areas. To nearly everyone's surprise, he found that well-managed ranchland had levels of wildlife diversity equal to that of protected areas. The dissected landscapes in subdivisions came in dead last.
Knight collected more damning evidence in Pitkin County, the heart of Colorado's ski country, where local officials hired Knight and his graduate students to study the impacts of subdivisions in the Aspen area. The researchers found that most homes were surrounded by a bubble of crows, raccoons, magpies and their adaptable brethren. More sensitive native species, such as orange-crowned warblers, stayed at least 100 yards away.
"Most people think wildlife is wildlife," he says. "They don't know the difference between a robin and an orange-crowned warbler. They don't know that European starlings are exotic."
Only time and public education, says Knight, will help the new residents of the New West learn to see the subtleties - to recognize that crowds of magpies, or crows, or cowbirds are signs of a system far out of balance.