getting wild in the city
.

Cats kill birds

Deer destroy plants

Raccoons deal death



 


1992 (right): When culling began in Du Page County Forest Preserves, deer had devoured the ground-level vegetation outside the fenced "exclosure" at the center, which deer cannot enter.

scene in 1994
1994 (above): Two years after shooting began, vegetation is recovering outside the exclosure.

scene in 1998
1998 (above): Vegetation is almost as dense outside the exclosure as inside.

Courtesy of Daniel Ludwig, Forest Preserve District of Du Page County, Ill.

.

Doggone deer
Who could hate a white-tailed deer? Nobody who's seen the movie version of Bambi, at any rate. But in cities and suburbs, Bambi and Co. are gobbling up azaleas, tulips and other garden goodies. In woodlands, they are devouring native trees and shrubs and wildflowers, literally changing the composition of forests.

scene in 1992

In both areas, hundreds of thousands of deer are being hit by cars each year.

The suburban deer problem can start rather pleasantly. "People are enamored by deer early on," says William Porter, a professor of wildlife ecology at State University of New York in Syracuse. "It's quite something to see a deer eating in your yard. But with each year there are a few more deer, and eventually there aren't any tulips left, the shrubs are gone, and you can't seem to grow anything, even if it's fenced."

You've come a long way, Bambi
Fifty years ago, the problem with white-tailed deer -- in many of the areas where they're now so common -- was absence, not abundance. The animal's remarkable comeback reflects the rise of good deer habitat, like the grass, ornamental shrubs and gardens in cities and suburbs. It also reflects the success of poaching laws and the increasing proportion of dogs that are leashed. Simple mathematics also plays a role: When dogs kill a few deer from a low population, that limits their population. After a population boom, a few deaths are trivial.

In suburbs and urban fringes, deer densities have reached 100 to 200 per square mile, 5 to 10 times higher than most rural habitats. Unless checked, deer populations will expand until the number of fawns born each year equals the deaths to disease and malnutrition -- the so-called "ecological carrying capacity."

High densities of deer run up against the top dog in the landscape -- us. As collisions with cars and damage to vegetation increase, some homeowners start squawking. Can't somebody do something to control the deer?

Animal lovers sometimes interpret this demand as a request for an extermination campaign, and the battle lines are drawn. "The community gets polarized pretty quickly," Porter says. "Some people want to do something dramatic, but there are people who say 'Absolutely not. They're beautiful, and they have rights.'"

With no easy solutions at hand, a bitter confrontation can ensue.

Ticket to ride
An early response to the deer-overpopulation problem was the moving van. In the 1980s, for example, when deer numbers exploded in River Hills, Wis., authorities relocated up to 100 deer per year to the countryside. The program ground to a halt after scientists figured that 83 percent of the evacuees had been killed by cars or hunters within a year, compared to 17 percent of deer who stayed behind (see page 165 of "Hearts and Blood" in the bibliography).

Relocation programs are also expensive -- costing $400 to $2,931 per animal, and they often simply shift the overpopulation problem to wherever the animals are dumped.

In light of these drawbacks, advocates of non-lethal control began considering birth control. Today's most promising technique, immuno-contraception, causes the does to mount an immune reaction to a protein on the surface of their egg cells. The reaction kills the egg, preventing pregnancy.

Unfortunately, since the contraceptive would be destroyed in the gastrointestinal system, it must be given by injection. That entails shooting does with a dart from close range at least once a year. While the small percentage of relatively tame does are easy to hit, it's difficult to dart the reclusive ones.

Although the exact cost depends on the situation, Porter says contraception is generally much more expensive than shooting. For one thing, shooting reduces the actual number of animals, while contraception merely limits their increase. Shooters can also work from a greater distance. And dead animals won't need contraception next year.

Shoot to kill
Despite the general squeamishness about shooting helpless deer, Porter says, "When you tell [cities and suburbs] that non-lethal control will cost big bucks" (honest, these are his words!), shooting often becomes the chosen control option.

Shooting should not be confused with hunting. The idea is not to give the deer a chance, but to shoot them in the head from close range, so they die quickly and with relatively little suffering.

In these so-called "culling" operations, sharpshooters typically await deer in a blind above a bait station. "It's a high-powered rifle, the bullet can travel a considerable distance in a straight line," says Daniel Ludwig, an animal ecologist with the Forest Preserve District of Du Page County, Ill. (that's near Chicago). "You guarantee that if the animal is not hit, the bullet will go into the ground."

Ludwig says the district has been shooting deer since 1992 in about 10,000 acres of forest preserves. He sees no viable alternatives. "Contraception is still being developed, but multiple doses are needed. When you have animals at such high densities [at one point 100 per square mile], you have to reduce the numbers. For us, the most cost-effective technique is sharpshooting."

Shooting seems to be working in Du Page County. The groundcover is denser, and more rare plants -- the ones deer prefer -- are returning. By shooting deer, the forest preserve district appears to be preserving the forest.

Still, shooting is controversial. Instead of joining the "deer haters," wildlife managers should teach people to get along with deer," wrote Allen Rutberg, senior scientist at the Humane Society of the United States. "I encourage wildlife professionals and wildlife advocates of all stripes to join with animal protectionists and others to help raise the public threshold of acceptance of wildlife and perception of overabundance." Rutberg argued that wildlife is increasingly dependent on humans, and if we don't learn to get along, we'll just be destroying more of our world's living endowment (see pp. 520-3 of "Wildlife Society Bulletin" in the bibliography).

In the future
That returns us to the question: How can we control deer humanely but affordably?

Better contraception Tests continue on better and cheaper ways to deliver contraceptives.

Smarter contraception Even if contraception remains expensive, it may be useful in some situations. Porter notes that studies of deer behavior show that females "are glued to the place where they were born." Theoretically, you could control the population in a neighborhood by darting enough females with contraceptives, knowing that other does would remain at home.

Changing habitat The availability of habitat helps determine the abundance of any animal, and a key reason for the glut of deer is the boom in deer delis -- suburban lawns and gardens. Could changing habitat reduce deer numbers? Porter says it's a good question, and while too little is known about deer behavior in urban areas to answer it, landscape architects and wildlife scientists have begun developing community designs to "minimize the conflicts between deer and people." Ultimately, he adds, habitat management is "probably the only cost-effective way" to manage deer.

In the meantime, until a cheaper, smarter method is invented, shooting will likely remain the tactic of choice in deer control. Expect the controversy to continue as rising deer populations butt up against mushrooming suburbs.

Revealed: the downside to raccoon life cycle.


back more
The Why Files
.
There are 1 2 3 pages in this feature.
Bibliography | Credits | Feedback | Search

©1999, University of Wisconsin, Board of Regents.