Wildlife in the Fast Lane
by Howard Youth
High in the Cascade Range, beyond the reach of sport utility vehicles, lies snowy, roadless wilderness that is one of the lynxs last strongholds south of Canada. Vulnerable to habitat disturbance and trapping, the reclusive, tuft-eared lynx has vanished from much of its range. These stresses aside, lynx are vulnerable to predators such as pumas and coyotes, and cannot compete with bobcats, their more adaptable cousins, which flourish in less snowy environs.
"The research isnt entirely clear, but we know that the only places where lynx persist in the Lower 48 are roadless," says Mitch Friedman, executive director of the Northwest Ecosystem Alliance, a group that battles to save wilderness areas. "The most likely reason for that is that roads give access to trappers, competitors, and predators. Also, if roads are being used by anything that eliminates snowthat melts it, plows it, or compacts itthey are a way coyotes, cougar, and bobcat can have greater access to the high country."
Cars themselves can become de facto predators. In the late 1980s, an effort to re-introduce lynx into New Yorks Adirondacks failed after cars traversing the road-riddled area killed many of the released animals. "A closed road is certainly better than an open road," says Friedman. "But the absence of a road is better than a closed road."
The
shotgun marriage between roads and adjacent wildlife habitats
is often a complex, vexing relationship, especially when it
comes to wide-ranging creatures such as lynx, bears, and wolves.
As cities large and small grow, roads inevitably spill across
the land, cutting through wildlife habitat along the way.
It is hard to imagine life without roads. Arteries of human life, they move our commercial and personal goods, get us to work, return us home, and get us away from it all. Ever since Native Americans followed bison and deer trails across prairies and through woods, followed by the European settlers and their horses and wagons, North Americans have favored taking the road more-often traveled.
As we trundle over roads, we often overlook their great ecological impact. A quick peek at some road statistics hints at their heavy footprints on the land. For instance, road corridorsthe area including roads and their maintained marginscover about one percent of the United States, or an area about the size of South Carolina, according to a 1998 study published in the Annual Review of Ecology and Systematics by Richard T. T. Forman and Lauren E. Alexander. However, the authors stress that roads ecological impacts extend further, affecting 15 to 20 percent of the United States. All together, the countrys public roads span 3.87 million miles. About ten percent of these crisscross national forests for a total of 380,000 milesenough to circle the earth 15 times.
Sudden Impact
As any driver who looks beyond the steering wheel knows, roads arent bad for all wildlife. Keep your eyes open along the margins of Interstate 95 in Maryland and Virginia and you will see red-tailed hawks, groundhogs, and bluebird boxes that shelter their namesake birds and other cavity-nesting species. In California and Texas, a raptor called the white-tailed kite has greatly increased its range thanks in part to highway median strips, where it finds a variety of small rodents. Coyotes, notorious rodent catchers, are also common along western roadsides, while un-mowed highway margins, and those seeded with native wildflowers, attract an array of butterflies. Around the world, from Australias busy urban highways to dusty roads cut through the Amazon, a cadre of animals adapted to disturbed habitats flourishes. In remote areas, large cats such as tigers and pumas often use roads for easy travel and to track prey along the forest edge. That is, until a truck or car rolls near.
Roads lead to most of the worlds most important wildlife sanctuaries, the wild playgrounds where we commune with nature. Most of the millions of Americans fueling the $60-billion-a-year wildlife-watching industry view bears, elk, butterflies, flowers, or birds from their cars or from roadside overlooks or trails leading from park roads. Many wildlife biologists do their census work from roads, and the U.S. Geological Surveys nationwide Breeding Bird Survey is conducted by thousands of volunteers who listen and watch birds along set roadside routes.
While roads open the door for naturalists to study nature, smooth pavement and hurtling vehicles often bring drivers and wildlife too close for comfort. In the United States, an estimated one million vertebratesamphibians, reptiles, birds, and mammalsare run over each day. Many animals are drawn to roads by carrion (usually previous roadkills), road salt, or insects. Others are just trying to cross the road. "Sometime during the last three decades, roads with vehicles probably overtook hunting as the leading direct human cause of vertebrate mortality on land," wrote Forman and Alexander. Roads and their attendant vehicles have harmed populations of rare species such as South Texas ocelots, Florida panthers, Florida black bears, and also those of slow-growing animals such as box turtles. Amphibians, many of which cross roads to reach breeding sites such as vernal pools, often decline where cars prevail.
However, road mortality does not seem to dramatically affect populations of adaptable, fast-breeding animals such as opossums, raccoons, gray squirrels, and white-tailed deer. For example, thousands of deer are hit on eastern U. S. highways each year, threatening both deer and drivers. But deer populations still flourish along grassy roadsides. This is true even in heavily developed areas like Montgomery County, Maryland, where Maryland Department of Natural Resources statistics reveal that hunters shot 2,624 deer in 1997, while cars and trucks took 1,902.
Build It and They Might Go
Roadkills aside, biologists find that roads affect some animalsand their habitatsin more serious ways. For one thing, while some animals flourish along the edge habitat created at roadsides, many do not. Also, many animals, both large and small, simply will not cross roads. The treeless earth, which is warmer and drier than surrounding woods or brush, the noise, and the confusion of busy roadways create formidable barriers that often cleave wildlife populations, potentially affecting their genetic variability by limiting breeding possibilities. Studies show that small mammals, turtles, and amphibians often go out of their way to avoid crossing roads, as do a variety of large mammals including grizzly bears and wolves. One study in Germany showed reduced genetic variability in common frog populations following isolation by roads. Roads as narrow as seven-and-a-half feet wide prohibited carabid beetles and wolf spiders from crossing. Another study, which appeared in the Journal of Mammalogy in 1984, found that "movements of prairie voles and, to a lesser degree, cotton rats were restricted by something as seemingly innocuous as a narrow, seldomly used vehicle path" that was less than nine feet wide.
Roads can, and often do, change adjacent wetlands hydrology by blocking groundwater flow and carrying chemicals and sediment to the water. In addition, car tires often transfer weed seeds, many of them exotic species, from one place to another. In these ways, roads can spur changes in plant composition, water level, or water clarity, which in turn can affect declining animal populations.
Just the sound of traffic is enough to affect birds. A Netherlands study revealed that 60 percent of bird species occurred in lower densities in grasslands and woods near highways than away from them. While pinpointing the reasons requires further study, possible causes of the decreased abundance include birds sensitivity to noise and hampered communication due to road noise blotting out the birds calls and songs.
Roadside lighting also confuses wildlife. For instance, young sea turtles emerging from beach nests at night may head for street lamps instead of moonlight and never find their way to the ocean. Street lights also disrupt amphibian breeding around wetlands, while light reflected off road surfaces tricks mayflies, important insect prey for fish and other aquatic predators, into laying their eggs on roads instead of in streams.
However, one of the most dangerous aspects of roads is that they carry people into wilderness.
Road Meat
One of Africas most serious wildlife crises involves logging roads carved into Central Africas moist tropical forests. As wood supplies in Southeast Asia and West African forests have diminished, large logging companies now set their sights on Central Africas more remote and less disturbed tropical rainforests. In areas where logging begins, biologists are finding that large animals often vanish. While primates and other wildlife can sustain limited logging in their habitat, they are disappearing from these areas for another reason: heavy hunting. In countries such as the Republic of the Congo, timber companies bring in loggers who sustain themselves and their families on wild meat and moonlight as market hunters, selling "bush meat"meat from elephants, gorillas, chimpanzees, duikers, and other forest animalsin city markets. The expanding logging-road network fuels a growing wild meat industry and conservationists, noting widespread declines in large animals, are demanding that timber companies and governments help halt the rampant hunting before it decimates populations of such well-known animals as western lowland gorillas, forest elephants, and chimpanzees.
"In general, people in Africa have always harvested wildlife, mostly for their own subsistence," says John Robinson, the vice president for international programs at the New York-based Wildlife Conservation Society. "The big issue from a conservation standpoint is the commercialization of that trade. As people moved into cities and retained a preference for wild meat, they have developed a broad market."
"The logging roads are dirt roads carved out so they can move big trucks with logs," says Robinson. "Theyre great roads. Theyre straight, flat, well-graded, and allow very rapid access back into the forestand easy transportation for getting stuff out, be it wood or wildlife."
The dangerous combination of road-building and commercial wild meat hunting is not unique to Africa. "Were keying on Africa primarily because its happening right now. It already happened in Asia, and it may happen in Latin America," says Robinson. While the African bush meat crisis has yet to be tackled by governments and logging companies, some lending institutions including the World Bank now define their ending policies to limit the exploitation of forest wildlife around forestry operations.
Of Wilderness and Wanderlust
Meanwhile, back in North America, conservationists and loggers are battling over the future of areas untouched by gravel, dirt, or asphalt. "Wilderness areas are by definition roadless, with roads built only to their edges. They are thus advertised as unique, as indeed they are," wrote essayist, conservationist, forester, and Wilderness Society co-founder Aldo Leopold in Round River, published in 1953. Leopolds writings and conservation work helped inspire the 1964 Wilderness Act, which now permanently protects about 104 million acres from road-building and other disturbances.
Conservationists estimate that about half of the United States remaining roadless wilderness is currently protected under the Wilderness Act. The Wilderness Society and dozens of other environmental groups are urging the federal government to protect more acreage in the largest remaining undesignated roadless areas in national forests and on Bureau of Land Management lands. "Our hope is that the administration will permanently protect roadless areas because logging, road-building, and mineral developments unduly fragment critical wildlife habitat in the few remaining refuges there are in our national forest system," says Ken Rait, the director of the Heritage Forests Campaign, which represents 200 scientists, 460 conservation-related organizations, and more than 300 religious leaders. Rait and others believe that protecting roadless areas in national forests provides the best hope for saving lynx, grizzly bears, wolverines, and other large carnivores, as well as sensitive aquatic creatures like salmon, which decline when logging-road erosion sullies their spawning streams.
Research bears this out. For example, a University of Montana study found that more than 70 percent of western Montanas healthiest watersheds occur in wilderness areas. Studies of Minnesota and Wisconsin wolves, many of which live on national forest land, revealed that wolf breeding success depends upon low road densities (not exceeding 0.93 mile per square mile), not only because high road densities directly threaten wildlife, but also because they facilitate another menace poaching.
For sheer wanderlust and vulnerability, the grizzly bear has conservationists most worried. Biologists and conservationists now believe grizzlies and other large carnivores cannot survive just in existing national parks. For example, in the Northern Rockies, where fewer than 1,000 grizzlies remain, the bears have home ranges up to 480 square milesan area about one-third the size of Rhode Islandand their wanderings take them from national parks into surrounding national forests and private land. Many conservationists believe road-building and use should be restricted in grizzly country, and that larger reserves, including buffer zones around core areas like Yellowstone, Glacier, and Banff national parks, will be needed. The trouble is that roads, in addition to fragmenting bear habitats, inevitably bring people and the normally shy bears together. "The bears typically avoid traffic and roads," says Alliance for the Wild Rockies Executive Director Mike Bader, who recently published a study on bears and wilderness. "Very few bear deaths are collisions with automobiles. Most of them are management removals of habituated animals [that now eat human foods] and a lot of them are illegal killings or surprise encounters."
An 18-month moratorium on road building in many national forests (covering a total of 33 million acres) will expire late in 2000, when the U. S. Forest Service, which builds many miles of roads per year, will unveil a new policy regarding roadless-area protection. In the meantime, while some national forests are closing roads to protect water quality and wildlife, others plan to open new roads into sensitive areas, including some used by grizzly bears.
Even national parks have road headaches. Plagued by traffic jams that pollute park air and water and disturb wildlife, many parks are seeking ways to stem the flow of cars and RVs, while demands on the parks grow. In Alaskas Denali National Park, where visitors must park and take a bus into the park to minimize disturbance to wildlife, there are moves to build a new access road into the heart of the park. Other planned roads threaten parks in the U. S. West, while existing highways and paved park roads from the Everglades to Yellowstone to Albertas Banff National Park create dangerous obstacles for protected wildlife.
A Rough Road Ahead
Road ecology is coming of age, and not a moment too soon. More than ever before, the complex issues involving wildlife and roads are beginning to draw conservationists and road planners together to find a middle ground that allows the best coexistence between animals and motorists. Roads will remain a very important part of our lives. But how, where, and whether to build new roads through wildlife habitat, and how to retrofit current roads to minimize ecological damage, have become important environmental concerns in many areas. Not long ago, road-builders and planners rarely considered local ecology or asking biologists for guidance. Today, thanks to more stringent environmental laws and greater public concern over wildlife issues, planners in North America, Europe, and other areas are more likely to consider the natural contours of the land and avoid areas, such as wetlands and valley bottoms, frequented by wildlife. Wildlife managers and planners are beginning to work more closely to set speed limits, road densities, and road sizes through wildlife-rich areas, and to plan bridges that cause minimal disturbance to wetlands and water quality.
Permeability a roads ability to accommodate wildlife movement with minimal fatality is one of the greatest challenges when roads run through wild areas. Perhaps no other state has worked as hard to get a handle on this problem as Florida, the countrys fourth most populous state and one of its most biologically diverse. Increased traffic and road-building threaten many of the states animals, including the Florida black bear. Like the endangered Florida panther, this wide-ranging omnivore, which the state lists as threatened, has suffered from habitat loss and fragmentation and from roadkills.
Last year, a record 88 black bears died on Florida roads, and the population now may be as low as 1,500 animals. (The state once hosted an estimated 12,000.) "While habitat loss is the bears number-one threat to survival, roadkills are the single most direct cause of mortality," says Tom Uniack, a Defenders of Wildlife program associate. Uniack works on the Habitat for Bears Campaign, a joint effort by Defenders and the Florida chapter of the Sierra Club to protect habitat and prevent habitat fragmentation and roadkills in Floridas bear country.
This group works closely with the Florida Fish and Wildlife Conservation Commission (FWC) and Florida Department of Transportation (FDOT), two state agencies that work together to save the states bears using a blend of modern technology and proactive planning. A few years ago, the FWC finished a study that pinpoints wildlife habitats vulnerable to fragmentation, and produced maps marking bear kill locations. It has also begun to study bear movements in Ocala National Forest, where two state roads cross bear habitat. The FDOT uses these resources and the FWCs counsel when deciding where to site bridges, road expansions, or re-alignments that might affect bears or other wildlife. These agencies pooled their resources to install about 30 underpass structures in central and southwest Florida. Some of these underpasses, which usher animals beneath the roadway, are designed to keep Florida black bears out of harms way, while many others are meant to keep Florida panthers from stepping in front of cars. A variety of other animals also use the underpasses. Planners placed most underpasses where regular animal movement occurs or in problem areas where roadkills were reported. Fences are often an important part of the underpass strategy: They bar animals from crossing the road while funneling them toward the underpasses. For panthers, of which only 30 to 50 remain, such mitigation efforts have reduced roadkill loss from ten percent annually to two percent.
These days, imagining a future without roads is as difficult as picturing a world without wildlife. From reining in Africas bush meat markets to protecting lynx and bears, conservationists, loggers, and road-planners will have much to discuss for years to come. And although the road may prove rocky, its one we all must travel down together.
ZooGoer 28(5) 1999. Copyright 1999 Friends of the National Zoo. All rights reserved.
