And soon, so was Roisum. One day at work in the late 1990s, Roisum fell ill in a hurry. His temperature leaped to 103.5 degrees Fahrenheit. He tried to drive home, but reached only so far as the emergency room. For the next three days doctors marinated Roisum’s immobile body with antibiotic cocktails. Roisum had been diagnosed with Lyme disease, an incapacitating bacterial infection transmitted by a tick—a tick once referred to as the deer tick.
Since its emergence in 1975, Lyme disease—named for the town hosting one of the first outbreaks—has spread from its Connecticut bull’s-eye across the forested East. It sprang up in the Great Lakes region, in the forests of the West Coast. The U.S. cases have reached fifteen thousand to twenty thousand per year—an underestimate by a factor of ten, according to some. Lyme has vaulted to the rank of fastest-growing infectious disease in the United States.
Traced to an infection by Borrelia burgdorferi, a spirochete bacterium related to the syphilis germ, Lyme, if left untreated sometimes leaves its victims double-visioned and seizing, with their skin burning as if on fire. Doctors mistake Lyme for chronic fatigue syndrome, rheumatoid arthritis, multiple sclerosis. Lyme, the great masquerader, commonly goes misdiagnosed and untreated. In its later stages the disease produces meningitis and facial paralysis, hallucinations and panic attacks. Long-term victims sometimes wind up in wheelchairs, some in the grips of crippling pain, pondering suicide. And it seems that wherever Lyme erupts, deer are there in numbers.
Now thirty years beyond the first outbreak, there comes a new twist to Lyme’s baffling ascent to the ranks of public enemy. A once simplistic equating of too many deer with outbreaks of the disease has since grown complicated. It is indeed true that a single deer may harbor thousands of adult black-legged ticks whose species indeed harbors the Lyme germ. But other accomplices have emerged. For it is not the adult ticks, rather their tinier nymphal offspring that tend to acquire and pass the Borrelia bacterium to the human bloodstream. And those dangerous little nymphs commonly get their doses of Borrelia by sipping blood from chipmunks and white-footed mice, two otherwise handsome and ubiquitous denizens of the forest understory. It now appears that one can better predict a hot zone of Lyme by censusing its mice.
Much of the above has been informed over the last twenty years by the work of Richard Ostfeld and his colleagues at the Institute of Ecosystem Studies in Millbrook, New York. And though convinced of the mouse’s giant role in harboring the epidemic, Ostfeld himself is not ready to acquit the deer. Ostfeld’s hypothesis holds that in precolonial times, both deer and ticks were far fewer than today. Sometime in the mid- to late-twentieth century the rebounding deer herd crossed a population threshold, triggering a historically tiny population of ticks to turn abnormally huge. As much as mice may have harbored Lyme’s bacterial reservoir, it was the defanging of America and the ensuing eruption of deer that sent the legions of transmitting ticks swarming the mice’s way, and on up the pant legs of the American populace.
Head-on
When he recovered, Gary Roisum went back to Huntley Meadows to again face the vandals holding court in his castle. His predicament was nothing if not common. Almost every park manager in Fairfax County was by then reporting to work with a cud-chewing boss in charge. The science of deer management had not yet devised a workable system of chemical contraception. Translocations had turned into costly disasters, with the captured deer dying in droves, never mind the awkward question of where on earth any surplus deer were supposed to go. To the managers’ minds, there was only one practical option left, the mention of which invariably sent the local politicians ducking for cover. “Every time we’d bring it up to the board of supervisors,” said Roisum, “everybody was afraid we were going to be turning a bunch of guys loose with a shotgun and a six-pack to go after deer.”
On an October morning in 1997, Roisum’s lethal rationale gained a horrific measure of leverage. That morning, Sheryl Czepluch, a forty-nine-year-old Fairfax school librarian, was driving to work along a suburban two-lane road when up ahead a deer jumped the guardrail. The deer bounded onto the asphalt and into the path of an oncoming Mercedes-Benz. The Mercedes launched the deer through the windshield of Czepluch’s Volvo. Czepluch’s head and chest bore the impact of a hundred-pound sledgehammer. Her collision was one of a million and a half nationwide, her death by deer added to the conservatively estimated 150 to 200 human casualties every year. Soon thereafter, Fairfax began shooting its deer.
The county hired veteran wildlife biologist Earl Hodnett out of retirement, and he launched one of the country’s most sophisticated guerrilla campaigns against the suburban deer. In the blackness of night, in trucks painted olive drab, Hodnett’s crews of police sharpshooters began rolling into the deer-plagued parks of Fairfax County. Helicopters hovered over-head, searchlights shooing romantic couples and loafing drunks clutching vodka bottles. From the back of the trucks, the sharpshooters stood armed with high-powered rifles fitted with silencers, scanning the woods with infrared night vision scopes, freezing their targets in the beams, and delivering each a single shot to the head.
Since the shooting began, the deer numbers have started to drop, from the obscene to the merely stupendous. Aiming to eventually stabilize the deer population at fifteen to twenty per square mile, the job of Hodnett has become that of the Dutch boy plugging the dike.
Beyond the parks, Hodnett’s jurisdiction covers the backyard battleground, where punch-drunk gardeners have resorted to rigging electric scarecrows, spreading lion dung, peeing in their patches, and ultimately dropping their trowels in defeat. It is Hodnett who hears about it when the king of a gated castle in the posh woods of McLean loses ten thousand dollars in custom landscaping to the local gang of deer. It is Hodnett who fields the complaints about audacious deer climbing three-story decks to reach the flower boxes.
Hodnett has also become Fairfax’s de facto epidemiologist. “People call me complaining one of their kids has Lyme disease. And their dad has it. And the neighbor across the street and another neighbor down the street has it,” said Hodnett. “They’ll rattle off a dozen people on their street that either had it this year or over the last couple years. They complain to me as if I have the ultimate power to take care of the deer problem.”
Hodnett is Fairfax County’s sole wildlife biologist—one man versus fifty thousand deer. “I’d say seventy-five percent of my job is deer,” he said, noting that the deer have lately added reinforcements. “The remaining quarter is Canada geese and beavers and creatures in the attic making noise.”
It is perhaps more than coincidence that this new suite of pests now flooding Hodnett’s to-do list were once—like the white-tailed deer—more commonly considered prey.
SEVEN
Little Monsters’ Ball
IN THE LATE 1970S, ornithologists and amateur bird-watchers of the eastern United States began to grow uneasy about a certain hush sweeping over their favorite woods. It seemed the summer chorus of songbirds was falling fainter by the year.
They could not pass it off as a dip in some recurring cycle, or an inflated memory of the good old days. Shortly after World War II, a volunteer corps of bird-watchers from the Audubon Society started formalizing their weekend outings with an annual census of breeding birds. The society faithfully compiled and published the surveys for the next forty years. What the birders felt in their guts, their census now confirmed as fact. A certain suite of migratory birds was in sustained and serious decline.
One of the longest-running censuses covered Rock Creek Park, a nine-mile corridor of forest snaking through the heart of the District of Columbia. Walled in by the embassies and apartment towers of urban Washington, Rock Creek Park appeared as one of the Mid-Atlantic’s mightiest magnets for avian species funneling through the eastern megalopolis. In its postwar heyday, the park and a few of its urban green outliers had become the birding grounds for legends of the genre, Roger Tory Peterson and Rachel Carson among them. It was granted as fact among the binocular-clad
cult that the highlight of springtime in Washington was not the blossoming of the cherry trees but the return of the warblers.
Now the return of the warblers could no longer be assumed. By the 1970s, the Kentucky warbler, northern parula warbler, black-and-white warbler, and hooded warbler were dropping off the charts. Fellow migrants such as the Eastern wood-pewee, Acadian flycatcher, scarlet tanager, ovenbird, red-eyed vireo, and wood thrush were down by half. By 1986, the sum of all breeding pairs in Rock Creek had plummeted by two thirds.
Scientists weighed in with their best guesses. There was always that widening black hole of tropical deforestation. With every autumn, the bulk of the migrants would funnel south into Central America, to an area of land far smaller, into forests felled more rapidly, than the breeding grounds to which the birds returned every spring. Yet the troubles in the tropics could not explain the birds disappearing from certain northern forests and not others. In the giant unbroken tracts of the West, there seemed to be no problem. It was mainly east of the Mississippi, where the forests were being chopped and diced, that the birds were most rapidly disappearing. As much as tropical deforestation loomed as an undying threat, something equally worrisome and far murkier was descending on the northern breeding grounds.
The North American concerns came to focus on fragmentation, the process and end-product by which vast swaths of forest were being cut into smaller isolated woodlots. The forests had become habitat islands. And for a budding generation of conservation biologists, islands had become the top-most topic of fascination and fear.
Their fixation was fueled in large part by Robert H. MacArthur and Edward O. Wilson’s pioneering theory of island biogeography, offering an explanation for the life and death of species, as exemplified through the faunas and floras of oceanic islands. The theory states, here in extreme shorthand, the deceptively simple observation that the smaller and more isolated the island, the fewer the number of species it is ultimately apt to harbor. The diversity harbored by the island eventually arrives at a balance point between colliding forces. Those main forces are extinction and immigration—the chance of extinction growing greater, the chance of immigration growing smaller, as the islands shrink, and the mainland disappears over the far horizon.
That, for the biologist, was the fascinating part. The fear, for the conservationist, came from speculating how well the theory might hold for the mainland, how well it might predict the demise of many species living on what, in essence, were mainland islands. The evaporating forests of the eastern United States were one in a list of ecosystems that had been set adrift between widening gulfs of asphalt, concrete, brick, and steel. It seemed reasonable to expect similar problems facing inhabitants of such lonely little woodlots as with those on specks of land far upon the sea. As living space decreased, the islanders’ numbers would ratchet down in step. At some point the little group’s survival would become an issue. All other things being equal, smaller populations would ultimately be less resilient to the various bumps and potholes of life. Drought and plague, fire and flood—jolts enough to merely wobble a robust population—could topple those of tinier numbers. And such a little clan of castaways, so far removed from the motherland, was less likely to be rescued by replacements happening across the formidable gulf.
It was such analogous speculation that had the science-minded bird-watchers of places like Rock Creek wondering where the bottom might lie for their embattled island of birds. If there was nothing to be done about it—given the prospects of reverting the nation’s capital to temperate deciduous forest—there was at least the duty to determine the causes of death. The interrogations turned back again to fragmentation, and the ecology of life on the ever ubiquitous edge. Tests would confirm that it wasn’t the physical edge per se that was draining the little migrants. The birds had no measurable hesitance to nesting right up to the forest’s brink. The edge itself was innocent enough. But the same could not be assumed of that suspicious cast of predatory characters that had lately come to lurk there.
Empty Nests
In the early 1980s, finding his songbirds in free fall, a Princeton student under the tutelage of John Terborgh took a stab at fingering the cause. From the beginning, David Wilcove’s leading suspect was predation.
Wilcove had recently become aware of the experiment on Panama’s Barro Colorado Island, where the bird species had been blinking out since the island’s formation sixty years before. On the island, Bette Loiselle and William Hoppes, two graduate students from the University of Illinois, had set out lines of wicker nests filled with commercial quail eggs, and returned to find most of them raided. It struck Wilcove—as it had his adviser, Terborgh—that the dropping bird counts of Barro Colorado uncannily reflected those from his homeland forests in the eastern United States. There was an added hint of coincidence in that the chief suspect for the egg burglaries on Barro Colorado was the coati, whose North American cousin, the raccoon, was at that time multiplying to unheard of numbers.
And the raccoons weren’t alone. The backyard menagerie of modern America had come to include a glut of blue jays, crows, squirrels, and opossums, scuttling among pet dogs and house cats by the hundreds of millions. With wolves and cougars and eagles no longer patrolling what was left of the great American forest, the lower-ranking predators had been granted free reign. And all came well fed by an endless gravy train of pet food and bird seed, cornfields and garbage cans. (The raccoons lording over Long Island were reported to have doubled in body size.) To Wilcove, the subsidized, fearless fauna of suburbia appeared as something more than a motley bunch of beggars. Wilcove saw in each a potential predator of the missing songbirds.
For his test sites, Wilcove sought out extremes on the ecological spectrum. A half hour’s drive north of Washington, D.C., he singled out a set of isolated forests from the suburbs and farmland of Maryland, some as small as ten acres. These were his island analogues. For his mainland counterpart, Wilcove ventured four hundred miles south, to the half-million-acre Great Smoky Mountains National Park, refuge of the biggest tract of virgin forest in the East.
In the fashion of Loiselle and Hoppes, Wilcove laid out lines of wicker nests through his woods, from edge to forest interior. He placed some at the base of trees and shrubs, affixed others on the lower branches, simulating the nesting habits of his species of concern. And like Loiselle and Hoppes, he returned to find scenes of carnage.
Within a week, in the patchwork forests of Maryland, something had plundered most of Wilcove’s makeshift nests. And the closer to the civilization, and the nearer to the ground, the more complete the plunder. Seventy percent of Wilcove’s suburban nests lost eggs. In the dirt around those nests he read the tracks of dogs, cats, raccoons, opossums, skunks, and blue jays. Just to make sure, Wilcove sat and waited in a blind. Within half an hour, a blue jay flew in and speared an unguarded egg.
Meanwhile, down deep in the spooky wilds of the Smokies, where the bears and the bobcats still ruled the woods, Wilcove’s nests rested safely. All but two in a hundred remained unscathed at week’s end.
Damning as they might have seemed, such numbers could only be trusted so far. Wilcove admittedly wasn’t as crafty at hiding nests as his subjects were. One could imagine a particularly industrious Maryland raccoon clueing in and following his lines like stashes of Easter eggs painted in neon. Still, there was no waving away the acute contrasts between the sheltered wilds of the Smokies and the tamed and treacherous outskirts of Maryland. Life in the little woods, for certain little birds with low-lying nests, had become ten to fifty times more dangerous. That, concluded Wilcove, was a big reason why such pristine façades as Rock Creek Park had become so frighteningly quiet.
Another factor was a fellow songbird called the brown-headed cowbird. Once primarily a grassland bird, the cowbird had in earlier times practiced a living snagging insects flushed by the hooves of the bison herds. To procreate while otherwise keeping up with the moving feast, the cowbird had taken to laying its eggs in the
nests of other birds, enough of which never caught on to the ruse, thereby raising cowbirds at the expense of their own nestlings. As the bison were replaced by cows, and the grasslands migrated eastward in the form of grain fields and pastures, the cowbirds followed along. They advanced on the front of the retreating forests, into the territories of songbirds unschooled in the parasitic ways of cowbirds. Woodland warblers rather suddenly found themselves scrambling to feed the begging maws of cowbird nestlings twice their own size.
And then there were the tropics at the other end of the line. The forests of Latin America, to which many of the migrants returned every fall and winter, were falling at spectacular rates. Guatemala, by way of example, was on pace to be all but denuded by the year 2025. Radar images tracking the clouds of migrants as they made their way north from the Yucatán Peninsula to the Gulf shores of the United States showed their numbers shrinking by half in one twenty-year period.
Wilcove’s predators were the final straw. Given the squeeze of shrinking forests and the infestations of cowbirds on populations already hovering so dangerously close to the ground, the unprecedented swarming of the bottom-rung predators had become the unbearable weight. “We have rather profoundly changed the nature of predation as a natural phenomenon over much of this country,” said Wilcove. “We have greatly increased the number of mid-sized predators, greatly decreased the number of large predators, and there’s a host of ramifications that stem from those changes.”
Keystone Coyote
Where the Wild Things Were Page 14