The Coming Climate Exodus: What We’re Doing to Help Wildlife’s New Migration
For black bears, Florida’s State Road 46 is one of the deadliest motorways in the United States. It winds east-west for some 50 miles, skirting Seminole State Forest, one of the state's key bear habitats. Since the year 2000, more than 100 bears have been killed each year in collisions on Florida roads like this one, and for the last two decades around 80 percent of total bear deaths in the state came as a result of such accidents.
These deaths are a tragic outcome of what conservation biologists call “fragmentation,” which occurs when a species’ habitat is cut into small pieces by human infrastructure like roads and developments. Fragmented populations are vulnerable to threats including starvation, genetic isolation, and local extinction. If a fragmented population of bears can’t follow seasonally available food, and can’t deepen their gene pool with new mates, their chances of long-term survival are slim.
Conservationists now have an unexpected set of collaborators: the employees of state and federal transportation agencies.
Luckily, bears that want to cross State Road 46 are better off today, because it now features an underpass designed specifically with their needs in mind. Passageways like this one are elements of wildlife corridors, interlinked parcels of protected land that connect fragmented habitats. They helped to hasten the removal of the black bear from Florida’s endangered species list in 2012.
For more than 20 years, wildlife corridors have been among the strategies conservationists used to make sure all sorts of animals were able to move around in search of food, mates, and territory. But today, climate change is forcing these specialists to change the way wildlife corridors are designed. As warming accelerates, animals and plants are starting to change the way they travel, generally moving north or to higher elevations in search of the cooler temperatures they’re used to.
Will our roads and buildings stand in the way of this exodus? New partnerships and tools suggest that we’re at least doing our best to make sure they don’t.
New policies make an old enemy into a friend
The first piece of good news is that conservationists are no longer working alone. Legislation has given them a new and unexpected set of collaborators: the employees of state and federal transportation agencies. These are the same people who, as designers of roads and bridges, used to be the chief agents of fragmentation. But a few key pieces of law seem to have suddenly changed that.
In 2001, federal legislation created a State Wildlife Grant, which set aside money to help protect animal species that were rare, endangered, or whose numbers were simply unknown. Four years later, the passage of the 2005 Transportation Bill required planners seeking federal funding for roads and public transportation to consult with their local wildlife agencies early in the planning process. The bill put wildlife managers in partnership with transportation workers for the first time.
Different species have different requirements, so the goal is to find the habitat where the different species’ preferences overlap.
A third piece of legislation came in 2008, with the founding of the Western Governors’ Wildlife Council. Created to coordinate conservation efforts across 19 states as well as three U.S.-administered Pacific islands, the council works to identify crucial habitats and to insure that conservation is incorporated into every type of development. The council features a special initiative on wildlife corridors that makes sure that the designs make sense across state lines.
These three projects put biologists and planners on the same team in a way that made conservation a lot easier to do.
“It's amazing that this one sentence in a thousand-page document [the Transportation Bill of 2005] changed the way [transportation planners] did business,” said Dr. Paul Beier of Northern Arizona University, one of the leading experts on wildlife corridors.
But finding accord between conservation and urban planning can be a tricky business, said Kelly McAllister, wildlife biologist at the Washington State Department of Transportation. “In Washington, finding a species with a fixed migration route is almost unheard of,” he said. “You start mapping out areas of suitable habitat across a broad landscape, looking for connectivity between heavily developed areas and agricultural areas. Before you know it, the entire state becomes suitable habitat.”
“The metaphor we like to use is ‘conserve the stage, instead of the actors.’”
The challenge, said McAllister, is giving wildlife managers sufficiently protected, well-defined tracts of land to work with. Different species have different requirements, so the goal is to find the habitat where the different species’ preferences overlap.
It’s often difficult, McAllister said, for scientists to come to an agreement with the Department of Transportation, which is the largest land developer in the state. “But we’re definitely working together on this,” he says.
Beier calls it nothing less than a transformation of the role of transportation agencies, “which until then had been the biggest agents of fragmentation.” After the 2005 Transportation Bill, “suddenly they became part of the solution.”
New tools, new challenges
Another way that conservationists have responded to the new complexity brought on by climate change is by developing and using new tools, including GIS (global information system) mapping software. With GIS-based programs, specialists can zero in on specific aspects of a topographical map by identifying desired features—such as elevation, light, and soil type—and tuning out the rest.
Out of this way of seeing comes the idea of “land facets,” which are discrete parcels of land that offer specific and relatively permanent types of habitat to wildlife. For instance, “high-elevation north-facing slopes with rocky soils” is a land facet, one favored by bighorn sheep. “Low-elevation flats with thick soils” is another, which pronghorn antelope prefer. The aim is to define wildlife corridors based on long-lasting geographical features, aspects of the landscape that aren’t liable to change with rising temperatures.
As warming accelerates, animals and plants are starting to change the way they travel. Will our roads and buildings stand in the way of this exodus?
“A hundred years from now, a stand of ponderosa pine might become a stand of juniper as things heat up,” said Jeff Jenness, a developer of the GIS-based software that conservationists and planners use to identify land facets. “But the hill under those trees will largely remain the same. By identifying land facets, we can sort of predict this change and maintain an environment that supports a number of species.”
Land facets tend to harbor predictable assemblages of species, so creating a corridor that includes different kinds of facets should provide animals with the geographic diversity they need to survive, Jenness said.
“The metaphor we like to use is ‘conserve the stage, instead of the actors,’” adds Beier. “Or, if you like sports, ‘conserve the field, instead of the players.’”
While older methods concentrated on the specific needs of so-called “focal species”—threatened or endangered species singled out for conservation—approaches based on land facets seek to support a broad swath of organisms by focusing first on the land.
As climate change raises sea levels, changes temperatures, and increases the likelihood of catastrophes like droughts and storms, some species will almost inevitably be lost. At the same time, conservation biologists are doing their best to make sure that plants and animals can find safe passage to cooler climates. With any luck, these living things will be around to join us as we adapt to a changing climate.
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