Deer and the Population Problem

Posted August 4, 2015 by varmentrout
Categories: Sustainability

We have been posting about Ann Arbor’s deer herd and the issues it raises since last December (see our summary page, What Do We Do About the Deer? for a list of posts and also useful resources and links to news articles).  There are many reasons to be concerned about the size of the herd.

Deer-Vehicle crashes.  According to SEMCOG, there were 952 reported deer-vehicle crashes in Washtenaw County for 2014 (33 injuries), and 51 (1 injury) in Ann Arbor.  Anecdotally, there are many more “near misses” where drivers avoid a crash but not an adrenaline rush. (The numbers reflect only reports made to the police.)

Lyme Disease.  (Be afraid.  Be very afraid.) The presence of Lyme disease in humans and the prevalence of deer are closely correlated.  Lyme is a truly scary disease that is curable by antibiotics if caught in the early stages of infection.  Often, however, the disease is not detected early and may even be mistaken for other diseases.  In its chronic form, it has long-lasting neurological effects.   This is not just another little “bug” that most people get over easily.  It can be life-changing.

The migration east of Lyme Disease. Note that Jackson County is now shown as potential though unconfirmed.

The migration east of Lyme Disease. Note that Jackson County is now shown as potential though unconfirmed.

Lyme disease has affected some individuals in Washtenaw County but there are no verified cases of transmission here as yet.  In order to verify transmission, the tick itself must be sent to a laboratory and tested for the presence of the bacterium.  It is assumed that all current cases in the county originated from an infection elsewhere.  However, according to the State of Michigan, Lyme disease is an “emerging disease” and is steadily moving eastward from southwestern Michigan, where it was first described in our state.  How is it moving? Deer (they don’t recognize county boundary lines).

Shamefully, individuals who oppose lethal culling in Ann Arbor have made the technically accurate but misleading statement that “deer don’t carry Lyme Disease”. Lyme is an infectious disease caused by bacteria that are carried by deer ticks (black-legged ticks).  It has a complicated disease cycle.  Young ticks (nymphs) exist primarily on rodents, especially the white-footed mouse.  The mouse is the reservoir host for the Lyme disease bacterium and does not appear to be harmed by the infection or the tick burden.  The ticks climb onto deer as adults for their blood meal prior to reproduction.  Deer carry them into human contact.  Without deer in the neighborhood, Lyme Disease transmission would occur very rarely.  There is general agreement that Lyme disease incidence and deer density are strongly correlated.  In one important study, a severe reduction in deer density reduced the number of cases in a Connecticut community markedly.  The deer population was reduced by over 80% by a hunting program, to about 5 deer per square kilometer (just over 12 per square mile).  The incidence of Lyme Disease was reduced by 80%.

“Reducing deer populations to levels that reduce the potential for ticks to successfully breed should be an important component of any long-term strategy seeking to reduce the risk of people contracting Lyme disease,” they concluded. “Additionally, good hunter access to deer habitat and a wide variety of management tools (bait, unlimited tags, incentive programs) are important components of a successful deer reduction strategy.”

This video has good pointers on how the presence of Lyme-bearing ticks can modify the way you can enjoy the out-of-doors.  It is also a good review of Lyme disease, the deer-tick-mouse equation, how to deal with ticks that you bring home, and other good information.  Really, it is worth your time. Beautifully produced with views of Nantucket.

Our Natural Areas. Ann Arbor has invested a great deal of money both to acquire our natural areas and parks and to maintain them.  We have hundreds of volunteers who turn out to remove invasive shrubs and do other maintenance tasks.  One reason for this is that many of us appreciate the natural world, including not only the flowers and trees but the birds, insects, small mammals and the sometimes miracle of frogs, toads and salamanders.  In preserving the natural areas, we are creating a living collection of life.  As our previous posts Deer and the Web of Life and Deer and the Flowers of Earth have expressed,  burgeoning deer populations are a threat to the entire ecosystem.  This has been shown in study after study nationally, and we have some local studies too.  Deer are explosively fecund and their population increases geometrically, as we explained in Deer and the Numbers Explosion. They don’t give the rest of the living world much of a chance.

A swallowtail butterfly caterpillar in an Ann Arbor backyard

A swallowtail butterfly caterpillar in an Ann Arbor backyard

Our Gardens. People who are not gardeners or who do not maintain a landscape are often dismissive of those who care about plants in their own backyards.  It is hard to express the anguish of losing a cherished plant to those who simply don’t regard this as important.  And the thousands of dollars lost in landscape damage is dismissed by commenters as “rich people worried about their…”  Yet these are heartfelt losses.  And I would also plead that our backyard flowers support a lot of wildlife, beginning with insects (pollinators are in vogue just now; even President Obama is on their side) and birds who love the nectar, the seeds, and the insects that garden flowers provide.

This squash plant has been stripped of all flowers, fruits and growing tips

This squash plant has been stripped of all flowers, fruits and growing tips

DCF 1.0

A previously productive vegetable garden that once fed a family has been occupied by a deer herd

Even more basic is the human need to be able to raise vegetables from one’s own soil (or in a public garden).  The Ann Arbor deer are now affecting community gardens maintained by Project Grow and have caused what I will term as tragic losses to home vegetable gardeners in some locations.  I myself have had to surrender my vegetable garden, though it was of great importance to me.  (My garden blog was almost all about vegetables.)  The pictures shown here were of an extensive vegetable garden on the east side of Ann Arbor that is now in ruins, an occupied territory.  The unsympathetic who suggest “planting resistant plants” haven’t considered that we have selected food plants over millennia to be highly edible, and the deer are happy to participate. When deer attack them, they eat the tender growing parts, the buds, young leaves, developing fruits. They devastate the crop.

Basic safety. In addition to all these problems, it should be noted that these are large animals with sharp hooves, and, in the case of bucks, antlers.  It is not possible to confront them in person.  There are stories which I will not attempt to document here of attacks on pet dogs, intrusions on decks, and other threats to personal territory.

So what are we to do?  It is clear that we need to limit (reduce) the deer population in Ann Arbor.  They are beginning to penetrate even to neighborhoods where they have not been seen until recently.  But they are virtually an occupying force in some areas.  The City Council and Administration have recognized that something must be done.  After a nearly year-long process including much public participation, a staff report recommended a management program which included a lethal cull to be conducted under very restricted conditions.  (NOT hunters in your backyard.)  There was pushback.  A special work session was called in which the Humane Society of the US was given an opportunity to present information about the “nonlethal” approach of using experimental contraception and/or surgical sterilization instead.  The presentation is here.  Now it has been announced that the City Council will consider a resolution on August 17, 2015.  The method of limitation of the deer population that will be proposed has not been announced.  There will also be a public hearing at that meeting.  Any Ann Arbor resident may speak on this topic without signing up ahead of time.  The actual text of the legislation will by that time be available on Legistar.  (Go to 8/17/2015 and click on Meeting Details to find the text.)

Soon we will know what our City will do to address this real and present problem of excess deer population in Ann Arbor.

ADDENDUM: One of the best examples of a deer management plan in our area is that practised by the Huron-Clinton Metroparks.  This organization manages many significant open spaces throughout SE Michigan.  They long ago recognized the importance of deer to their overall management of these areas.  Here is their latest Huron Clinton Deer Plan (July 2015).

Deer and the Flowers of the Earth

Posted May 31, 2015 by varmentrout
Categories: Sustainability

Hepatica acutiloba (photo by R.W. Smith) Spring, beech-maple forests.

Hepatica acutiloba (photo by R.W. Smith) Spring, beech-maple forests.

The land speaks in flowers.    

— Shawn Severance

Wildflowers are a major source of delight in a stroll through natural areas.  Indeed, a reason many of us choose to “take a stroll in the woods” is that a season of flowers has arrived.

Jeffersonia diphylla (Twinleaf). Early spring, rich forest. Photo by C. Peirce.

Jeffersonia diphylla (Twinleaf). Early spring, rich forest. Photo by C. Peirce.

But flowers have a much more important role in nature than to provide us a momentary pleasure. The beauty and scents are part of a pollination strategy for seed production.  Some flowers are pollinated by visiting butterflies, some by bees, and some by flies.  Night-blooming flowers are pollinated by moths. Tubular red flowers are often pollinated by hummingbirds.  All this flower sex makes for an important source of food for the pollinators.

Mitella diphylla (Bishop's Cap), spring, rich forest. Photo by C. Peirce.

Mitella diphylla (Bishop’s Cap), spring, rich forest. Photo by C. Peirce.

Trillium flexipes (Drooping Trillium) Spring, rich forest. Photo by Ann Arbor Natural Preservation

Yes, we are talking again about the food web, or as we have called it, the web of life.  Not only do the flowers feed their pollinators, but the fruits and seeds that the flowers produce are often important food sources for small mammals and birds.  The insects fed by flowers in turn are important in the diet of frogs and toads, snakes, and birds. The amphibians, birds and small mammals are the prey for raptors (birds) and sometimes larger mammals.  But it begins with the flowers.

The Impact of Deer on the Natural Landscape

Campanula americana, photo by Ann Arbor Natural Preservation.  Summer, openings in deciduous forest.

Campanula americana, photo by Ann Arbor Natural Preservation. Summer, openings in deciduous forest.

Lysimachia terrestris (Swamp-candles), photo by R.W. Smith. Mid-summer, marshes and fens.

Lysimachia terrestris (Swamp-candles), photo by R.W. Smith. Mid-summer, marshes and fens.

Those of us who love the natural world often see a wild place as a whole – the trees, the smaller plants, the small and larger mammals, the birds, the insects.  The concept of the ecosystem is fundamental to ecology; all the parts fit together, including the inanimate physical setting.  The food web is an integral part of that ecosystem and helps define the relationships within it.  But because the white-tailed deer is increasing out of bounds and is consuming a far greater proportion of the food resources in local ecosystems, they cause a degradation of the whole, making it less supportive of all the other living beings in it, and ultimately of the deer themselves (the carrying capacity is exceeded).

Aster laevis (Smooth Aster) fall, dry wood edges, prairies. Photo by B.S. Walters.

Aster laevis (Smooth Aster) fall, dry wood edges, prairies. Photo by B.S. Walters.

The problem is that deer have very demanding nutritional requirements.  They need approximately seven pounds of high-quality food a day (amounts will vary according to life cycle state).  As this study from the University of Missouri extension explains,  the diet needs to be relatively high in protein (15-20%), especially during antler formation and lactation.  They don’t get by on nibbling leaves or grazing on grass.   They eat tender buds and rapidly growing tips of plants, because that is where the protein is.  Their browsing can take out whole stands of saplings and young herbaceous plants (called forbs). One of the general effects of deer overbrowsing is the loss of both the numbers of plant species (diversity) and of the numbers of the plants themselves.  It is said that the quality of the plant community has declined. As shown in this long-term study from Wisconsin (overview) (scholarly paper) an area browsed by deer is likely to contain mostly ferns (not eaten by deer), grasses and sedges, and some non-native or invasive plants.   Even the species of plants that did seem able to co-exist with the deer were shorter and smaller. Tree regeneration was severely limited (seedlings did not survive).

Carex prasina (Drooping sedge), photo by A. A. Reznicek. Spring, wet deciduous woods.

Carex prasina (Drooping sedge), photo by A. A. Reznicek. Spring, wet deciduous woods. (Wind pollinated)

An alarming observation that the Wisconsin researchers made was to point out that many or most of the surviving plants employ “abiotic” pollination. This is usually wind-pollinated (grasses and sedges are wind-pollinated, as are trees, and ferns produce windborne spores).  They speculated that this could be because of loss of the animal pollinators “by altering the abundance and quality of plant food resources and habitat available to pollinators and songbirds”.  A circular causation here – if a plant species becomes too sparse, it may be difficult for pollen from another plant to reach it, especially if the pollinator is not present, partly because there weren’t enough flowers to feed the pollinator, so its population would decline…   But note that the nutritional value of the surviving vegetation to deer is also limited.

The language of flowers

So in conclusion, the absence of flowers is both an early indication of deer overabundance and an injury to the ecosystem resulting from it.  Aldo Leopold had a strong empathy for ecosystems and nearly personalized them in his concept of “the land”.  As we reviewed earlier,  he spoke of an ethic in which the land (the whole community of living things) was to be loved and respected.  If we view the entire community as an entity to be preserved, we should note this symptom (of lost flowers) with concern.  Washtenaw County Parks naturalist Shawn Severance, who has been involved for some years with studying the natural plant communities of Washtenaw County parks and natural areas, said it this way:  “The land speaks in flowers.”    Yes, and it is trying to tell us something.

Photographs of flowers are by permission of the photographers and of  University Michigan Herbarium.  They should not be copied without permission (ask at info@michiganflora.net).   All species shown here were found at Ann Arbor’s Bird Hills Nature Area at some time in the past and have a high conservation coefficient (are considered high-value species).

Deer and the Web of Life

Posted March 26, 2015 by varmentrout
Categories: Sustainability

“I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer.” – Aldo Leopold, A Sand County Almanac.

As we said at the very beginning, much of the controversy surrounding the solution to Ann Arbor’s deer problem is based on values.  One set of values that is crucial to this question is how one views the importance of the natural world, and how one judges its components.  There are some major philosophical and functional questions here, and often they are not examined so much as taken for granted.

Does “nature” have an inherent value, or is it only valuable in economic terms and its usefulness to humans?

Is there a moral basis for preserving wilderness, or is it to be judged solely on recreational use and conservation of certain resources (lumber) for future exploitation?

Are some species more worthy than others?  Or is every species deserving of protection?

These questions first emerged in America toward the end of the 19th century, as the expansion of civilization across the continent was drawing to its finish. President Grant signed some of the first legislation establishing Yellowstone National Park.  (The second national park was Mackinac National Park in Michigan.) John Muir, who died in 1914, was a major leader in the preservation of wilderness and conservation of wild species and the founder of the Sierra Club.  He was influential in Theodore Roosevelt’s moves to strengthen and expand National Parks.  He saw natural areas as having a transcendent value, a source of spiritual inspiration, rather than as treasures to be exploited. The questions are still relevant today, as every fight between mining operations, lumber interests, developers or ranchers and conservationists demonstrates.  (Note the recent battle over the fate of wolves in Michigan.) Aldo Leopold, who was most active during the first half of the 20th Century, furthered the discussion with his early work on ecology.  We quoted his careful work on “deer irruptions” previously.  Leopold brought some rigor and analysis to the understanding of how wild systems work, but he also enunciated a philosophical position which he called the “land ethic”.  He had a strong empathy for all parts of the natural system, beginning with the soil and incorporating the plants and the animals.  In the foreword to his landmark book, A Sand County Almanac, (1949) he says,

“That land is a community is the basic concept of ecology, but that land is to be loved and respected is an extension of ethics.”

Unfortunately (from my perspective), that is an ethic that is not universally shared.  Even many supporters of maintaining biological diversity often justify it on an utilitarian basis, e.g. “there might be a new antibiotic or a cure for cancer there”.  For Leopold, and for me, every part of the natural community (what he calls the “land”) is of value in itself. There is an aesthetic but also a reverence for all these members of the natural community and the beautiful fabric that they weave.

Favored Species

But of course any of us do discriminate among species.  When I was a child, I couldn’t figure out why God created the mosquito or the rattlesnake.  Now I ruthlessly weed out “invasive” plants (usually plants that are not native to our area and are weedy in behavior, crowding out other plants).  I certainly favor songbirds over starlings (another invasive).  But if we care about the natural world, we recognize that most species, especially those native to the community, have a place in the “web of life”, where there are many dependencies.  Even the less glamorous deserve some measure of respect. What has been distressing in the current discussion about deer is that some people evidently do place the welfare of individual deer above that of all the rest of the natural world.  In the A2 Open City Hall survey (we summarized it here) the question was asked,

In general, do you believe deer are a more valued species than other urban mammals (coyote, rabbit, squirrel, skunk, woodchuck, etc.)

to which 26% of respondents answered “Yes”.  The question does not ask about birds, plants, reptiles or amphibians, much less invertebrates like insects.

A Question of Balance

A simplified food web illustration. Arrows point to the one who eats.

A simplified food web illustration. Arrows point to the one who eats.

The notion of the “balance of nature”, in which the various members of a native community interact with each other to form a more or less stable condition, is based on the concept of the food web.  Plants form the basis of several food chains (combined in the web) in which energy is captured by photosynthesis and passed along from animal to animal, where prey animals are ultimately consumed by predators.  (Prey animals may be herbivores, omnivores or carnivores.)  Predator-prey relationships exist at each step (see our explanation), including between herbivores and plants.  This means that an excess of any predator can depress the ability of critical parts of the food web to supply the needs of the rest of the web. As we noted previously, without a predator (and you’ll notice the wildcat is missing in this web), deer will employ their tremendous reproductive capability to exceed the ability of the plants in their community to support them.  But the rest of the food web suffers, too.  This has been especially evident in the forests of North America.  A post originating from the august Nature Conservancy states,

In our opinion, no other threat to forested habitats (than the white-tailed deer) is greater at this point in timenot lack of fire, not habitat conversion, not climate change.

Think about it.  Most deer, even those in our luxury setting, are hungry all the time.  They need a high-quality diet.  Estimates of how much vary, but about seven pounds a day seems fairly conservative.  And they want it to be high in protein and low in toxic compounds.  They are not grazers of grass, but nibblers of buds and tender young foliage.  In fact, much of what they eat is what we would seek out if we had to live in the wild and had no animals to eat.  Buds, fruit, tender growth, nuts, acorns, even mushrooms.  They have also been observed to eat baby birds.  (Protein is hard to come by.)  They go through a habitat relentlessly, scooping up everything edible – by their standards. There are numerous studies of how deer have affected the Northern forests.  I like this one from Wisconsin.  It is based on rigorous studies using exclosures and plant assessment techniques. From the article:

Deer account for at least 40 percent of the change seen in the forests over the past half-century or so. “The study links microcosm to macrocosm. We have exclosures in the same region where we have documented long-term changes in the plant community over the past 50 years. These are giving us the same message.”

Some previously common plant species (trees and shrubs) have become so rare that they are no longer included in the assessment studies.

A Formidable Influence

Aldo Leopold killed a wolf early in his career and then regretted it.  In the fires of the eyes of the dying wolf, he saw a truth.  He realized that without the wolf, the mountain where it lived would suffer.

“I have watched the face of many a newly wolfless mountain…have seen every edible bush and seedling browsed…every edible tree defoliated to the height of a saddlehorn.  Such a mountain looks as if someone had given God a new set of pruning shears and forbidden Him all other exercise…I now suspect that just as a deer herd lives in fear of its wolves, so does a mountain live in mortal fear of its deer.”

Deer are extremely adaptive, have a high reproductive capability and an unending appetite.  They are a very old species on this continent.  In her recent book The Sixth Extinction, Elizabeth Kolbert relates how the introduction of humans to the North American continent finished off many large mammals (megafauna), including mammoths.   But “white-tailed deer have a relatively high reproductive rate and probably remained plentiful even as the number of mammoths dropped.”  This is referring to the likelihood that deer were able to supply meat to the new predator on the continent and yet survive and prosper.  Unfortunately, we are no longer filling our role as the top predator in the food web.  The balance of nature is off kilter.  I don’t think that we want to bring back the wolves in sufficient numbers to keep them in check. For the sake of the deer as well as all the other species dependent on the wilderness,  we need to fill our place in the natural order.

Note: Posts on this subject, together with other useful resources, are on our page What Do We Do About the Deer?.

UPDATE:  An important study of the effects of deer in an Ann Arbor natural area has now been released.   The study, White-tailed deer (Odocoileus virginianus) browse damage in Ann Arbor, Michigan Bird Hills Nature Area, Winter 2015,  is by ecologist (and specialist in deer/vegetation interactions) Jacqueline Courteau and her independent study student at the University of Michigan, Moriah Young; it is based on data collected in February through April 2015.  (The authors have released the study for use and quotation, but it is not yet published in a journal.)

The study finds significant damage in tree saplings and shrubs.

This survey of 142 tree saplings (less than 2 meters tall) and shrubs in Bird Hills Nature Area shows that 80% have been browsed by deer, and 51% have half or more branches browsed. This level of browsing could interfere with forest regeneration and diminish the flowers and fruit available for birds, butterflies, and bees.

The study uses direct, painstaking counts of deer browse on specific woody species.

Figure 2 of Courteau and Young, 2015.  Note the high numbers of individual trees and shrub browsed >50%.

Figure 2 of Courteau and Young, 2015. Note the high numbers of individual trees and shrub browsed >50%.

The discussion also makes an important point about deer population counts.  As it notes,

A small population of deer that browse repeatedly in a small area due to barriers (roads, fences, etc.) or because of the lack of predators may damage vegetation as much as a larger population that ranges more widely.

 There are numerous figures and tables with specifics about the sampling areas.

Deer and the Vacuum Effect Fable

Posted March 8, 2015 by varmentrout
Categories: Sustainability

The City of Ann Arbor conducted a visual deer count by helicopter fly-over on February 10, 2015.  There are a couple of methods for assessing deer populations.  According to one recent study, use of a helicopter for visual counts while there is snow on the ground is as accurate as infrared, another frequently used, but more expensive, method. The City chose a day with good light and a good snow cover.  As reported by the Ann Arbor News, all areas of the city other than downtown and “near hospitals” were surveyed. According to the News, a second fly-over was conducted in early March.

Aerial survey of deer in a Washtenaw County natural area, 2014. Photo by Shawn Severance, WC Parks.

Aerial survey of deer in a Washtenaw County natural area, 2014. Photo by Shawn Severance, WC Parks.

The point of the survey, of course, is to determine the number and also geographical distribution of deer in the city.  This will be part of the report to Council as now promised for late March. (No results have been reported as of this writing.)  One of the problems with this technique is that deer tend to clump or “yard” under trees and shrubs in cold weather.  However, an independent observer using a drone noted that many deer trails were readily visible.  (One image is posted in the comment section of the News article.)

Once we have some numerical information (ideally, this would pinpoint herd numbers in different areas of Ann Arbor), we’ll need to identify the method to reduce – or, euphemistically, “manage” the population.  Ann Arbor is coming late to this discussion.  Wildlife biologists and managers all over the U.S. have been studying this issue for at least 25 years.  A great deal has been learned from careful observation of deer population dynamics and behavior.  We reviewed a critical part of this question in our previous post about deer population growth.  Deer have tremendous reproductive and regenerative capability.  So a program intended to reduce their numbers and their impact on our local environment must take that into account.

Deer as Gas Molecules

As we acknowledged in our first post in this series, the suggestion that we might employ lethal methods (i.e., killing or “culling”) to reduce the local deer population is truly horrific to some members of our community.  The lead speaker for this viewpoint is Tanya Hilgendorf, the President and CEO of the Humane Society of Huron Valley.  She and others have included as part of the argument against a cull the notion that it is pointless and ineffectual because killing deer in one location will create what is often called a “vacuum effect” by which more deer will inevitably be pulled into the void created by killing the deer in one region.  The basic argument from those opposed to culling by lethal means is this:

Killing the deer will only result in bringing more deer into the city from adjoining areas.  Because it will be ineffectual, it is therefore pointless and needless cruelty.

If gas molecules are suddenly given access to a vacuum (by lifting the barrier), they will rush in and fill the space so that the density evens out.

If gas molecules are suddenly given access to a vacuum (by lifting the barrier), they will rush in and fill the space so that density evens out.

The “vacuum effect” is based on an assumption that deer behave as gas molecules do.  Supposedly, if a vacancy is created in one area, deer will somehow sense that and there will be a massive flow of deer into the opened-up area.  Soon we’ll be back to the same numbers as before.

Many studies have shown that deer don’t behave this way.  Instead, deer favor a home range.  They mostly migrate into new areas only because they have exhausted the food in their home range.  In other words, if they have exceeded the carrying capacity of their current range, they may migrate.  But this is not caused by a vacuum created by the removal of other deer.

Home Ranges

The key to understanding deer behavior is the concept of the home range.  There are tens or perhaps hundreds of studies examining how deer modify the size of the home range under certain circumstances, and what factors cause them to leave the home range.  A landmark paper from 1992,  The Rose Petal Theory: Implications for Localized
Deer Management
introduced the key model for home ranges of does. This was one of a long series of papers by  William F. Porter (now at MSU) and his students in which meticulous research (using radio collars and other increasing refined and sophisticated tracking mechanisms) has followed individual deer to map their behavior under different conditions.

The rose petal model, after Mathews and Porter, 1992. Circles are home ranges of individual does, about 1/4 mile in diameter.

The rose petal model, after Mathews and Porter, 1992. Circles are home ranges of individual does, about 1/4 mile in diameter.

The rose petal model proposed by Mathews and Porter states that deer are matrilineal in social organization; does stay close to their mothers.  The first circle is the home range of a doe (these home ranges are quite small, only about a quarter of a mile in diameter).  Her daughter establishes a home range that slightly overlaps hers. Subsequent generations continue to overlap the original doe’s home range in a pattern resembling rose petals.  This type of close association within a family structure is termed philopatry.

The significance of this behavior to management is that if the deer in a particular very localized area can be eliminated (or significantly reduced), that area will likely stay empty of deer for quite a while.  Over time, adjacent family groupings will begin to encroach on the area, but that will not be immediate.

Bucks have larger home ranges. And yes, does will move farther under certain circumstances, usually when the food available no longer supports the herd, in other words when they exceed the carrying capacity of the immediate area.  (We discussed this concept in the previous post about Deer and the Numbers Explosion.)  This movement to a new feeding ground is called dispersal.

Much of the literature on deer migration and deer management acknowledges the importance of home ranges and their use.  Wildlife biologists have used increasingly sophisticated measurement methods to determine how specific population management approaches (i.e., culling) affect home ranges and migration.  This 2001 study by Kilpatrick et al. is just one example.  They found that reducing deer densities actually reduced the size of home ranges, as deer did not forage as far (because vegetation became more available with lower deer densities).  Here is their conclusion:

Population reduction programs at our study area did not cause the resident deer population to expand home range size or shift into adjacent habitat. We believe that localized deer reduction programs can be effective tools to manage problem deer herds. Deer removal efforts initiated to reduce deer damage to vegetation, particularly in urban areas, may have an added effect of reducing foraging range of the remaining resident deer.

Presumably, a program of deer management for Ann Arbor can use similar pinpoint deer population reduction.  This will benefit our wild and cultivated areas, and even the health of the surviving deer themselves.  Even in our lush urban environment, some deer are beginning to show signs of food deprivation.

Deer browsing in a vegetable garden in Ann Arbor. Note the visible rib structure.

Deer browsing in a vegetable garden in Ann Arbor. Note the visible rib structure.

 

Note: An ongoing list of posts on this subject, together with some other resources, is on our page, What Do We Do About the Deer?

UPDATE: The City of Ann Arbor has now posted maps of its two fly-over deer counts.   Here is the February 10 and here is March 6.

flyover map

The Ann Arbor City flyover deer count from March 6, 2015

Many of us believe that this represents an undercount. Observations by residents reporting to the Washtenaw Citizens for Ecological Balance have indicated much more penetration by deer into the central section of Ward 5, for example. Here is that map. It is being updated through March 2015.  (Reports may be made via deerannarbor@gmail.com.)

 

Deer and the Numbers Explosion

Posted February 24, 2015 by varmentrout
Categories: Sustainability

deer

This is not from Ann Arbor and is not one of the photos in the story cited.

In the most recent article about Ann Arbor’s deer problem, the Ann Arbor News presented a number of photographs from an anonymous contributor of deer near her residence, apparently in a public natural area.  As Tanya Hilgendorf of the Humane Society of Huron Valley (who passed along the photos) said of the person who took the photos, “She has watched many families of deer grow over the years, has come to know their individual personalities and witness their bonds with each other.”  The photos show quite a number of fawns, two in some pictures.

Now, the little fawn with his spotted coat is probably one of the most beloved images in our culture.  Is it because we all saw the movie Bambi when we were between the ages of 6 and 10?  Perhaps it is the same sentimental rush that comes with seeing the juveniles of any mammalian species, whether it is kittens, puppies, or fawns.  But actually, if you care about the forests of the North American continent, or about our own natural areas and the other wild things that live there, or even about your own garden, this image should make you run to hide under the bed in terror.

It’s all in the numbers

It is possible to find deer management plans (intended to limit deer populations) described from most states in North America. The reason is that throughout the 20th century, deer (of several different species) have increased hugely in numbers.  This is because of their tremendous reproductive capacity.

Predator-prey population dynamics from Hoppensteadt. Scholarpedia

Predator-prey population dynamics from Hoppensteadt, Scholarpedia

Deer have evolved to be a prey species.  The dynamics of the predator-prey relationship are well understood.  As this treatise states, “Species compete, evolve and disperse simply for the purpose of seeking resources to sustain their struggle for their very existence. ” The figure shown here uses a fox and rabbit as examples, but numerous studies have shown that many biological interactions are based on the same mathematics.  Note the steep rise of the prey species (rapid reproduction).  As the predator population increases with this availability of food, the population of the prey drops precipitously.  After the corresponding drop in numbers of predators, the reproductive capacity of the prey once again kicks in to bring the population back up. The web of life consists of many such interactions in a dynamic balance. (Herbivory – the predation of plants by animals – has also been shown to follow this pattern.  When herbivores such as deer exhaust the vegetation available to them, this is known as “exceeding the carrying capacity” and also leads to a population collapse.)

Deer (in all this discussion, we are referencing the white-tail deer, though there are other species) have only one reproductive cycle per year.  A doe can have two fawns at one birth, though triplets have been reported.  Poorly fed does may have fewer.  The female fawn will bear in the succeeding year, but the first doe, her mother, is also bearing again.  This means that the population growth is not merely replacement, but additive.

A single doe and her offspring over 5 years.  Males are not shown.

A single doe and her female offspring over 5 years. Males are not shown.

The figure above shows that a single doe can produce a population of 32 females in 5 years.  (Multiply by 2 to include males – a total of 64 deer from one fertile doe!)  The solid line points to the maternal doe; dotted lines show the births from the new does in each generation.

Assumptions:

1.The does are well fed and can support the birth of two fawns yearly.

2. Each birth produces one male and one female.

3. There are no deaths.

Deer population model 300x420Here is the same model, shown graphically.  Again, note that this is does only. If males (bucks) are born at the same rate, the numbers will be doubled, but they do not change the rate of increase.  As shown, there are 32 does at 5 years.  By 10 years, if no change in the assumptions, 1,000!  At this point, the original doe and some of her daughters and grand-daughters may have died or stopped reproducing, but their contributions are no longer significant.

At this point, the predator-prey model would predict that the wolf population will now have increased to exploit this food supply.  Oh, oops.  No wolves.

Of course, it is unlikely that deer populations in most Michigan locations, even in the protected environs of Ann Arbor, quite fit those assumptions. Various estimates are given on the life span of deer.  A maximum lifespan has been reported to be 20 years, but estimates for most situations are for 6-10 years.  Averages are lower where hunting occurs, especially for bucks. Some number of deer are killed by vehicles, there is some winterkill, and there have been a couple of instances of disease that reduced herds.  In addition, there are coyotes who probably don’t take down mature deer but are known to take fawns. The Rochester Hills staffer who spoke at the Ann Arbor February 5 meeting said that coyotes were apparently affecting deer populations there, but offered no details.

Still, it is obvious that this terrific reproductive potential is a major factor in the impact of deer on our environment.

History of deer in North America

History of white-tailed deer in North America, from U. Missouri Extension publication

History of white-tailed deer in North America, from U. Missouri Extension publication

In the early part of the 20th century, there was a deer deficit.  Deer have historically been a key factor in the abundance that this continent had to offer both to its earlier inhabitants (North American Indians) and to European settlers.  As an account from Minnesota tells it, both the delicious meat (used in making jerky) and the skins were important in the early days, and survival by humans in wild territory was made possible by taking deer.  The history of deer populations in Michigan and reaction to them is similar to other locations.  Deer increased as logging made habitat more favorable for them.  (Deer do best in clearings where there are seedlings, young trees and “forbs”, or herbaceous plants.)  They became seen as an inexhaustible resource and were hunted for export to other states as well as for food locally. Legislation to prohibit market hunting was finally passed in 1895.  Hunting bag limits were imposed.  Nevertheless, the deer population was dangerously low – it was estimated that only 45,000 deer remained in Michigan in 1914.  Further hunting restrictions, including a “buck law” (only bucks could be taken), allowed the herds to recover. At the same time, settlement and agriculture had converted much of the landscape, and wolves were being exterminated over the North American continent.  After all, they were eating our deer.  The DNR also began to create habitat protection for deer.  By the 1940s, there were 1.5 million deer and some of them were starving.

Data from Hickie, 1937, as illustrated by Leopold, 1943.  George Reserve (UM)

Data from Hickie, 1937, as illustrated by Leopold, 1943. George Reserve (UM)

The tendency of deer to increase their numbers well beyond the carrying capacity of their environment is termed an “irruption”.  This early (1943) paper (large pdf) by Aldo Leopold, one of the fathers of environmental conservation, lays out the story.  A reserve owned by the University of Michigan was stocked with 4 does and 2 bucks. Within 6 years, there were 160 deer, and they had exceeded the food supply in a 1200 acre reserve. Overbrowsing was observed, so the herd was “shot down” to 75, and later to 50, deer.  Leopold declared that the herd was now in equilibrium with its range – and that it was being held at that level by additional shooting.  Note that the graph also shows a  hypothetical loss of carrying capacity if the herd had been allowed to continue expanding, and a likely drop in deer population through starvation.

An even more famous example of a deer irruption was also detailed by Leopold.  The Kaibab plateau, where deer were protected from hunting and from predators, suffered a population collapse after deer consumed all available food.  This observation, common in ecology texts for decades, has recently been reaffirmed.

Washtenaw County as the ideal deer habitat

We probably don’t need to worry about deer starving to death very soon in Washtenaw County (though it is possible if current population trends continue).  We have constructed the ideal deer habitat. Not only has urban sprawl created thousands of semirural estates with landscaping, we have lush agricultural areas and lots of parks and natural areas, most restricted from hunting.  Here is what the DNR’s analysis says about our county (the entire county is a Deer Management Unit):

The landscape supports a patchwork of cover types, with agriculture, forest, and grass/shrubland being most dominant. Urban development is concentrated in the City of Ann Arbor; however this DMU supports other largely developed areas and suburban and ex-urban communities; this is a populous county and development is ubiquitous throughout the DMU. …

Although much of the private lands toward the south central parts of the DMU are in agriculture, private and public lands in the area support cover habitat for deer (e.g., woodlots, shrub/brush, and wetland). Deer throughout the Washtenaw DMU have ample access to food, water, and cover and can meet all life requisites in every portion of the DMU. However, in many cases, they may be meeting these requirements in areas closed to hunting. (emphasis added)

Cultural carrying capacity is exceeded long before adequate food is exhausted. (Missouri Extension graph)

Cultural carrying capacity is exceeded long before adequate food is exhausted. (U. Missouri Extension graph)

Here’s the problem: through our own intervention to create a beautiful and lush living space, we have created a refuge for deer, with little hunting, no wolves, and tasty food, well tended.  Being deer, they have responded with explosive growth in our living space.  (Anecdotally, the areas west of us where hunting is allowed are not overpopulated.)

So while it may take a while yet before our local deer exceed their food supply (biological carrying capacity), they will have long since exhausted our patience.  The concept of “cultural carrying capacity” expresses the total impact of deer-vehicle collisions, agricultural losses, landscape damage, and now even concern over disease-carrying deer ticks.

I’d say that Ann Arbor’s deer have reached that level already.

Note: A list of posts on this subject and some other useful resources on deer management in Michigan are found on our page, What Do We Do About the Deer?.

 

 

 

Deer and the Community Conversation

Posted February 16, 2015 by varmentrout
Categories: Sustainability

The sign-off slide from the city presentation

The sign-off slide from the city presentation

The City of Ann Arbor Deer Management Project continued with a second public meeting on February 5, 2015.   The slide presentation from the City’s consultant and a video of the meeting are now available on the City’s webpage.

The agenda consisted of four parts:

  • An introduction by Sumedh Bahl, Community Services Administrator, and Charlie Fleetham, the City’s consultant.  The survey was briefly summarized as to a few high points, though no real analysis or comprehensive summary was offered.
  • Important announcements: that there would be an aerial assessment of the deer population; and that the date of the report would be moved up to late March.  Also, that the staff and consultant would not make any recommendations, but would offer alternatives.
  • A scripted interview with Lance DeVoe, the Rochester Hills staffer who is in charge of their “non-lethal” deer management program.
  • A presentation by Christopher Graham, an Ann Arbor landscape architect who has long experience with the damage deer do to landscapes and natural areas.  He has long been a figure in Ann Arbor policy circles, and is a member of the City’s Environmental Commission.
  • A very long public comment session (half the line was still there when I left at 9:15).

Evidently the Humane Society Huron Valley Chapter was invited to speak on the idea of using contraception to inhibit the spread of deer, an idea vigorously promoted by the Humane Society US , but declined.

Rochester Hills, Michigan, has the highest deer-vehicle crash count in the SEMCOG area, but has chosen to use what is described as a “non-lethal” approach.  This mostly consists of a combination of driver education and signage, vegetation trimming and other means of reducing crashes, together with education about landscape alternatives.

Chris Graham spoke as a representative of the Washtenaw Citizens for Ecological Balance.  He spoke movingly of the loss of gardens, local food production, and damage to the very web of life in our natural areas. The WC4EB presentation slides and text of the speech are included here as pdf files, but may also be viewed on the website.  Members of the WC4EB also distributed an informative flyer.

It was apparent that the Humane Society and associated groups like the Citizens for Safe Deer Management, who have now gotten themselves recognized as a “stakeholder”, had recruited sympathizers from all over SE Michigan to come and support the “nonlethal” viewpoint.  During the long public comment period, people from as far as St. Clair Shores spoke about the moral imperative to preserve the lives of deer.  A common theme was that Ann Arbor gardeners could avoid problems by choosing to plant the right plants.  One lady, who caused something of an audience twitter by identifying herself as from “Sky-o Township”, instructed us to use Irish Spring Soap, so very 2006.  (Some gardeners tell me that the deer eat Irish Spring Soap!)

Rochester Hills

The city of Rochester Hills in Oakland County has consistently had the highest number of deer-vehicle crashes in SE Michigan.  According to SEMCOG, it was the top community in DVC for 2011-2013, with 430 DVC in those three years.  (Scio Township is the second highest, with 355 DVC.)  Attempts to solve this problem have resolved as their “nonlethal” approach.

The interview with Lance DeVoe was informative.  DeVoe is a wildlife biologist who was first employed by Rochester Hills as an environmental educator, but he now spends 50% of his time on the deer management program.  He said that RH began counting deer by means of flyovers in 1999.  Many of the deer are found in the parkland on large tracts of land bordering the Clinton River.  But there began to be problems in neighborhoods.  In response, a sharpshooting program was launched, but was stopped about a month later because of protests.  They now have the “nonlethal” approach.

  • The city passed a feeding ban ordinance.
  • Education on fencing, plants rarely damaged by deer, and deer repellents
  • Attempt to minimize deer vehicle crashes by signage and vegetation management, together with driver education.
  • A Deer Management Advisory Committee oversees the program.
  • There is continued monitoring of the size of the deer herd.
  • The deer are experiencing lethal effects, if only from automobiles.  The policy requires property owners to be responsible for removing dead deer on their own property.

The deer herd has varied in the monitored areas and DeVoe stated that it was staying “about the same” though the figures do not support that.  The handout showed 217 total deer in 2011 (last year shown) and he showed an updated graph in which 300 deer were observed in 2014, which he termed “an anomaly”.  Since most does produce two fawns, deer generally double in population in about two years and one would expect an increase in a population with no lethal events.  But in 2008, deer in Oakland County were hit with Epizootic Hemorrhagic Disease (EHD) , which is transmitted by midges and most observed in warmer than usual years.  DeVoe stated that the environment along the river was favorable for the midges and a considerable number of dead deer had to be removed.  The figures from the Rochester Hills flyovers show that the number of deer in the assessment areas were reduced in 2009 (80) to less than half what they had been in 2008 (184) (presumably the survey was done in the early part of each year).  So it appears that the deer in Rochester Hills are increasing in population, from a low in 2009 to higher than expected in 2014.

Another revealing point made by DeVoe is the effect on Rochester Hills’ natural areas.  In 2005, the residents passed a millage to acquire and maintain a system called Green Space (it has its own Advisory Board).  Their biologist now concedes that oak seedlings are gone, there are only a few remnant areas of Trillium, and the understory is essentially gone.  He said that most of what remains is Japanese barberry.

Japanese barberry

Japanese barberry

Japanese barberry (Berberis thunbergii) is a known problem invasive in Northern forests.  The Michigan Natural Features Inventory has a discussion and control recommendations for this pest.  The irony is that it is often planted as a “deer resistant” landscape plant.  But the thorns that make it deer resistant also make it very unfriendly to wander through in search of the beauty of nature.

Just to add injury to insult, apparently this shrub provides the ideal conditions for the deer tick that carries Lyme disease.  It shelters both the mice that carry the disease and the adult ticks.

In conclusion, it is difficult to see that the Rochester Hills story makes this model attractive for Ann Arbor to emulate.

NOTE: Posts and other information on Ann Arbor’s deer problem are listed on our page, What Do We Do About the Deer?

Oh, Deer – The Survey

Posted January 31, 2015 by varmentrout
Categories: Sustainability

Q-1

The results of the City of Ann Arbor’s Deer Management Project survey and their implications.

Surveys are tricky. There is, literally, a whole science to surveys to make them meaningful and useful.  In designing a survey, one should consider very carefully how the information is to be used.

Is the expressed opinion of the public really going to be used to make a policy decision? (In essence, a referendum.)

Or is the intent only to take the public temperature so that one may gauge the likely outcry over a decision?

Or are you trying to collect real data on the experience of the public that can be used in further policy formulation?

Or – least defensible – is the survey designed as a “push poll”, to convince the public so that a particular policy outcome can be justified by a “public” desire?

A notorious example of this last usage was the Connecting William Street project of the Ann Arbor Downtown Development Authority.  This was designed from the start to keep the usual noisy mob out of the way. (See Section II, “A Flawed Public Process”, in this Library Green report.) In particular, it involved a survey which omitted a downtown park as one of the options for city-owned properties downtown, and downplayed the strong public comment in support of a park.

One reason that surveys should be used cautiously is that the public doesn’t enjoy being deceived, or used.  So it is a good idea ahead of time to know how you really intend to use the results.  Quite truthfully, there are many times when it is NOT a good idea to make a survey into a referendum.  If people think you are asking their opinion, only to dismiss it, they resent this mightily. And yet, public opinion may not point to the best policy outcome.  There are times when political leaders simply have to lead, and referendum results may not acknowledge all the constraints and nuances in a particular issue.

But a survey can be a good tool to assess public reaction, if well-designed and used cautiously.  A good example is the series of surveys conducted by a professional firm on behalf of the Ann Arbor Area Transportation Authority, gauging support for a new county-wide transit millage.  After a number of false starts (we documented this at length, see the Transportation Page), the last version of this plan, with a much reduced service area, was approved by the voters of the City of Ann Arbor, City of Ypsilanti, and Ypsilanti Township.  The success of the millage vote was predicted by the last survey conducted; this enabled the AAATA Board to move ahead with confidence.  Here is the Ann Arbor Chronicle’s summary of those transit survey results.

What was the purpose of the City of Ann Arbor’s survey on deer management?  It was initiated without first providing much information about the problem.  Indeed, despite the report provided to the Council earlier by city staff, this survey seems to be designed in part to determine whether there is a perceived problem.  At times it appears to be constructed to inform the opinions of the public.  At other times, it seems to be a rather aimless fishing expedition.

The Deer Management Project Survey

The City used its survey tool called A2 Open City Hall. The Deer Management Project survey was closed on January 2, 2015. There were 27 questions in all (not numbered, though we’ll be referring to them by number).  A total of 537 responses were recorded.

The questions and summary of responses are no longer available for viewing and the outcome has not yet been posted.  However, if you took the survey, your own responses may still be viewed. See update below.

Like many online surveys, this has a flaw in that it is a self-selected survey sample.  A truly accurate survey of public opinion would be a randomized, carefully balanced sample incorporating suitable geographical and demographic ranges.  But, just like the public vote on a referendum, this counts only the people who care enough to show up.

Such a survey has a potential value in estimating the views of the public on this delicate and difficult subject.  But this survey has many deficiencies.

1. Structural flaws

Some of the questions should have been nested, where one skips questions that don’t apply.  For example, Question 7  asks,

Have your garden plants or landscape been damaged by deer?

Approximately half (51%) of the respondents answered “No.”  But then Questions 8-12 go on to ask about the effectiveness of fencing, repellents, noise-makers and other frightening devices, or use of deer-resistant plants in addressing deer damage.  Obviously half the respondents are not going to have direct experience and their opinions on whether various measures are effective can hardly be reliable.  For useful information, Q7 should have instructed the reader to skip Q 8-12 if the answer was “No”.  This is called use of “skip logic” in surveys and makes results much more meaningful.

2. Asking for expert opinions from non-experts

Questions 14-21 are prefaced by this comment:

Communities who have adopted deer management plans typically utilize a variety of measures to help minimize conflicts with deer and/or to reduce their population.

Support for several of these methods (education about deer-resistant plants, marking deer crossings, managing roadside vegetation, prohibiting supplemental feeding) is queried in a straightforward way. But what is not clear is whether these “non-lethal” methods are to be adopted in exclusion of any lethal method of limiting deer population.  Question 18 does indeed ask about approval of a lethal method, such as use of sharpshooters.  None of these questions asks about effectiveness of the one method being discussed.

Then in Q 19-21 the survey asks for expert opinion:

If the following method were allowed by the DNR, based on your knowledge, do you feel *** would be the most effective non-lethal method in resolving the perceived deer nuisance issues in Ann Arbor?

The three non-lethal methods named are deer contraceptives, trapping and sterilizing deer, and trapping and relocating deer.  There are two very odd things about these questions.

(1)These three approaches were specifically disallowed by the August report from the City Administrator, and it is generally understood that none of them are approved by MDNR at this time.

(2) Even if they were approved methods, how would Ann Arbor residents without expert knowledge be expected to have an opinion on their effectiveness? (Results indicated that most rejected the trapping and relocating option, with 72% either saying “Least effective” or “Don’t know”; for the other two options, about 35% were positively impressed, answering “Most effective” or “Moderately effective”, and 65% negative or didn’t know.)

So what was the purpose of including these questions?  Was it to plant a suggestion in the minds of the public that these might be feasible approaches?

3. Selective omission or emphasis

At the December 10 meeting, the consultant (Charlie Fleetham) showed an inclination to emphasize certain results and also announced the intention to eliminate use of the data gathered for some other questions. For the question,

In general, do you believe deer are a more valued species than other urban mammals (coyote, rabbit, squirrel, skunk, woodchuck, etc.)

he reviewed the results by emphasizing those who had answered “Yes” (at that time, 27.2%) while omitting the point that a heavy majority had said “No”.  (Final results were 139 (26%) Yes and 398 (74%) No.)  There was an audible outcry from the audience, at which point Fleetham looked out and stated rather belligerently, “Well, I think that’s significant.”  In fact, it is rather significant.  It shows that a very small minority of Ann Arbor respondents were willing to give deer a special status among all the diversity of wildlife.  But his emphasis seemed designed to make a different point.

Meanwhile, the last three questions on the survey (which were another example of asking the public for an expert opinion) were phrased in this way:

Research concludes that lethal removal measures are most effective for managing a deer population. Please indicate your level of support for *** within the city.

The three choices were for firearm hunting, bow hunting (both as part of the regular hunting season) or sharpshooters.  (No information has been given as to how such programs would be implemented.)

Image from the A2 Open City Hall survey on December 27, 2014

Image from the A2 Open City Hall survey on December 27, 2014

Apparently the local Humane Society objected to this language.  (Tanya Hilgendorf, its director, is quoted at length by the Ann Arbor News in objecting to the questions.)  It has now been stated that these questions will not be considered in the analysis of the survey.  Now, it is agreed that this was unfortunately worded.  But then, it is on a par with many of the other poorly done sections of the survey.  Will the City simply discard data because of political points brought up by one side of the question?

Useful information

In spite of its many flaws, the survey did yield some useful information.

1. Support for lethal methods

As we stated previously, a major reason for public engagement on this issue is that the use of lethal methods to manage the deer population hits on some real sensitivities.  We do have some answers on this question from the survey.  In addition to the three contested questions at the end, there was a relatively uninflected question earlier, which will presumably be retained:

Please indicate your level of support for using lethal methods such as hunting or sharpshooting to reduce the deer population

Like many questions on the survey, respondents were asked to indicate “strong support”, “moderate support”, or “do not support”.  We have combined the two figures for strong and moderate support in this analysis, since they both indicate an affirmation for the method mentioned.  (All percentages are based on 537, the total number of responses at the end of the survey.)  This table shows results from both the early general question about lethal methods and the specific questions about method.

lethalNote that when asked in general about use of lethal methods, a majority indicated support.  However, there was some uncertainty about specific methods, with “firearm hunting” receiving  little support.  Also to note here is the use of the words “within city”.  Since no details of the method are given, this could be imagined as having hunters generally roaming the neighborhoods, which of course will never happen.  This is really a very strong support for lethal methods, given the lack of specific information.

2. Nature of the concern

Another useful question was

Which of the following concerns do you have about deer in the City of Ann Arbor?

Note that the answers are not mutually exclusive in this case – this was a “check all that apply” question.  A little over 60% of respondents did have some concern.  Here are the answers, ranked.

concerns

Clearly the danger of deer vehicle crashes was the largest concern, though very few reported that they or their family members had experienced such a crash (near misses were not counted).  But what is notable here is that a substantial minority reported concern about both garden plants and native vegetation.  A similar percentage were also concerned about the transmission of Lyme disease and other deer tick-borne diseases.  It is interesting that the stated concern about decline in the health of the deer themselves was at nearly the same level.

Where do we go from here?

The survey, flawed as it is, does indicate that there is a perceived problem with the burgeoning deer population in Ann Arbor.  It may be possible to obtain slightly more information if the analysis includes techniques such as comparing an individual respondent’s answers on certain questions.  For example, how does the belief that deer are more worthy than other wildlife influence answers on some other questions?  As of January 31, 2015, no summary analysis has been posted.

The Deer Management Project page on the Ann Arbor city website states that a report will be presented to Council on March 2, 2015.  There are very few indications of what information is being gathered in the interim.  Another public meeting is scheduled for February 5, 2015, 7 p.m. at Slauson Middle School, 1019 W. Washington.  According to the City press release, a review of the survey results will be presented at that time.

Note: Posts on this subject and other resources are listed on our page, What do We Do About the Deer.

UPDATE: The survey summary is available on A2 Open City Hall. Go to Closed Topics and choose the deer project.  Choose the Feedback tab.

open city hall tab

Click on the Download PDF hyperlink.  You will have to supply your email address and a pdf will be sent to you in time.  The CSV download is not useful – it is a record of all responses, not summarized.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


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