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Urban Expansion Straining Wildlife: With Growth Altering Their Habitat, Animals Struggle to Adapt to City Life

Posted on: Sunday, 5 February 2006, 12:00 CST

By Bruce Henderson, The Charlotte Observer, N.C.

Feb. 5--Growth is tilting Mecklenburg County's balance of nature, creating wildlife winners and losers.

The human footprint: A third of the tree cover toppled in two decades. Nearly three-fourths of the streams polluted.

Yet wildlife hangs tough. As anyone whose garbage has been raided by raccoons knows, many of the county's 558 known animal species get used to asphalt.

It's what you don't see that worries biologists.

Slipping away are animals -- salamanders, mussels, grassland birds -- that are early alarms of a sick environment.

"They all have their little niche," said Don Seriff, conservation supervisor in the county parks department. "If that niche isn't there, they don't survive."

Aquatic creatures, captives of degraded water, are fading fastest. Nearly 30 percent of the state's native fish, mussel and crayfish species are threatened with extinction.

Biologists divide urban wildlife into two camps. Generalists such as coyotes adapt to new foods and the clamor of city life. Specialists such as bobwhite quail, with highly specific food and shelter needs, claw for life amid their shredded habitat.

Even the animals that thrive in a homogenized world face new dangers. Evolution never prepared white-tailed deer for freeways, where they cause more N.C. wrecks than drunken drivers.

Eastern bluebirds reproduce almost as well on suburban golf courses as they do in rural hayfields, Davidson College bird behavioral ecologist Mark Stanback learned in a six-year study. But predators such as cats and snakes destroy nearly a third of unprotected nests, another study showed.

As the mosaic of farm fields and hedgerows gives way to a monoculture of fescue lawns and ornamental shrubs, animals lose places to feed and hide.

Mecklenburg is down to its last known nesting pair of loggerhead shrikes, a grassland bird known for impaling its prey on thorns.

A noose of new homes and the Interstate 485 outerbelt is closing around a 45-acre wetland preserve the Catawba Lands Conservancy owns in southwest Mecklenburg. Spotted salamander numbers there have plummeted over the past decade.

Trends are hard to track because not many people count the creatures that slither and crawl.

"Nobody knows what happens to turtles if the land all around their pond becomes a neighborhood," said Steve Price, Davidson's herpetology research coordinator. "Do they leave? Do they stay? We don't know."

The college, with grants from the National Science Foundation, is studying how development affects salamanders and turtles.

Other human-induced dangers kill untold millions of animals each year.

Migrating birds hit communication towers in the night. Marauding cats kill songbirds and small mammals. Introduced species, such as Norway rats and fire ants, kill natives and compete for food. Toxic mercury shows up in the injured bald eagles treated at the Carolina Raptor Center.

"These things all add up," said Chris Moorman, an urban-wildlife specialist at N.C. State University. "Biologists don't have a good feel for it. You can study how many birds are killed by a tower each year, but how do cats and loss of habitat all add up?"

Barred owls favor old-growth forests. As trees fall across Mecklenburg's suburbs, the stately willow oaks of Myers Park, Dilworth and Eastover have become favored haunts.

The birds are doing well, said ornithologist Rob Bierregaard, who found no difference in the reproduction of city owls compared to their country cousins.

The presence of the inky-eyed raptors, he says, shows that the ecosystem still works. But biologists hedge about the future.

"It's sort of like taking the rivets out of an airplane," Bierregaard said. "We really don't know how many species we can afford to lose before the whole place starts to unravel."

Wildlife Winners ...

-- Coyotes, now scattered from Chicago to Charleston, howl among suburban backyards.-- White-tailed deer so crowd county nature preserves -- about 1.5 per acre at Cowans Ford in northern Mecklenburg -- that annual hunts, an alternative to disease and starvation, are held.

Losers ...

-- Freshwater mussels, bellwethers of polluted water, are the most endangered creatures in North Carolina.

-- Birds that nest in tree cavities (Brown-headed Nuthatches), grasslands (bobwhite quail) and shrubby habitat (prairie warbler) have declined in recent decades.

And survivors ...

-- River otters, not seen for decades, have reappeared in city streams. Improving water quality provides more prey.-- Wild turkeys, an elusive game bird, have soared in numbers as wildlife officials work to boost stocks.

Living With Wildlife

To learn how to coexist with wildlife or create habitat, visit these sites:

N.C. Wildlife Federation: www.ncwf.org look under "Programs" or call (704) 332-5696.

N.C. Wildlife Resources Commission: www.ncwildlife.org/fs_index_06_coexist.htm

National Audubon Society: www.audubon.org/bird/at_home/index.html

Tips:

-- Keep cats indoors. They kill millions of birds and small mammals each year.

-- Don't leave pet food outside or garbage unsecured -- they invite nuisance animals.

-- Install chimney caps to keep birds and other animals from getting trapped.

-- Create wildlife-friendly backyards by planting native trees and shrubs and adding water features.

-- Don't assume baby animals are orphans that need rescue. Mom is probably nearby.

Bruce Henderson: (704) 358-5051.

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Copyright (c) 2006, The Charlotte Observer, N.C.

Distributed by Knight Ridder/Tribune Business News.

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Source: The Charlotte Observer (Charlotte, N.C.)

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