Why ecologists support Ann Arbor’s deer cull

In her recent guest column, Tanya Hilgendorf of the Humane Society of Huron Valley wrote that Ann Arbor’s deer cull was part of a “‘Green Scare’ put forward mostly by those who, under an ‘ecological’ guise seek to eradicate any plant or animal not currently in popular favor.”

I have discussed the urban deer issue with academic biologists at the University of Michigan, including ecologists, botanists, zoologists, restoration ecologists and landscape architects. We are all in support of city council’s decision to conduct a cull.

Ann Arbor’s high deer abundance is part of a much broader phenomenon. In the past 100 years whitetail deer numbers have swelled to historic highs across their range. Deer overabundance poses a threat to many North American ecosystems.

Consider that a single whitetail selectively consumes roughly 3,000 lbs. (1.5 tons) of plant material each year. Herds remove swaths of forest wildflowers and damage the woody understory. This impacts native butterflies, bees, small mammals, amphibians and certain birds. Whitetails alter forest composition by browsing oak and other hardwood seedlings. Their food preferences allow unpalatable species to proliferate, including invasive garlic mustard and Japanese barberry, which inhibit the next generation of forest trees and native wildflowers.

Deer are present in even higher abundance in urban settings. City parks and suburban gardens are rich in preferred food. The deer are safe from hunting and natural predators. They can wander through lawns and along roads in broad daylight. They habituate to humans and become a nuisance to many residents.

Critics of the cull demand more details. How many deer are too many? What about non-lethal methods? Do culls even work? These are important questions.

Opposing view: Are Ann Arbor’s deer enough of a threat to warrant firepower?

From ecological and conservation perspectives, an ideal deer herd will coexist with a full range of native species. By several measures, Ann Arbor’s herd size has surpassed this threshold. Botanists at the U-M have long noted declines in native plants that deer favor, through decades of observation, and by comparison with landscapes where deer are excluded or managed. In a 2015 study, an ecological team surveyed browsing impacts in Ann Arbor’s Bird Hills Nature Area. They found browsing damage in 80 percent of the tree saplings.

For more than a decade, the Humane Society of the United States has inserted itself into urban deer conflicts and lobbied for non-lethal methods of deer control, including contraceptive drugs and surgical sterilizations (note, the Humane Society of Huron Valley is not funded by nor affiliated with the national group). City council has agreed to consult with the Humane Society of the United States on non-lethal methods in coming years.

Contraceptive drugs for deer are illegal in Michigan and difficult to administer. Surgical sterilization is an expensive ($1000 per deer) and invasive procedure. Both approaches are ineffective for controlling free-ranging herds.

For evidence that culls help to restore ecological balance and biodiversity, we can look to the University of Michigan’s ES George Reserve. In 1928, four does and two bucks were released into the 1300-acre research tract. The population rose from six to more than 160 animals in six years, creating heavy browsing pressure and suppressing plant succession. Since 1942, reserve stewards have periodically culled the herd, with a steady recovery of oaks, hickories, maple and other native species.

Apart from its ecological value, deer culling is an important tool for combatting emergent diseases. These include deer Chronic Wasting Disease and Lyme disease. Lyme disease causes life-debilitating symptoms in people (and pets) and is associated with high deer density.

The Ann Arbor deer cull may not reverse decades of ecological degradation or prevent all diseases. But with around 150 tons of buds, leaves and flowers that will be spared this year alone, it is a positive step toward ecological sustainability.

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Margaret Leary
Thu, 01/14/2016 - 9:49am
I wonder whether BRIDGE could put an equally prominent link from Ms. Hilgendorf's "opposite opinion" in BRIDGE to this one, to provide balance to both rather than highlighting only Ms. Hilgendorf's?
David Zeman
Thu, 01/14/2016 - 11:37am
Hi Margaret, The column actually links TWICE to the opposing article: There's a hyperlink to it in the first first sentence of this column, and there's a second link below the sixth paragraph. David Zeman Bridge Editor
Bob G.
Sun, 01/17/2016 - 4:57pm
David, I think Margaret meant she'd like a link from the anti-cull commentary back to this one so that anyone reading that piece would be able to easily get to this one -- which is there after the fifth graf in her piece.
Robert S
Thu, 01/14/2016 - 9:50am
I used to think that Ann Arbor used to be the home of 'brains.' No more. There is a simple fix to keeping the deer out of your gardens. They sell at garden stores and you can even make the mix yourself. It is nothing but eggs and water in a bucket. The smell is horrible and the deer don't like it at all. I have used it at my home for several years and the deer stay away from us and our gardens thrive. Wake up Ann Arbor! There is a simple solution to what has become a complex, divisive issue.
Thu, 01/14/2016 - 12:07pm
The deer are eating stuff w/ deer off sprayed on it. Tried multiple versions, store bought and home made; they are eating things they don't like because they are starving because they ate all the stuff they do like.
Thu, 01/14/2016 - 12:34pm
great that they stay out of your yard, but then eat up important plants in the Arb, and run into the road to be hit by cars. I live right on Washtenaw and was amazed to see 6-8 deer meander across the street to eat in my yard. I've done the repellent "fix" and tried to use less "attractive" plants, but these animals are very hungry or they wouldn't range the way they do. Saw skeletal herds in the Arb last spring.
Eve Brown
Mon, 01/18/2016 - 11:25am
Did you read the suggested article? it suports the idea that the deer 'problem' is not just an individual 'keep my yard/garden- deer free'. This is a serious multi issue regional problem.
Bill Yocum
Mon, 01/25/2016 - 11:58am
I grew up next to Bird Hills Park and wonder if the fellow who suggested deer repellant as an overbrowsing solution has ever been there? Deer were not common there in the '60s. Now they bed down in the back yards of adjoining homes during the day when there is typically more park use and the homeowners are at work. Ann Arbor decision makers should pay heed to Professor Dick's comments. Shiawassee Flats National Wildlife Refuge has large forested areas where there just is not any understory remaining. Kensington MetroPark had a similar problem which was controlled by expert marksman culling at night. Let keep some balance in our thinking and appreciate the virtues of unskewed biodiversity in our parks.
Thu, 01/14/2016 - 10:14am
I applaud Ann Arbor. More communities need to address this problem.
Thu, 01/14/2016 - 10:38am
Leave the deer to multiply and grow in population as much as the deer like. If the people against the cull complain, let them fund the even bigger cull. They don't understand the ecology.
C.O. Austin
Mon, 01/18/2016 - 8:17am
This is one "ecologist" giving an opinion and it sounds like a PR piece. Did city council hire a PR writer? This one ecologist lending his name to a PR piece, not "ecologists" as the misleading title suggests.
Michael Green
Thu, 01/14/2016 - 10:40am
I totally believe in weeding out the deer heard in areas where the are causing problems. BUT I don't believe that they should pay snipers to do this when we have a thriving youth population wanting to hunt. Why not have the youth hunt in these parks make the child by a park tag and be accompanied with a parent and someone from park services to ensure that the child indeed kills that animal. The state makes money off of tags and the deer heard get handles in a way it should. Closer to towns or population would be archery only and further from populated areas could possibly be firearm. Problem solved and maybe we can fill a pothole with the tag money. If anybody wants to contact me about this matter and possibly put it into effect feel free @ www.sportsmansquest.com/facebook
Fri, 01/15/2016 - 7:27am
Archery culls are performed in several towns but it's usually by vetted expert archers, many of them police officers, not kids, and it takes less archers than you might think. Recent example in Mt. Lebanon, PA. Another in Trumansburg, N.Y. They don't even need to close the parks. Recent changes in MI law means that there would be no 450-foot rule. Search about deer culling in those towns for their detailed methods.
Thu, 01/14/2016 - 11:12am
A well written article to which I totally agree. Controlling deer through the use of repellents might work in your yard or garden, but is highly impractical for use on a large scale. Every time it rains the repellent must be re-applied. I would also prefer that professional hunters be used and the meat be processed and given to non profits that feed the poor and homeless. Of course we could release cougars into Ann Arbor parks since each one kills about 50 deer each year. We should however be reminded that with cougars in our midst we humans would occasionally become prey as well. I don't think that is a risk we are willing to take.
Thu, 01/21/2016 - 9:30pm
I like the idea of introducing cougars. It would not only help cull the too large deer herd, but, also, the human over population problem.
Thu, 01/14/2016 - 11:17am
Don't wait for Lyme disease to appear before you cull the herd. Opponents of the cull have NO IDEA how bad the tick situation could become, and how nasty Lyme disease is. Here in New England you need to do a full body tick check after every outdoor activity. And your kids and pets too! Ticks also carry some other very nasty pathogens, some of which can be fatal. A whole new industry has sprung up to spray people's yards for ticks. Pollinators, anyone? ....not with all this spraying!! My neighbor has his yard sprayed 5 times a summer and butterflies have all but disappeared around here. It's so sad. And please, don't believe the story of " the rotten egg solution will stop them". I'm a gardener and the egg mixture is temporary at BEST. As deer populations creep higher and deer get hungrier, they will eat anything. For example - Soap to repel deer? A visiting scientist friend of mine could not sleep one night and went for a walk in the orchard. He observed deer eating the soap attached to the trees.
Thu, 01/14/2016 - 12:10pm
The deer density in Ann Arbor is below the level that many studies recommend as optimal for forest regeneration, read the research at http://www.deerfriendly.com/deer-density-and-forest-regener… This article compares the current U.S. population to 100 years ago when deer were nearly hunted to extinction. The total U.S. deer population has been declining since about the year 2000 and is currently below its estimated presettlement population, see: http://www.deerfriendly.com/decline-of-deer-populations Contraceptive methods have successfully been used to control deer and other free ranging animal populations, several communities are currently experimenting with these approaches in order to advance the science, see: http://www.deerfriendly.com/deer-population-control
Christopher Dick
Thu, 01/14/2016 - 3:17pm
Dear Kent, just a couple of points relevant to your comment. First, deer densities are very heterogeneous in Ann Arbor. There are some parks where deer are far above thresholds for forest regeneration. And there are some areas that may show relatively little damage. In the Birds Hill study, the researchers measured saplings in an oak forest and found no oak saplings - but lots of damaged cherry and white ash. Because of emerald ash borer, the white ash are not likely to mature. Second, I am not comparing deer numbers to densities 100 years ago when there were no deer in S Michigan. They are higher now (averaged over several years) than they were 20 years ago or even 150 years ago. Part of this is the result of the favorable habitat created through urban sprawl. It is not applicable to take recommended deer herd densities for open forest or rural areas and apply them to urban landscapes.
Thu, 01/14/2016 - 5:06pm
Can we also have a politician cull? They have far exceeded their carrying capacity. Deer are much more likable...CUTE, SMART, NON CORRUPT, GRATEFUL, ETC
John S.
Thu, 01/14/2016 - 10:39pm
Why won't some people listen to the advice of professional biologists who know far more than they do about the nature of the problem and the best approach for dealing with it? I'd guess they are squeamish Bambi lovers who have never hunted, killed, skinned, and eaten an animal during their lives. There are deer in my back yard nearly every night. They eat the neighbor's arborvitae. It's not pleasant picking up all their scat. Culling is the best way of controlling their populations.
Fri, 01/15/2016 - 3:11am
As a park steward who spends 150+ hours in a local park working in forest restoration efforts I can confirm the professors comments. The deer are overgrazing, eating the vast majority of new plants and buds. There are no small trees and very few native smaller plants that survive. They also do extensive damage to many mature trees by rubbing their antlers against the bark. These forests did not evolve to support this many deer.
Nancy Stoll
Fri, 01/15/2016 - 11:41am
Thank you Chris for your article. I have worked in Ann Arbor's natural areas and my own wooded back yard for many years and the deer population is definitely overabundant with resulting damage to the many wild plants that support so many other creatures. We need a balance, not deer parks. I wish the anti-cull folks would have compassion for baby birds and wild flowers.
Fri, 01/29/2016 - 3:18pm
:-) You tell it, Nancy!
Mark O'Brien
Fri, 01/15/2016 - 12:04pm
About the only effective method of keeping deer out of your garden is a 15 ft high deer fence. Over the years I have seen the latest "fad" of deer repellents, from bars of Irish Spring soap, coyote urine, capsicum, etc., and while there may be some initial repellent effect, it soon fades. We have had a herd of up to 7 deer near our backyard, all most likely from County Farm Park. Deer become habituated to the urban setting, and have no problem bedding down just beyond our fence. For those against the cull, I see it mostly as aversion to having an animal killed, no matter what sound science is behind the argument for culling. Yes, white-tailed deer are beautiful animals, and I enjoy seeing them in nature. However, our suburban/urban environment has become attractive for all the reasons previously given, and without a cull, we are setting our community up for a series of ecological and monetary problems.
Fri, 01/15/2016 - 12:31pm
Thank you Chris for your well reasoned position with ample evidence to back it up. I am also perplexed by the argument that culling the deer herd with expert sharpshooters is less humane than killing them through collisions with cars. Every time I see a dead deer on the side of a street or roadway, I am reminded of hazards the overpopulation of deer (relative to the habitat available) presents and inhumane injuries and deaths they suffer.
C.O. Austin
Tue, 01/19/2016 - 2:48pm
Maybe we should shoot teen texters and drunk drivers as well. Every time I see a body under a sheet by the side of the road, I'm reminded of how inhumane their deaths are.
Fri, 01/15/2016 - 1:29pm
Dr Dick You write: "Ann Arbor’s high deer abundance is part of a much broader phenomenon. In the past 100 years whitetail deer numbers have swelled to historic highs across their range. Deer overabundance poses a threat to many North American ecosystems." Why is a maple tree more valuable than a deer? Who are we to make that judgement? Why is one equilibrium better than another and who made us the policemen of nature in the first place? What is the broader issue you are alluding to in the quote above? Can it be the killing of the natural predators of deer by humans so that the sport of hunting can be more profitable? Why not address the real problem instead of the consequence? Why are YOU not addressing that issue as a scientist? We as a society have a very bad track record in fixing things in nature at least the past 200 years. Is this another attempt of us fixing what we actually destroyed in the first place? Why is it going to work this time?
C.O. Austin
Mon, 01/18/2016 - 12:00am
All excellent questions. part of the reason city council gives for the cull is not to support one species over another, yet by killing deer, that is exactly what they are doing...Selectively deciding against one species. The logic of "Let's kill deer so we can plant plants that attract deer" is ludicrous.
Fri, 01/29/2016 - 3:34pm
With all due respect, it's rather about protecting the Human Species above all other; nothing else is ultimately as important. Prof. Dick is correct regarding the eventuality & inevitability of disease that this out of control deer herd issue poses to our Ann Arbor residents. And once it begins, it will proliferate so quickly that the remedy will be too late to save many from the dire consequences of these debilitating diseases. Should it be allowed to get to that level, the remedy will also be a complete removal of the deer population within the City and outlying environs, which prudent management now will most likely prevent. No one wants to see Bambi killed. This is a difficult and heartfelt decision that needed to be taken to protect our citizens, our families and loved ones from the dire eventuality if the deer cull were not instituted. Not only by disease, but through motor vehicle accidents, which not only kill and inhumanely injure and maim the deer, but result in the same to humans. No one is taking this decision lightly, or feels good about it, but it is necessary and the responsible decision to make to protect our Human Species first, above all.
Sat, 01/16/2016 - 8:53pm
Deer have flooded into cities, plenty of food and no hunting, other than preditory autos, the density is often greater than it is out in the country. My own city's council grabbed their ankles at the first whinning anti hunter, even with many areas that hunting (archery) in some kind is appropriate. Now dead deer on the road and wiped out gardens and parks. Face it, anti- hunting/ animal rights is a relgion, they're wecome to it but don't them force it on everyone else.
D Thomas
Sun, 01/17/2016 - 10:19am
If the science is accurate and the problem is real, I support a cull. There is no easy way to keep them out of the city. However, there is one point that has not been made. Beyond the fact that deer are "eating your gardens" and becoming road kill is that too many people are feeding them. Lastly, why is the council paying for the cull? Can someone explain that? Why not allow more deer hunting permits in the region? I know people who would pay for an extra opportunity to hunt. Thus, the city/state makes money; not loses it, the hunters are happy; the gardeners are happy and there are less auto/deer collisions, so insurance companies are happy. This forum should lead to a more sensible plan should it arise again.
Sun, 01/17/2016 - 2:52pm
Have some of the commenters confused Homo Sapiens with Odocoileus Virginianus?
Mon, 01/18/2016 - 1:30pm
Those who have chosen to highlight the "species versus species" aspect (e.g."why is a maple tree more valuable than a deer?) merely pose a classical false-choice scenario, which unfortunately lends little to this debate. Focusing on the tree or in fact all of the vegetation can still cause one to lose sight of the forest. A forest is a complex ecological community of many organisms. Thus it's not just wildflowers and tree progeny that are damaged by high deer numbers but also native butterflies, bees, small mammals, amphibians, and certain birds, something that Professor Dick was careful to point out. It's impossible to be a purist in the urban environment, as the landscape level changes that occurred following settlement pretty much changed all the natural rules a long, long time ago. The only "fix" in sight is that of ongoing management to help contain a species that causes a disproportionate degree of ecological mayhem.
Linda Fliehman
Wed, 01/20/2016 - 2:42pm
The comment regarding Lyme disease was spot on. Last week, I lost a dear friend to Lyme. I challenge those who scoff at the notion deer don't pose a problem roaming through yards and causing dangerous collisions. Don't discount the viciousness of Lyme Disease, I've seen it first hand and believe me it's spread is easier than you think! Do your homework.
Sun, 01/31/2016 - 7:39pm
I applaud A2! Deer are beautiful creatures as well as destructive. Personally I don't mind seeing Bambis uncle and mom hanging from a pole - it means I can actually take care of myself that I have good food to eat, and that I am an active manager of the land. What is the problem with management? In the absence of management you see the population explode and then the deer starve en masses or cause increased accidents along with the destruction to the landscape. The naysayers need to get educated. See Don Wallers studies from Wisconsin. In the absence of management you become a spectator. Get out there people. Learn botany. Learn how to identify invasive species. Learn how to identify native species. Do some floristic quality assessments. Learn how to identify deer browse. And then go out and record over time your observations. I bet that instead of jumping to criticize the professionals explaining in basic terms you'd be on the same page. Education is key. If you're just against hunting well then good luck to you, and you don't matter anyways.
Sun, 02/21/2016 - 11:51am
What about condoms?
Thu, 04/21/2016 - 12:14pm
Christopher, Thank you for a rational presentation of the facts regarding urban deer management in Ann Arbor area. Frankly I'm more concerned about the opportunity to speak freely on matters of biology and related environmental matters. The messengers and the thoughts that run contrary to the 'herd' are often culled and eliminated themselves. Please continue to share your experience and knowledge, there is a community out there that does listen and can think for themselves. There is a also a community out here that emulates the 'queen of hearts' approach to all who disagree with their opinions (or self declared facts). You've enriched the forum.