Archive for the ‘Sustainability’ category

Bagging the Plastics Ban: Washtenaw County’s Never-was Ordinance

January 4, 2017

no-plastic-bagsIt was one of those great outrages.  In the closing days of the 2016 session, the Michigan Legislature killed any possibility of Washtenaw County’s attempt to regulate plastic grocery bags.  “Ban on local plastic bag bans now Michigan law”, reported MLive. Outgoing State Representative Jeff Irwin decried this defeat for local control.  This was seen as another case of Republican domination of progressive Michigan municipalities (cities and counties).  A few days later, another news account stated, Washtenaw County concedes it can’t enforce disposable bag ordinance.  The bill (Senate Bill 853)  is succinct but also thorough: it mentions regulation of any “auxiliary container” of almost any composition as being forbidden for local units of government.  (There goes any hope of banning styrofoam clamshells.)

But the story is more complicated than it appears at first and there are some questions.

Washtenaw County’s ordinance is the only such regulation in the State of Michigan.

As explained in this memo from Water Resources Commissioner Evan Pratt to the Board of Commissioners’ Ways and Means Committee last May, the existence of Senate Bill 853 was already understood at the time the BOC passed the ordinance.

Senate Bill 853, currently pending in Michigan legislature, seeks to withhold local government authority to regulate “auxiliary containers,” a category within which carryout grocery bags falls. If SB853 is adopted by the State of Michigan, it would act to preempt a County bag ordinance. Washtenaw County seeks to retain its local authority to regulate the material in furtherance of its duty to optimally manage solid waste within its geographic boundaries, and to increase Washtenaw County’s recycling and waste economy to full extent possible.

The motivation for adopting an ordinance in the face of a likely preemption by the State is unclear. Are we trying to make a point or hoping that it will survive to be enforced?  That expression about “seeks to retain its local authority” seems to argue the first.

In spite of most indications, the ordinance is not just about plastic bags. It also applies to paper bags.

The proposed bag ordinance is not a ban.  And it sanctions disposable paper bags just as much as plastic bags.  This although almost all the educational material about the ordinance specifies plastic bags.  The slide show on the ordinance given to the BOC in a work session is all about the hazards of plastics.  The memo that accompanied the resolution stated that it was about “a policy to combat the problems caused by excessive plastic bag waste in our community”. The resolution setting the public hearing on the ordinance mentions only plastic bags.  And yet the ordinance cracks down just as hard on paper grocery bags.

Did the Commissioners know what they were passing?

ugly-plastic-bagNow, it is hard to love plastic grocery bags. They are ugly, consume valuable unrenewable resources, are a hazard to animals, glob up machinery of recycling plants, and last longer than the human race.   They actually cost the County and other units of government money. They are difficult to recycle even when collected.  Surely no one who cares could object to banning them, and in fact this was a very popular idea.

Paper grocery bags are another matter.  Many of us reuse these bags many times or at least once. They compost. They are recyclable. They are most often made from recycled paper.  No, they are not a “zero footprint” item but just not in the same class as a plastic bag.  Besides, that is not how this ordinance was being sold.  Yet, they are being treated exactly the same as plastic bags in the ordinance.  The indication is that customers should bring reusable bags (most often cloth).

The whole enterprise has a rather unpleasant air of bait-and-switch.  Don’t like plastic bags? Fine, and also you can’t use paper bags (hidden in the fine print).

It suddenly seems to be about money.

Here’s what the ordinance does.  It imposes a ten cents fee on the consumer for each plastic OR PAPER bag used.  Of that, 8 cents goes into a new fund (the Stewardship Fund) that the County has created.  The retailer gets 2 cents, which is to be used only for enforcing the ordinance.  There are also civil infraction fines for retailers who do not cooperate.

What this does is to create a monetary incentive for the County for consumers to use plastic bags (or paper).  You rush into Meijer to buy some milk and bread.  Cashier says “it’ll cost you 10 cents per bag”.  You say, “whatever”.  Out the door.  It actually incentivizes the retailer to keep on providing these bags too.  I can’t imagine the County sending around deputies to check on the quality of their environmental education efforts. The cost to the retailer for providing plastic bags is less than for paper bags, but they get to keep the same fee.

So how effective would this have been in preventing use of plastic bags? My estimation is, not very.  If your budget is very, very tight, you might sweat those couple or five dimes.  Or you might remember to bring bags whenever you have a big shopping to do.  (As far as I can tell, no forgiveness for simply reusing old paper bags, either.  The ordinance imposes conditions on the “reusable bag” that may be used.)  Mostly, it would just be an additional cost that most consumers would pay at checkout.  And money would go to the County.

It is hard to escape the thought that this might be a way to raise revenue for the County’s solid waste endeavors as much or more than actually changing behavior on bags.  Those fees would add up.  Do you know how hard it is these days for counties to get money?  And the Washtenaw County solid waste program used to be dependent on tipping fees from the Salem Township landfill.  I don’t know how that is going these days.

By the way, I think the fees may not have passed the test of the Bolt decision.  Michigan municipalities are not supposed to impose new fees unless they are related to the delivery of a specific service.  I don’t see how this qualifies.  One of those sticky only-in-Michigan constitutional issues.

If only…

What might have worked?  There are many examples around the country.  If the County could have simply banned use of plastic bags (and it does ban some things, like smoking in workplaces), that would have achieved the stated objective more simply and effectively.  For reducing waste due to paper bags: many retailers even now give a 5 cent credit for each bag you bring in.  Depending on the market, they could increase that to 10 cents and raise their prices slightly. That is essentially the same as charging 10 cents for use of a new bag.

Good legislation should achieve its stated goal without being any more intrusive than necessary.  This did not pass the test.

Meanwhile, let’s lean back and blame it on the Republicans.  They probably deserve it.



So Where are We Now with Ann Arbor’s Deer?

December 30, 2016

The last three years have been the Early Period for Ann Arbor’s deer debate.  Now there is a coherent plan for deer management and a page containing historical documents on the Ann Arbor City website – quite a long story.  We posted extensively about this issue through 2015.  Those posts and other articles and resources may be found on our page, What Do We Do About the Deer.  2017 will be busy. In a special session on November 14, 2016, Council approved several resolutions to make the management plan operable.   According to the Ann Arbor News, officials are still awaiting permit approvals by the Michigan Department of Natural Resources (DNR).  Maps showing where a sterilization program will be conducted have also been published.

For several decades, the white-tailed deer have been appearing around the edges of the city. But as of early 2014, they became numerous enough to be real pests.  As the numbers of the animals began to intrude on more and more human lives, there was an organized effort to limit their effects on gardens, natural area vegetation and automobile crash incidents.  Their impact on parks and natural areas in Washtenaw County was recognized by the WC Parks & Recreation Commission in early 2014. In May 2014, Ann Arbor’s City Council directed the City Administrator to prepare a report on deer management in partnership with other entities.

Numbers of DVDs in Ann Arbor City between 2005 and 2015. Source: Michigan Traffic Crash Facts.

Numbers of DVCs in Ann Arbor City between 2005 and 2015. Source: Michigan Traffic Crash Facts.

As the account in the Ann Arbor Chronicle about that Council meeting indicates, one impetus to raising the problem of the increasing deer population was the slow increase in the number of deer-vehicle crash incidents.  These are reported in Michigan via a website, “Michigan Traffic Crash Facts“, whose data is from safety (law enforcement) personnel.  (There is always a delay after the end of a calendar year in publishing the totals for the previous year, so as of today’s writing we must wait for a couple of months before we know the totals for 2016.)  By 2014, DVCs in Ann Arbor had increased by 30% from the previous decade.  Last year, there was a major jump in numbers of crashes.  We’ll be watching to see if 2016’s number indicates a trend or that this was an aberration.

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

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

So why do we need a deer management program?  Because of their explosive reproductive capability.  As we explained in detail in our post, Deer and the Numbers Explosion, deer will increase their numbers exponentially if left unchecked.  In the early years, one only notices that there are more deer around than in the past.  Suddenly 10 deer are camping out in your backyard.  This increase in numbers has many effects on the immediate territory.

The common white trillium is used as an indicator of deer herbivory. Photo by B. Ball, courtesy of the UM Herbarium.

The common white trillium is used as an indicator of deer herbivory. Photo by B. Ball, courtesy of the UM Herbarium.

  1. Plant herbivory: Most plants (or at least their edible parts) are consumed.  This causes damage to gardens and landscapes, and natural areas where native plant communities are being maintained are severely altered. As we explained in Deer and the Flowers of the Earth, wildflowers are beautiful and a source of delight for visitors, but they are also extremely important in the survival of the entire wild community.   Plants are “foundational” in a wild ecosystem and without them, nothing lives, even the deer.  Fifth Ward councilmember Chuck Warpehoski has expressed this beautifully in his recently updated post.
  2. Deer-vehicle crashes: As we have already noted, DVCs increase with increasing population.  To date, we have not had any crashes locally where a human has been killed, but there has been considerable dollar damage to automobiles and the potential for human injury is certainly there.
  3. Lyme Disease:  Deer have a complex relationship with this disease.  They provide a blood meal for black-legged ticks, the vector for this bacterial disease, and help carry the tick into new territory.  Also, their plant herbivory often favors an understory full of Japanese barberry.  Deer don’t eat this thorny shrub and it provides an ideal habitat for the white-footed mouse, the main host for the tick.  Mice multiply under the canopy of the low shrub and help carry the tick and its bacterial rider into new territory.

Lyme disease is known as an “emerging disease” in Michigan.  It has been moving into new areas of the state. When the deer problem was first highlighted in 2014, it was thought to be a couple of counties west of Washtenaw.  Now there are recognized cases in our county.  We are all at risk.   I hope that our governments provide adequate education so that people can recognize the disease and seek immediate treatment.   Here is a good place to start.


UPDATE:   The City of Ann Arbor has now posted an explanation of the 2017 deer management programA somewhat more easily accessed account was published by MLive. 

Here is the deer management map.  Note that some residential areas are targeted for participation in the nonlethal program. Also note that without fanfare, some UM properties have been included in the lethal culling program.

SECOND UPDATE: The University of Michigan made some of its properties available for the cull for the first time this year, eliciting some cries of anguish from the opposition.  Here is an explanation from the University Record of the program from the UM perspective.

THIRD UPDATE: On March 8, 2017, there will be a lecture program addressing the problem of deer herbivory from an experimental and data-oriented viewpoint. The two presenters are both experienced with direct testing of deer-wild flora interactions.  Jacqueline Courteau is a wildlife biologist and consultant, and Paul Muelle has been the manager of natural resources at a major park (Huron-Clinton Metroparks) through a time that culling and vegetation assessment have been practiced to maintain the parks’ resources.  Here is the full announcement about the talk.  It will be at the Matthei Botanical Gardens, 6:45 p.m. on March 8.

Ann Arbor Deer: The Survey

April 10, 2016

The City of Ann Arbor is soliciting feedback from residents about the deer management program.  The questions are simple and direct.  (Apparently this year the City sought some expert advice.)  It doesn’t take long.

The survey is important because it will provide data not only about attitudes but also the actual experience Ann Arborites have had with deer.  These data will be valuable in assessing the deer-human interface – an important question when trying to estimate what population of deer in the city is too much.  The survey also contains questions about methodology – a lethal cull as was conducted this year, or an experimental approach using contraception.

Here is the announcement of the survey, with a link to open it up.  You’ll need to register with Open City Hall in order to have your response counted.

The deadline for answers is April 29, 2016.  Hurry!

Note: A compendium of blog posts on this subject, reports from other media, and general reference material is found on our page, What Do We Do About the Deer?

This summary page is updated continuously.

Deer and the Population Problem

August 4, 2015
Nine deer winter 2015

Deer in an Ann Arbor back yard, winter 2016

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 LegistarUPDATE: Here is the text of the resolution as amended.  The Council voted 8-1 to conduct a lethal cull in winter 2016. Mayor Christopher Taylor opposed this. The resolution was amended to indicate that the City would also cooperate with a study of sterilization or contraception if practicable.

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

UPDATE, January 2016: Ann Arbor is now conducting a lethal cull of 100 deer in 14 city parks.  City Council passed several enabling resolutions, listed here.

For more updates, visit our summary page, What Do We Do About the Deer?

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).

SECOND ADDENDUM: Local author and journalist Margaret Leary has compiled a summary of deer-vehicle crashes over the last 10 years. She also calculated the percentage of vehicle crashes related to deer.  Sure enough, the percentage has increased over the time period.

dvc data

THIRD ADDENDUM: Data obtained by the former editor of the Ann Arbor Chronicle (Dave Askins) indicates that the number of deer-vehicle crashes has shot up dramatically in the last year, to 88 total reported in Ann Arbor.

Deer-vehicle crashes in Ann Arbor 2005-2015

Deer-vehicle crashes in Ann Arbor 2005-2015

Deer and the Flowers of the Earth

May 31, 2015
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   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

March 26, 2015

“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.

SECOND UPDATE: Chuck Warpehoski, a council member from Ann Arbor’s Fifth Ward, has written an excellent essay on why he voted to control the local deer population by means of a lethal cull.   It highlights the damage to the ecosystem in natural areas. Deer Herd Management: A vote for the ecosystem as a whole

Deer and the Vacuum Effect Fable

March 8, 2015

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