On Science: Bambicide in West County: Dealing with exploding deer population
This article first appeared in the St. Louis Beacon, Sept. 30, 2009 - I was 14 when I shot my first deer. I was standing next to a large gray tree, shivering, early on a cold November morning. I had been left alone there on my "stand" by my father two hours previously, in the darkness just before dawn. I was lonely and a little scared, the gun uncomfortably heavy in my arms. Every sound I heard could be, to my excited imagination, an approaching deer. After two hours, I was a nervous wreck. Then, suddenly, one of the sounds WAS a deer, with horns, running through the trees not very far in front of me.
I raised the gun and fired once, very fast. No aiming was involved, just nervous reaction. That was one unlucky deer. The bullet, unaimed, found its way right to the deer's heart. I put down the gun and walked over to the body of the deer I had killed. His eyes were still open, his fur warm. I have never, and will never, pick up a hunting gun again.
In the absence of my hunting, the national deer population has exploded. Early in the 20th century, white-tailed deer were rare in the Midwest. Uncontrolled hunting had reduced their numbers to about 500,000 nationwide, and some states had no deer at all.
To protect the remaining deer, laws were past in the 1920s and '30s to restrict hunting, particularly of does (females). This course of action seemed sensible, but ignored a fundamental fact about deer: Deer reproduce quickly. A doe matures at 2 or 3 years, and then typically gives birth to twins each year for 10 or more years.
Any student of biology could have predicted what would happen, what would HAVE to happen, if hunting were severely restricted. Since Malthus and Darwin, biologists have recognized that populations that grow unchecked do not increase in a linear fashion, but exponentially. That is to say, the population does not increase the same amount each year, but rather grows by ever-greater amounts as the babies have babies, like compound interest.
A deer herd that has plenty to eat and is not hunted by humans or other predators will double in size every three years!
With the restrictions on hunting, deer populations indeed began to grow. Numbers of white-tailed deer rebounded slowly at first, then more and more quickly. In the past few decades, deer numbers have literally exploded, and now exceed 30 million nationwide. There are more deer today in Missouri (an estimated 900,000) and Illinois (an estimated 750,000) than at any time in our nation's history.
Much of the growth in the national deer population has occurred in the last few decades, much of it near urban areas. Deer have adapted well to encroaching suburbia, for two reasons:
1. Growth of suburbs. Paradoxically, land development tends to improve deer food supplies. Because the reproduction and survival of deer depend directly upon the quality of the food available to them, the improved food has led to more deer. Deer browse on leaves, and require large quantities of new growth with high nutritional content to maintain normal reproduction. Deer populations 40 years ago rarely grew large for the simple reason that most of the trees in an undisturbed forest are old, and only the undergrowth provides suitable food. Because land development usually involves clearing land, urban development leads to increased deer food supplies. There are far fewer trees, but the trees are new growth, and very munchable. So are garden shrubs. Deer eat very, very well in suburbia.
2. Restriction of hunting. Nobody wants someone shooting at deer near their kids. Not surprising, then, much of the area in which deer populations are growing most rapidly have been declared off limits to hunters. Removing their only significant predator -- hunters -- allows deer populations to grow unchecked.
Anyone who lives in the western parts of St. Louis County, or anywhere else in the suburbs surrounding St. Louis, knows the result of providing ample food and no hunting: lots of deer. "A deer in the backyard is wonderful," says wildlife biologist William Porter. "Twenty-five deer in the backyard is a problem." Nancy Hoffstetter of Town and Country has been quoted as saying "I consider them long-legged rats."
What should we do to respond to this plague of deer? You can't just "remove" the deer to some forest far from St. Louis, as they set out to do a decade ago in Town and Country at an initial cost of $360 a deer. Why doesn't this humane approach work? Other St. Louis deer from surrounding areas just take their place!
Imagine trying to empty people from a prime section of our new baseball stadium by physically removing individuals one at a time. You would never get anywhere, because other people would just crowd in. For every deer removed from Town and Country, there are two eager to get in and have a good meal. Nevertheless, Town and Country has been continuing its deer relocation plan, year after year, and year after year other deer have been refilling the emptied slots in the chow line. This past week, Town and Country chose a different path.
There were only two real options open to them: decrease the birth rate or increase the death rate.
Decreasing the birth rate is certainly the most ethically palatable approach. However, deer birth control has proven impractical. Every female deer must be captured for the first dose, and redarted for each subsequent booster shot. Only in very small isolated populations is this practical. Nor is there any effective oral contraceptive for deer.
This leaves increasing the death rate. On more remote forest land, I have written often that Missouri should extend the hunting season, increase the bag limit, and encourage the shooting of antlerless females. But there is no hunting in Town and Country, and no one there wants there to be.
In suburbs like Town and Country, the only realistic approach is to thin out the local herds with professional sharpshooters, and that is precisely the deer control approach Town and Country adopted this week. Deer will still be safe in your backyard, but the herd will be culled by taking deer from open fields of ten acres or more.
No one wants to kill Bambi, but Bambi starving to death is every bit as unpleasant an option, and if the St. Louis deer herd continues to grow, that is what is going to happen. A lot more deer will die, a lot more miserably. Town and Country, after a decade of trying to avoid this unpleasant but regrettably necessary policy, is doing exactly the right thing. I congratulate them, and hope Wildwood and the other West County suburbs follow their lead.
So, as deer hunting season approaches, I find to my surprise that the same ethical pain that caused me to abandon hunting as a teenager now compels me to urge the shooting of more deer today. It is not an easy choice, but I think it is the right one.
George B. Johnson's "On Science" column looks at scientific issues and explains them in an accessible manner.
Johnson, Ph.D., professor emeritus of Biology at Washington University, has taught biology and genetics to undergraduates for more than 30 years. Also professor of genetics at Washington University’s School of Medicine, Johnson is a student of population genetics and evolution, renowned for his pioneering studies of genetic variability. He has authored more than 50 scientific publications and seven texts.
As the founding director of The Living World, the education center at the St Louis Zoo, from 1987 to 1990, he was responsible for developing innovative high-tech exhibits and new educational programs