Wednesday, December 10, 2014

Oh Deer

For some time now I have been working on an extensive and unsolicited report covering my thoughts on the management of Washtenaw County’s urban deer population.  That article is both long and unfinished. Because the City of Ann Arbor is hosting a meeting on deer management options tonight at Huron High School, I am sharing with you an abridged version of the report. Think of it as an executive summary. My key conclusions are as follows:

  1. Deer in urban and suburban areas can reach higher densities than they would in rural and other more “natural” areas. This is due to ample food sources in urban areas (backyards, natural areas and parks) and overall reduction in mortality rates. The reduction in overall mortality is due to a loss of human hunting pressure and reduced risk of automobile collisions. From a historic perspective, the loss of large predators (wolves and mountain lions) has contributed to an overall increase in deer populations across the region. The lack of predation pressure is unlikely to be a major cause the increase in deer density in urban areas of the county compared to rural ones. A 2005 study conducted in Jackson and Washtenaw Counties found that urban deer fawns experienced a higher rate of mortality from coyotes than those in rural areas.
  2. The heterogeneous and patchy nature of urban areas as they relate to deer habitat mean that deer tend to clump in particular areas in cities: parks, riparian corridors, and residential areas adjacent to large wooded areas. This means that in some areas of the city, residents are far more likely to encounter deer in their neighborhoods. In other neighborhoods, there may be no deer.
  3. Before we (The City, The County) undertake any deer management plans we need to know three things: a) The approximate size of the deer population; b) how the density of the deer population varies within the city; c) the approximate amount of damage the deer are causing. If we don’t have a baseline population estimation for the overall number of deer and the number of deer in specific areas of the city, we will not be able to evaluate the success of any management program. Also, in order to design an effective management program we will need to know what the largest sources of deer damage are in the city. Broadly speaking, I think we will need to know the costs of three types of deer damage: the approximate annual cost of deer-vehicle collisions; the cost to private gardens; and the cost to city natural areas. Estimating the cost of deer damage will allow us to evaluate the cost-effectiveness of the program.
  4. The rate of deer-vehicle collisions has been increasing slightly since 2008 (Ann Arbor Chronicle. These collisions appear to be concentrated on a few specific roads.  Because of this, the risk of deer vehicle collisions could likely be reduced successfully by removing vegetation at roadsides and improving lighting along high-risk roads.
  5. The city has taken some heatfor three questions on theironline survey that begin with "Research concludes that lethal removal measures are most effective for managing a deer population," Based on my reading of the peer-reviewed research, this statement is true. Perhaps it is a leading statement. Nevertheless, due to the biology of white-tailed deer the most effective way to reduce their population density within an area is lethal removal. This does not mean though that we have to do anything about the deer population in the city. I think that after quantifying the city’s deer population and the damage it is causing, an option on the table should be to do nothing further.
  6. If we want to reduce deer populations in the city, we need to commit to the program for the long term. Deer reproduce very quickly. A female can reach reproductive maturity during her first year and can give birth to between 1 and 3 fawns each year. A one-off approach or even an program that just lasts a few years will at best yield temporary results.
  7. Killing deer is the most effective way to reduce deer populations. Increasing annual mortality of reproductive age females will both reduce population growth and deer density. We can’t introduce wolves or mountain lions in an effectively--the wolves would likely leave the city and human-mountain lion interactions can be problematic. There are lots of coyotes in the city and they have difficulty bringing down a mature doe. Other options have been proposed and they are also not good:
    1. Sedating and moving deer. This is expensive ($1000/deer) and ineffective in a number of ways. Other deer will fill the space left by the removed deer and relocating deer is so stressful for the animals that they suffer 80-90% mortality within a year.
    2. Sedating and euthanizing deer. This is expensive (the exact cost per deer escapes me) and could render meat unusable.
    3. Contraceptives. This is currently illegal under state law. It is also expensive ($1000/deer). It has been effective for deer in closed populations. The deer in the greater Ypsi-Arbor area are not a closed population.
  8. There are three ways that cities generally enact lethal deer control policies: hiring certified sharpshooters, having police cull deer and a managed special hunts. Depending on the number of deer targeted, the costs of these programs range from $100 to $250 per deer. Programs using outside sharpshooters are often ineffective in the long term as they tend to attract the most protest from residents. Deer reduction strategies that use police or city managed hunts tend to be more effective for long term control.
  9. If, after evaluating the size of and damage caused by Ann Arbor’s urban deer, we decide to undertake a reduction of the deer population, I think the best option would be a city managed archery hunt. This would involve:
    1. Changing the city’s ordinance forbidding bow shooting in city limits.
    2. Creation of a committee to oversee the deer hunt.
    3. Creating special rules for the hunt and criteria for evaluating hunters who apply to hunt in the city.
    4. Hunters applying for permission to hunt in the city.
    5. The committee evaluating hunters (experience bowhunting, ability to commit time to the hunt, accuracy with a bow, criminal record/history of poaching).
    6. An annual hunt during the regular archery season (October 1 - December 31).
    7. Annual evaluation of the success of the hunt and adaptation of the management plan.
  10. I think a managed bowhunt is the best option for lethal control of deer because:
    1. The costs of administering the program can be offset by application and licensing fees of the hunters.
    2. It has the potential to be a long term program.
    3. Archery hunting is safer than firearm hunting. There were only two archery hunting accidents in Michigan last year. One involved the hunter falling out of a stand while asleep. In the other, a hunter was walking with an arrow nocked and slipped stabbing himself in the leg. Neither was fatal.
    4. Archery hunting is less disturbing to adjacent residents than firearm hunting. Beyond the acoustical differences between bows and guns, the range of a bows are very short ranged. In an urban archery hunting program in Pennsylvania, the mean distance of shots taken was just 20 yards.
    5. Managed special archery hunts are successfully employed by a number of other agencies in Southeast Michigan (Source).

The decision to manage our urban deer population is complex and involves ecology, public policy and ethics. Growing up near the intersection of Miller and Newport, we only saw one deer in our yard in the 1990s. Recently, I have seen deer walking down my parents’ street and numerous deer in Miller Woods. Seeing wildlife in the city is wonderful. I know it brings others as much joy as it brings me. Managing deer is more difficult than managing our other urban critters. Due to their size and their status as a protected game species, one cannot simply trap and relocate a problem deer as one would with a bothersome groundhog or raccoon. I am glad to see the city is thoroughly evaluating its options and engaging with citizens before making its decision.

Additionally, the topic of killing deer is an emotionally charged one. As a community I think it is important that we respect the strong emotions that our fellow citizens bring to this discussion. It is too easy to paint hunters as bloodthirsty or callused hicks and those opposed to hunting as unrealistic over soft animal-lovers and tree huggers. Regardless of where we stand on the topic of urban deer control, I think it's important to strive to understand why those of use on opposite sides of the debate feel the way they do.

So there you have it gentle reader, my thoughts on managing Ann Arbor's deer heard. In a nutshell, we should figure out how many deer there are, where the deer are and how much damage they are causing. Using that information we should then decide if we want to do anything. If we do something, physical improvements can help reduce deer-vehicle collisions. If we opt to reduce populations, we should employ a managed special archery season in the city.

I'm curious to hear your thoughts and questions. Please share them in the comments. You can also share your thoughts tonight at 7 pm at Huron High School or using this online survey.

Further reading:

Bissell, K. (2014). Deer Management/Status Overview Southeast Management Region 081 Deer Management Unit. Michigan Department of Natural Resources.


Hiller, T. L., Campa III, H., Winterstein, S. R., & Rudolph, B. A. (2008). Survival and space use of fawn white-tailed deer in southern Michigan. The American Midland Naturalist, 159(2), 403-412. (pay-walled)

Leary, M. A. (2012). Our Deer: Living amid a population explosion. Ann Arbor Observer.

Michigan Department of Natural Resources (2006). WORKSHEET FOR ESTABLISHING DEER POPULATION GOALS – DMU 081, 2006- 2010.

Washtenaw County (2014). Status Report: Deer Population Trends and Impacts in County Parks.

Wildlife Society Bulletin--Special Issue: Ecology and management of deer in developed landscapes, Sept. 2011 (pay-walled, mostly)


  1. A wonderful, thoughtful essay. I'm going to spread it around.

  2. Well thought out.
    Some details:
    Relocating deer can spread disease and is illegal in MI.

    >Other deer will fill the space left by the removed deer
    "Analyses show that a population expands slowly as a series overlapping home ranges because female offspring remain near their dams for life."
    The easy reading version: