Bambi Must Die
A little over five years ago, I was driving back to Minneapolis with my friend Dick after a May fishing trip in north central Minnesota. As we headed south on Highway 64 through a pleasing mix of swamp, forest, and farmland, a white-tailed deer appeared in the middle of the highway. It just stood there, motionless in the dusky fog. With no chance to swerve or brake, we plowed squarely into the animal.
Neither Dick nor I was injured. The car--my grandmother's wheezy old Plymouth Horizon--was less fortunate. After climbing out to survey the damage, the first thing I noticed was the crumpled front end. The right headlight dangled from a single wire. Antifreeze gushed from the radiator, pooling in the road.
Of course, the deer was dead, sprawled out with long skinny legs akimbo and guts everywhere. It looked like someone had spilled a cafeteria tray full of sloppy joe. I could tell the deer was a doe; there were no antlers or antler buds that would indicate a buck. I took a closer look and there, in the fading light, I noticed the outline of a nearly full-term fawn, dislodged from its mother's womb by the violent collision.
There was yet another horror. Dick spotted it first: something small, making a flopping motion on the center line about 30 feet away. At first, I thought it was a severed limb, perhaps in some final, nervous spasm. I walked over to investigate, whereupon I found a spectacle as pathetic and macabre as anything I'd ever laid eyes on. The doe, it turned out, had been pregnant with twins. I had just located the other sibling.
Aside from its most gruesome aspects, there was really nothing unusual about my experience. In 2001--when the state's whitetail population was smaller than it is today--the Madison-based Deer-Vehicle Crash Information Clearinghouse estimated that there were approximately 19,000 such collisions in Minnesota. According to statistics from the Minnesota Department of Public Safety, that is roughly the same number of accidents drunk drivers caused in Minnesota over the five-year period from 1998 to 2002.
And yet the majority of Minnesotans--hunters and nonhunters alike--still love the whitetail. After all, for most of us, they are the largest animals we have an opportunity to see in the wild. Accordingly, they are a staple of our calendar art, the subject of the nature paintings that hang on the walls of cafés up north and in our dens and garages back home. A few years ago, when the Department of Natural Resources decided to issue special license plates as a fundraiser, it selected the iconic image of a buck with a big rack for the inaugural plate. Below the buck were the words, "Protect Critical Habitat."
The implications of this credo were clear: Deer are a vital natural resource in Minnesota and they require active protection.
For a long time, even after I'd totaled two vehicles in collisions with deer, I continued to hold a similar view. I was impressed by the whitetail's grace and good looks. I loved to watch deer in the woods, to marvel at how they could be there one moment and, in a blink, disappear. More important, I considered deer a symbol of the wild. When I spotted a deer on a hike, I took it as a sort of assurance that not everything has been despoiled and that the natural order remains at least somewhat intact.
As it turns out, I was full of it. Fact is, the white-tailed deer is about as apt a symbol of wilderness as a rat or a pigeon--or if you're feeling more charitable, a grackle or a raccoon. Contrary to what most of us might think, whitetails don't thrive because we have been good stewards of the land; they thrive because we have been brutal to it. As is the case with rats and pigeons, whitetails prefer a landscape degraded by man, not untouched wilderness. They love the clear-cuts in the forests, the land subdivided by suburban developers, the crop fields farmers cultivate.
The deer love all these places. And in whatever way an animal with such a small, smooth-surfaced brain is capable, they probably love us. Or at least they should--especially the folks over at the Department of Natural Resources and the United States Forest Service. Along with countless private property owners, these wildlife managers have made collective decisions about hunting policies and land stewardship that have ensured that the herd continues to swell.
As a result of all this, and of several unusually warm winters, Minnesota's whitetail population now stands at a record 1.2 million head. That fact is all the more astounding when you consider that hunters killed 290,000 deer in Minnesota last fall, which was, it so happens, also a record.
When people complain about deer, they are likely to cite damage to their cars, gardens, or crops. So when game managers try to figure out the appropriate deer population for a specific area, they refer to the "social carrying capacity"--in other words, the amount of deer-related damage that the local citizenry will tolerate before they start demanding sharpshooters or expanded hunting seasons.
But the truth is, even where they are below the social carrying capacity--there are still a few corners of the state where this is true--deer do plenty of damage. It is damage that is much harder to see than a ruined vehicle or wrecked suburban garden but also far more invidious. In fact, a growing body of evidence suggests that our overabundance of hungry whitetails is causing significant, potentially irreversible harm to forest ecosystems. The case against the whitetail doesn't end there. The rising number of deer is also implicated in the spread of Lyme disease, now the most common insect-borne disease in North America.
There is a nasty list of indictments to be brought against our gentle friends of the forest and it leads to an avoidable verdict: Friends, Bambi must die.
In the mid-1980s, Don Waller first began thinking about the harm deer might be doing to the plant communities in hardwood forests. A professor of botany and environmental studies at the University of Wisconsin at Madison, Waller had spent most of his career studying what he refers to as "noncontroversial things, like how plants have sex." But increasingly, his students were urging him to investigate the management--or as he puts it the "mismanagement"--of the national forests. In particular, Waller says, they pressed for more study of the ecological effects of wide-scale logging in the forests of Wisconsin and the Upper Peninsula of Michigan.
Going in, Waller understood what deer hunters and loggers have long known: Logging, especially as it has been practiced in the upper Midwest, creates ideal deer habitat. Whitetails, which wandered across the Aleutian land bridge to the New World 15 million years ago, are today an "edge species." In other words, it's a type of animal that prefers a forest with clearings (whether created by fire, blowdowns, or logging) to larger, unbroken tracts of old growth. As a result of land-management practices, whitetail densities have been increasing at alarming rates. A natural population for a hardwood forest might be between five and ten deer per square mile. But in some areas, Waller notes, Wisconsin has recorded as many as 58 deer per square mile.
When Waller started examining the plant communities of the national forests, he began rooting around the research literature for studies that addressed the effect all these deer might be having.
Despite a surprising dearth of information, it didn't take long for Waller to begin building a case against the whitetail. It just took a botanist's eye. In their surveys, Waller and his colleagues would identify the full-grown trees on a particular forest plot and then look for evidence of natural regeneration--in other words, seedlings. In areas with high deer populations, they discovered, the seedlings of tree species that deer like to eat (white pine, hemlock, sugar maple) seemed to be few and far between. In the areas with lower deer populations, the natural regeneration was more robust.
In Waller's view, the implications were obvious: The forest composition, at least as far as trees were concerned, seemed to be undergoing a significant transformation because of overforaging by deer.
Another important question remained. What was the expanding deer population doing to the most varied part of the forest, the understory plants? To get an answer, Waller referred to the work of John Curtis, a well-known figure in botanical circles for his comprehensive study of Wisconsin plants. During the 1940s and '50s, Curtis performed extensive plant censuses throughout the state, painstakingly recording the species and populations at various plots. Armed with Curtis's data, Waller and his fellow researchers returned to 62 of those sites, where they got on their hands and knees and recorded the exact numbers and types of understory plants they found.
"I expected there would be some changes, but I was surprised by the amount we saw," Waller recalls. Plants that were once common--mainly, grasses and sedges--had become even more common. But plants that used to be relatively rare--wildflowers, lilies, and orchids---had gone into marked decline.
The effects were most pronounced in places where deer hunting had been prohibited and populations had swelled. At Lake Gogebic State Park in the Upper Peninsula and Brunet Island State Park in Wisconsin, for instance, approximately 50 percent of the understory plant species that Curtis had recorded half a century earlier had entirely vanished. By contrast, in the few parts of Wisconsin where the deer populations had been kept low by acute hunting pressure, such as the Menominee Indian reservation, there was still plenty of plant diversity.
Waller looked for alternative explanations. Perhaps, he speculated, the differences were the product of natural growth cycles and varying levels of sunlight. In the end, no other hypothesis stuck. The forest understory was changing, Waller concluded, and whitetails were the main cause.
About five years ago, researchers from the University of Minnesota struck out for the western suburbs and began setting up deer "exclosures"--acre-sized plots of forest with 10-foot high fences to keep the deer out. After erecting the fences, the researchers let nature take its course.
Today, outside the exclosures, where the deer can get at the understory, the ground is still essentially bare--in effect, a biologically impoverished moonscape. Inside the exclosures, however, undergrowth has begun to come back. So far, nine plant species that had entirely vanished from the immediate vicinity have reestablished themselves in the deer-free area--evidence that recovery from the depredations of the whitetail is possible but slow.
"We're finding essentially the same things that they found in Wisconsin," notes Lee Frelich, one of Minnesota's leading ecologists and director of the Center for Hardwoods Ecology at the University of Minnesota. "Deer are one of the major threats to biodiversity in Minnesota."
As the deer population swells, Frelich says, it accelerates what he has dubbed "forest decline syndrome"--a phenomenon characterized by the erosion of soils, the failure of certain keystone tree species to successfully regenerate, and, ultimately, the disappearance of certain native plant species. "It's not an issue of deer or no deer," Frelich adds. "It is an issue of having a deer population that is in a healthy balance. In a forested area, maybe that's 5 or 10 deer per square mile, not 20 or 30."
That 5 to 10 deer per square mile is becoming a rarer thing in Minnesota. In some of the hardwood forests of north central Minnesota--areas not unlike the ones in Wisconsin where Waller found evidence of ecological wreckage--densities of more than 30 deer per square mile are not uncommon. In some places, they are higher. Near Park Rapids, for instance, there are now an estimated 43 deer per square mile.
The changes wrought by those deer aren't visible only to academics crawling with clipboards on the forest floor. Increasingly, the impact is becoming apparent to many people who make their living in the woods. Last May, Quentin Legler, a consulting forester, had occasion to visit a recently logged 30-acre plot of land north of Grand Rapids. The owner of the property had replanted the field with spruce trees, a food source that whitetails generally eschew. But after a late spring snowfall eliminated most of the other available forage, the whitetails moved in.
In a matter of days, says Legler, nearly all the seedlings in the field had been destroyed. "Some people thought it couldn't have been deer, that it must have been hares," says Legler. "But I know what deer browse looks like and it was deer."
Mike Hauser, a manager with the state's largest private landowner and wood products business, the Potlatch Corporation, has had similar experiences. Where people like Hauser used to spend most of their time worrying about the effects of various plant blights, they now worry about deer. For years, foresters have employed "bud caps"--protective paper covers that are placed on top of seedlings--to keep the peak of the tree from being eaten. That way, even if deer munch on a young tree, the terminal bud will eventually grow high enough that animals will be unable to reach it and the tree will survive.
But as the deer population has grown, this defense has become less effective. "What we've found is that the deer are actually pulling the bud caps off," Hauser says. At a loss, Potlatch and other forestry companies are struggling to find other solutions, such as the use of special deer repellants. So far, however, no solution--aside from replanting--has become evident. And that is expensive. A single acre of seedlings, Hauser says, typically costs between $200 and $300 to replant.
There are some obvious ironies in the struggles of Potlatch and other timber concerns to combat all this damage done by deer. Logging is one of the chief reasons that Minnesota now has so many deer. The widespread use of herbicides on tree farms effectively eliminates many of the understory plants the deer prefer. And by using fertilizers, some researchers believe, the foresters are actually making the seedlings more palatable to the deer.
Most important, however, is what the loggers have done to the landscape. Just as urban design lends itself to growing populations of pigeons, rats, geese, and crows, our management of forest lands has lent itself to a swelled whitetail herd. By transforming vast amounts of Minnesota forest into a virtual aspen plantation--the main species used for paper products--we have created deer paradise.
The blame for this can be spread around generously. The federal government, for instance, has allowed much of Minnesota's two national forests, the Superior and the Chippewa, to be managed for timber and paper pulp harvest. (Dissident Forest Service employees bleakly refer to the Chippewa as the "Chip-away" National Forest). Much of the state- and county-owned land in Minnesota is managed even more intensely for paper pulp harvest.
For the state's half-million deer hunters, this has made for a bonanza. As Mark Johnson, the director of the Minnesota Deer Hunters Association says, "These are the good old days for deer hunting." Hunter success rates--the percentage of hunters who bag a deer during the season--are as high as they have ever been. In some permit areas, as many as 78 percent of hunters last year came home with venison for the freezer.
Predictably, the big deer population has been a reliable boon for the Department of Natural Resources, which collects about $14 million annually from the sale of deer hunting licenses.
Most researchers are quick to acknowledge that they don't yet have a full grasp on how all these deer are affecting the ecosystem. The unknowns are one reason there has not been a systematic, statewide effort to dramatically reduce the size of the herd. As Don Waller puts it, "in general, the absence of data is used to infer an absence of impact."
In Wisconsin, Waller says, many game managers were highly dismissive of his claims that deer constituted an ecological threat. "When I started raising these concerns, I was told that I was alarmist and that the impacts I was seeing were local and temporary," he says. With the accrual of evidence, Waller adds, attitudes there have begun to shift.
At the Minnesota DNR, there is still a reluctance to concede that whitetails are causing much damage to the forests--especially among the agency's employees who work in game management.
Tom Soule, a wildlife coordinator for the DNR in northwestern Minnesota, cautions against applying Waller's research in Wisconsin to Minnesota. "That doesn't mean deer aren't impacting our landscapes, but there's just not much sound data to tell a story," Soule says. "We just have lots of anecdotes."
One area that has received little formal study is the effect that the deer herd is having on other animal species. It is widely acknowledged that the high deer numbers have been a major reason for the successful wolf recovery in Minnesota. And it has also long been known that deer carry a parasitic brain worm that is harmless in whitetails but fatal to other large ungulates, such as woodland caribou, elk, and moose. In Minnesota, the impacts of brain worm on woodland caribou and elk are irrelevant. Caribou have been gone from Minnesota for more than a century, and there just a few dozen elk left in the state.
But there are still about 10,000 moose in Minnesota, mostly in the Arrowhead region in the northeast. For reasons that are not clear, the bearded beasts have gone into decline in the past decade. While the brain worm is not thought to be a major factor, the continued expansion of whitetail into moose country is a hazard to the moose recovery in those areas.
Over the long term, there are suggestions that our growing deer herd will have a deleterious effect on other animals as well, mostly small mammals and various bird species. If the number of white pines in the state continues to decline because of overgrazing by deer, for instance, there will probably be a drop in the bird species like pine warblers that rely on a white pine habitat.
In greater danger may be those birds that dwell in the denuded forest understory. Joann Hanowski, a research fellow with the Natural Resources Research Institute in Duluth, has noted a dramatic decline in ground-nesting birds such as white-throated sparrows and ovenbirds. While there has been little study of the issue, damage to the understory plants by deer is considered one likely explanation.
It is also possible that deer are threatening ground-nesting bird populations in a much blunter manner. Despite Bambi's reputation as a gentle vegan, whitetails are omnivores; their broad palate is a reason they are such an adaptable and successful animal. In the scientific literature, there are accounts of deer feeding on everything from dead fish to shed antlers to nesting birds.
Steve Windels, a terrestrial ecologist at Voyageurs National Park, witnessed this last behavior a few years back while banding songbirds along Hawk Ridge in Duluth. As he approached the mist net--a fine mesh used by researchers to capture birds--Windels noticed a healthy-looking doe and fawn ambling by.
"They were just walking around, foraging," Windels recalls, "and then they came up to the net and munched about half a dozen birds that were caught in it. I was pretty shocked, but they were just being opportunistic."
The whitetail population explosion is also likely having an effect on the health of another large and common animal that lives in Minnesota. Surprisingly, it is an area of inquiry that has received little attention to date. What is known is this: More and more Minnesotans are becoming infected with Lyme disease after being bitten by deer ticks. In 2002, according to the Minnesota Department of Health, there were a record 867 cases of Lyme disease in the state. While the ticks don't pick up Lyme disease from the deer--the white-footed mouse first infects the parasites--deer do play a vital role in the life cycle of the tick. In the second year of life, the adult ticks live and mate on the deer.
Is it a coincidence that the rising incidence of Lyme disease and other tick-borne illnesses such as ehrlichiosis has been accompanied by a spike in the deer population? In Minnesota, the matter has not been explicitly studied. But in the northeast states, where 90 percent of Lyme disease cases occur, researchers have linked the prevalence of Lyme to the expanding population of white-tailed deer. Studies have shown that 95 percent of adult female deer ticks feed on whitetails.
Does that mean that a reduction in the deer population in Minnesota might reduce the incidence of Lyme disease? The verdict is out--in part, because no one is yet asking the question.
There is nothing "natural" about the deer herd anymore. In Minnesota, where deer hunting is something of a cross between religion and big business, this central fact has received precious little attention. For decades, the Department of Natural Resources has viewed deer hunters as one of its most important constituencies. Befitting that view, the agency has managed the hunting season with an eye toward maximizing the population.
Historically, this has been achieved mainly by two means: a relatively short season and an emphasis on a bucks-only harvest. By prohibiting the killing of does, the DNR effectively ensured that there would always be a large population of breeders--and plenty of attractive targets for hunters the next fall.
Over the past five years, as the implications of such an outsize deer herd have grown harder to ignore, the DNR has begun to liberalize hunting regulations. In some "intensive harvest" permit areas, hunters can take as many as five deer in a season. Doe permits, once issued exclusively by lottery, are relatively easy to get in many parts of the state. And yet the population keeps swelling; the loop is out of control.
Hunters, unlike their quarry, have been slow to adapt to the new conditions. Though more hunters today are willing to take a doe, the culture of the hunt remains fixated on the buck. If you check the covers of deer-hunting magazines, you will rarely see a doe pictured. The image, instead, is almost always a buck, usually with an enormous antler rack and a neck engorged from the hormonal rush of the rut.
Shooting a big buck may make the hunter feel more virile, but it does little to control the deer population, as a single surviving buck can breed with multiple does. From a population-management point of view, the most effective way to cut the numbers would be to require hunters to shoot at a doe before taking a buck. In Wisconsin, the DNR has experimented with a program along such lines called "Earn a Buck."
But while the Minnesota DNR considered such an option, says big game coordinator Lou Cornicelli, hunter resistance has kept the agency from embarking on the experiment.
Ecologically speaking, deciding that Minnesota needs to foster deer habitat is roughly akin to the mayor of Minneapolis declaring that the city needs to create more pigeon habitat. Yet that remains a central creed among deer hunters. The Minnesota Deer Hunters Association sponsors a program called "Hides for Habitat" that raises money through the sale of deer hides for habitat projects. Land-owning hunters plant special seed blends designed to appeal to deer: high-protein greens like clover, along with oats, wheat, and rye. And during harsh winters, many Minnesota hunters--worried that their quarry will starve--take to the woods to deliver bags of corn and hay. (These practices sometimes backfire, as the starving deer, like a starving man at the buffet, sometimes overeat and succumb to a fatal bloat.)
Season after season, hunters wield their considerable political influence to ensure that the DNR continues to manage the herd in a way that is most likely to put venison steaks in the freezer. Even the nonhunting public plays along. In the metro area, efforts to control the burgeoning suburban deer herd often meet howls of protest. When archers began thinning the herd at the Minneapolis Water Works in Columbia Heights, neighbors cried slaughter--never mind that the deer are so grossly overpopulated as to face the prospect of starvation.
When I killed that big doe with my car five years ago, I felt remorse and repulsion. It was not just the suffering of the animal that bothered me. It was the feeling that I was just another human tipping the scales against the animal kingdom, as is our way.
But I was foolish to mourn. At this moment in history, whitetails are pretty much everywhere. They have expanded their range to all of the lower 48 states, eight Canadian provinces, all of Central America, and much of the northern parts of South America. Transplanted whitetails have successfully established populations from Finland to Cuba to Bosnia. In New Zealand, 50 transplanted whitetails took to the range with such success that game managers there eventually did away with any hunting limits. Yet even in the face of regular hunting and natural predation, whitetails can double their populations in two years.
By any rational measure they are a "weedy" species--a creature that directly benefits from the ways we have altered and despoiled the land. As the writer David Quammen points out in "Planet of Weeds," a definitive eco-apocalyptic essay that appeared in Harper's magazine a few years back, the weedy species are taking over the world's ecosystems. We are living in a time of mass extinction, marching toward monoculture, entering a world of infinitely less variety and interest than the one we were all born into. The whitetail--in its current numbers and distribution--is a manifestation of that.
There is a feedback response in ecosystems. With the disappearance of each obscure little plant or rare bird, there is often a corollary effect known as co-extinction. The spotted owl vanishes as the old growth firs fall to the axe; a rare vine in Singapore goes extinct and the island's prettiest butterfly soon follows. And then, at some point, entire ecosystems begin to falter. We are left with the weeds.
What happens next is an open question. Perhaps some other opportunistic form of life--a disease or a blight--emerges and exploits the overpopulated species. As epidemiologists have long recognized, there is a clear relationship between population densities and infectious disease. That is why farmed animals such as cows, pigs, and chickens must be pumped full of antibiotics; it's why TB outbreaks among human beings tend to occur in cities and prisons.
The whitetails of the Great Lakes states seem ripe for a plague--if it's not here already. In 2001, chronic wasting disease (CWD)--a mad-cow-like prion scourge that is endemic among the elk of the mountain West states--struck Wisconsin's deer herd. Not surprisingly, the first cases were found in an area near Madison, where the deer densities are exceptionally high. Given the current whitetail numbers in Minnesota, some scientists think it is strictly a matter of time before chronic wasting disease emerges here.
That prospect has caused plenty of alarm among hunters and nonhunters alike. But maybe CWD, or some other plague, might not be such a terrible thing after all. Disease, in its ugly way, may do what we collectively have been unable or unwilling to do: restore a natural balance.
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