"Though deer are becoming almost as ubiquitous in the suburbs as squirrels and rabbits, there is a great deal that biologists and wildlife managers don't know about how they dwell among us. Ferebee's effort is part of a wave of inquiry: How do deer understand human activity, navigate traffic, reproduce in populated areas? Are they becoming, in some fundamental way, a different animal than deer living in the wild?
Deer are highly adaptable animals, equipped with slender but muscular legs, and cloven hooves that allow them to easily leap and balance. They are a browsing species, capable of eating a huge variety of vegetative matter, which they digest in their four-chambered ruminant stomach.
"Deer are like--I compare them to goats; they can eat almost anything and it won't hurt them," Doug Tregoning, a University of Maryland extension agent, says at a Montgomery County Sierra Club meeting for homeowners weary of deer laying waste to their yards. The session is held at Brookside Gardens in Wheaton, which, Tregoning says, installed a state-of-the art deer fence only to discover that deer figured out how to enter through a spot where a stream ran underneath. Tregoning provides homeowners with lists of plants that deer dislike, but when he mentions chrysanthemums, a woman's hand shoots up. "Excuse me! They ate mine! Just trimmed off the flowers and left the plants!"
And though they look vulnerable with their wide eyes, soft noses and graceful necks, they are anything but fragile. "It takes a lot to kill a deer," says Earl Hodnett, a wildlife biologist who until recently worked for Fairfax County police and now works for USDA. "Deer are very tough animals. The dead deer that we see on the side of the road--in order for that to happen, the deer's back or neck has to be broken. Otherwise, even if they're mortally injured, they'll make it into the woods."
In Fairfax County, at least 5,000 deer-car collisions occur annually, an estimate based on the fact that 1,300 to 1,400 deer carcasses are retrieved in the county by the Virginia Department of Transportation; studies show the number hit is usually exponentially higher. Deer can live with severe injuries.
"I've got a deer in my yard that I see frequently that has three legs," says Hodnett. "He's missing one front leg below the knee. That leg used to just dangle, but eventually wrung itself off, and he's just got a callused nub on the end. I've seen him run. He is not handicapped."
While layers of local, state and federal deer bureaucracies try to "manage" their numbers, the deer are busy figuring out how to take evasive action. We may be driving their evolution, creating a deer that is not only attracted to suburban areas, but adapted to live easily within them. Already, the urban or suburban deer is "a different creature than we find walking about in rural areas," says Steve Ditchkoff, an associate professor of wildlife biology at Auburn University.
Deer are a crepuscular species, for example -- they emerge to feed at dusk and dawn. But deer in developed areas appear more nocturnal, bedding down during the day and coming out at night. As long as they avoid being hit by cars, their life spans can be longer than deer in huntable populations, many of whom do not live beyond four or five years. And they may be more fertile: Does typically give birth to twins, but well-fed suburban deer have been known to produce triplets.
Even as they remain largely mysteries to us, deer have become intimately familiar with our habits. Biologists say they come to anticipate the times when garbage is picked up, when school buses stop, when dogs are walked, when human beings return from work -- and adjust their habits accordingly. The thickets and green spaces of suburbia become refuges from which deer can observe our behavior.
"Remember what deer do for a living," Ditchkoff says. "They stay alive. That's what they're designed to do. They are a prey species. There's always something trying to eat them. If the predator is a dog, or human disturbance, they're going to learn those patterns. You can go walking through some little creek bottom, through a neighborhood, and be 15 feet from a deer bedded down. It may be watching. You won't see it.
The success of white-tailed deer is a classic tale of unintended consequences. Before the advent of European settlers, deer were plentiful in North America. Native Americans hunted them, as did cougars and other large predators. Colonists, when they came, did the same and traded pelts to Europe. Later, market hunting -- killing deer to transport their meat to American cities -- severely reduced their numbers. Until the 20th century there was little in the way of game laws. "People thought, We'll never run out of game," says George Timko, an assistant deer project leader for Maryland's Wildlife and Heritage Service.
By the early 1900s, though, deer were almost extinct in many parts of the country, including Maryland and Virginia. States enacted hunting restrictions, even moratoriums. Biologists relocated deer from areas where they were still plentiful to areas where they had dwindled. Nobody foresaw how resoundingly the effort would succeed. "We didn't know that deer were so adaptive," Timko says. "We thought they'd be confined to the rural areas and the agricultural areas in the state. We never thought that deer would be living in cul-de-sacs."
Timko takes a drive around the South Mountain area in Maryland's Frederick and Washington counties, contemplating the other factor that contributed to the deer renaissance: the rise of the American suburb.
Deer are what's known as an edge species. They can exist in many environments, but they prefer boundary regions between woods and grasslands. The deep center of a mature forest is not ideal for deer. They do better at the edge of a forest, where sunlight and ground vegetation are abundant, and where they can venture to browse in the open but retreat easily into cover. And what is suburbia but edge? Little patches of forest that give way to lovely little patches of fertilized grass, ringed with tasty daylilies?
In fact, it may be exurbia -- sprawl -- that caused the deer population to explode, particularly in places with large houses on one-, two- or 10-acre lots. The typical exurban subdivision is a ready-made deer park. A single property may contain woods, water and lawn, everything a deer needs for cover and comfort. And it may be the skyrocketing number of deer in exurban areas that is propelling them into the city. Ken Ferebee says officials in Rock Creek Park suspect it was the development of Montgomery County that prompted deer to migrate down the Rock Creek valley. "The numbers of deer have become so high in these newer-style suburban areas, they're almost forced to come into" older neighborhoods, says Auburn's Steve Ditchkoff.
In these environments, deer create conflict just by living their normal lives. Much of a deer's existence is driven by the seasons and the reproductive cycle. Throughout the summer, bucks grow antlers, which are fed by capillaries and covered with furred skin called velvet. The point of antlers is to intimidate other bucks and impress does during mating season.
By August, antlers have reached their mature size, and the bucks rub off the velvet by scraping their antlers against trees, making gashes in the bark. Beginning in October, the rut -- bucks chasing does, sometimes for miles -- creates a surge in car collisions. In the late spring and summer, when fawns begin to follow their mothers, there will be another spike in accidents. And some homeowners in areas with high deer concentrations, such as Cub Run Stream Valley in Fairfax County, attribute a surge in Lyme disease cases to the number of deer.
And then there is their impact on the landscape. Here around South Mountain, Timko points out exurban properties where homeowners are trying to tame the forest -- planting trees, shrubs and vegetable gardens in what used to be a heavily wooded area, and resorting to every possible means to keep deer away. He drives by a clutch of Leyland cypresses protected by a rope fence; a walnut orchard with tubes around the trunks. Then he comes upon an example so stark he uses it in PowerPoint presentations to garden clubs and homeowners associations: a house whose owners attempted to line the driveway with a row of American yews that have been chewed so thoroughly that they look like lollipops.
And it's not just individual landowners who are seeing their flora endangered. In the South Mountain area, where deer number as many as 45 per square mile, they inflict catastrophic damage to local forests, denuding them of future growth. Timko stops at a patch of woods to show the impact: a "browse line," below which there is little vegetation. A mountain laurel has been eaten to the point where there are leaves only at the top. On the forest floor, an oak seedling has been stripped of early shoots. Deer will nibble the shoots until the plant loses the energy to grow. The result is a "dead forest that will not replace itself," Timko says, and can't provide shelter for songbirds and other wildlife that depend on cover. Environmental groups such as the Sierra Club are increasingly alarmed by the devastation deer are wreaking on the landscape.
Homeowners' growing ambivalence is easy to see in the South Mountain area. As Timko drives, he points out houses whose occupants keep feeders stocked with corn to attract deer to their yards. They either don't realize, or don't care, that they may be encouraging deer to cross residential streets to get to the feeders, endangering the deer as well as motorists. Elsewhere are the houses with ravaged shrubbery, sometimes directly across from a house with a feeder, a juxtaposition guaranteed to fuel discord. Timko and other government biologists spend a lot of time acting as peacekeepers, meeting with people exasperated by the deer or people exasperated with their neighbors for feeding the deer.
Highly social animals, deer congregate not in herds but in small matrilineal groupings dominated by a female. In the second year of a buck's life, his mother will evict him, a process that helps prevent inbreeding. Depending on the time of year, the males will travel alone or clump loosely together. The doe hangs out with her daughters, who may drift when they have fawns of their own, but never far away.
Creatures of habit, deer have home ranges, patches of landscape they know intimately. Bucks can have a wide range; bucks that were ear-tagged in Gaithersburg have been found in Fairfax County. (Deer are very competent swimmers, particularly in winter, when their hairs are hollow, a quality that provides insulation but also buoyancy.) Does usually spend their lives within a fairly small area, and studies have shown that if they're driven from their home range, they will invariably return.
And they can populate that home range quickly, thanks to the doe's tendency to have twins and, when well fed and healthy, triplets. (If she is malnourished, she may only have one, and can even re-absorb the fetus during pregnancy.) Owing to this fecundity, it's possible for a deer population to double annually.
Studies have shown that they have the capacity to learn. Or some do.
Biologists are not sure how deer understand vehicular traffic. They proverbially freeze when they see headlights, not necessarily because they know a car can crush them, but more likely because noise and lights signal danger. One study found that given the opportunity to cross a road safely using a special culvert, deer will seize it.
"They adapt," says Southern Illinois' Clay Nielsen, who thinks car-savviness is one way suburban deer may differ from their rural counterparts. "They learn to cross roads in areas that minimize their mortality . . . Some deer have the ability to learn and some don't, and those that don't, die . . . They have not evolved knowing what a car is, or knowing how to avoid cars and vehicles in the landscape. They are trying to learn."
And, he adds: "These are the ones that are surviving and passing along their genes and learning how to thrive in the urban landscape."
Liza Mundy is a Magazine staff writer.
Timko takes a drive around the South Mountain area in Maryland's Frederick and Washington counties, contemplating the other factor that contributed to the deer renaissance: the rise of the American suburb.
Deer are what's known as an edge species. They can exist in many environments, but they prefer boundary regions between woods and grasslands. The deep center of a mature forest is not ideal for deer. They do better at the edge of a forest, where sunlight and ground vegetation are abundant, and where they can venture to browse in the open but retreat easily into cover. And what is suburbia but edge? Little patches of forest that give way to lovely little patches of fertilized grass, ringed with tasty daylilies?
In these environments, deer create conflict just by living their normal lives. Much of a deer's existence is driven by the seasons and the reproductive cycle. Throughout the summer, bucks grow antlers, which are fed by capillaries and covered with furred skin called velvet. The point of antlers is to intimidate other bucks and impress does during mating season.
By August, antlers have reached their mature size, and the bucks rub off the velvet by scraping their antlers against trees, making gashes in the bark. Beginning in October, the rut -- bucks chasing does, sometimes for miles -- creates a surge in car collisions. In the late spring and summer, when fawns begin to follow their mothers, there will be another spike in accidents. And some homeowners in areas with high deer concentrations, such as Cub Run Stream Valley in Fairfax County, attribute a surge in Lyme disease cases to the number of deer.
And then there is their impact on the landscape. Here around South Mountain, Timko points out exurban properties where homeowners are trying to tame the forest -- planting trees, shrubs and vegetable gardens in what used to be a heavily wooded area, and resorting to every possible means to keep deer away. He drives by a clutch of Leyland cypresses protected by a rope fence; a walnut orchard with tubes around the trunks. Then he comes upon an example so stark he uses it in PowerPoint presentations to garden clubs and homeowners associations: a house whose owners attempted to line the driveway with a row of American yews that have been chewed so thoroughly that they look like lollipops.
And it's not just individual landowners who are seeing their flora endangered. In the South Mountain area, where deer number as many as 45 per square mile, they inflict catastrophic damage to local forests, denuding them of future growth. Timko stops at a patch of woods to show the impact: a "browse line," below which there is little vegetation. A mountain laurel has been eaten to the point where there are leaves only at the top. On the forest floor, an oak seedling has been stripped of early shoots. Deer will nibble the shoots until the plant loses the energy to grow. The result is a "dead forest that will not replace itself," Timko says, and can't provide shelter for songbirds and other wildlife that depend on cover. Environmental groups such as the Sierra Club are increasingly alarmed by the devastation deer are wreaking on the landscape.
Homeowners' growing ambivalence is easy to see in the South Mountain area. As Timko drives, he points out houses whose occupants keep feeders stocked with corn to attract deer to their yards. They either don't realize, or don't care, that they may be encouraging deer to cross residential streets to get to the feeders, endangering the deer as well as motorists. Elsewhere are the houses with ravaged shrubbery, sometimes directly across from a house with a feeder, a juxtaposition guaranteed to fuel discord. Timko and other government biologists spend a lot of time acting as peacekeepers, meeting with people exasperated by the deer or people exasperated with their neighbors for feeding the deer.
Highly social animals, deer congregate not in herds but in small matrilineal groupings dominated by a female. In the second year of a buck's life, his mother will evict him, a process that helps prevent inbreeding. Depending on the time of year, the males will travel alone or clump loosely together. The doe hangs out with her daughters, who may drift when they have fawns of their own, but never far away.
Creatures of habit, deer have home ranges, patches of landscape they know intimately. Bucks can have a wide range; bucks that were ear-tagged in Gaithersburg have been found in Fairfax County. (Deer are very competent swimmers, particularly in winter, when their hairs are hollow, a quality that provides insulation but also buoyancy.) Does usually spend their lives within a fairly small area, and studies have shown that if they're driven from their home range, they will invariably return.
And they can populate that home range quickly, thanks to the doe's tendency to have twins and, when well fed and healthy, triplets. (If she is malnourished, she may only have one, and can even re-absorb the fetus during pregnancy.) Owing to this fecundity, it's possible for a deer population to double annually.
Studies have shown that they have the capacity to learn. Or some do.
Biologists are not sure how deer understand vehicular traffic. They proverbially freeze when they see headlights, not necessarily because they know a car can crush them, but more likely because noise and lights signal danger. One study found that given the opportunity to cross a road safely using a special culvert, deer will seize it.
"They adapt," says Southern Illinois' Clay Nielsen, who thinks car-savviness is one way suburban deer may differ from their rural counterparts. "They learn to cross roads in areas that minimize their mortality . . . Some deer have the ability to learn and some don't, and those that don't, die . . . They have not evolved knowing what a car is, or knowing how to avoid cars and vehicles in the landscape. They are trying to learn."
And, he adds: "These are the ones that are surviving and passing along their genes and learning how to thrive in the urban landscape."
Liza Mundy is a Magazine staff writer.
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