Truth: There is little data on deer damage in our city.
In the Council Agenda Responses (8/18/14) there's this:
When asked about other Ann Arbor-specific data used in their decision-making, Council Members report an unpublished study on the Bird Hills park (1 of Ann Arbor's 158 parks) that sites deer browsing on saplings. The Bird Hills study is published on the website of the pro-cull group, but the study has not been published on the City's deer management page.
The published Bird Hills Nature Stewardship plan has many recommendations for preservation of the park, but does not mention deer management.
Ecology is complex. Like humans, deer both harm and help the environment.
Founded in 1982, the Highstead Foundation's mission is to conserve the forested landscape of New England through science, sound stewardship, and collaborative conservation. They've had a long-term ecological study on deer impact that has been running for 17 years.
To study the impact deer make on our forest, Highstead set up deer enclosure pens, preventing deer from accessing a specific area. They monitor the vegetation, diversity of plants, tree regeneration, plant abundance and more. They report findings without bias for or against deer.
"[Deer and the forest have a] complex and not very straightforward relationship," says Highstead ecologist Ed Faison. "Some exotic species benefit from deer browsing and some do not. Japanese barberry does better in areas where deer can graze, but burning bush and oriental bittersweet do better protected."
The Highstead Foundation's long-term study has found that there is a greater diversity of native shrubs where deer do not browse, but a greater diversity of native herbs where the deer browse. Find more information on their studies here.
A 41-year long study of national parks in Ireland published in the Journal of Forest Ecology and Management found that grazing deer are good for diversity, and that if deer are shot in annual culls, the forest becomes significantly less diverse. Deer prevent some plants from taking over the valuable ecosystem.
"Our results certainly have implications for the management of these woodlands as future policy should focus on managing deer - rather than simply excluding them - as part of the overall biodiversity objective," said researcher Dr. Miles Newman.
The researchers added: "Woodland ecology, it seems, is a little like life - it's often best to do things in moderation."
It's also important to note that deer, like many other species, are responsible for dispersing endangered plant seeds like trillium.
A deer cull could have consequences we won't like.
In an Ohio study which excluded deer from one plot, and included deer on another, they found more salamanders, snakes, and gastropods as well as more species or "invertebrate richness" higher in the plots where deer were allowed. Researchers say, "Our findings suggest that management actions taken to regulate deer densities could have the unintended effect of reducing local animal diversity."
"By just reducing the number of deer in the forest, we're actually indirectly impacting forest ecosystems without even knowing the possible effects," said Katherine Greenwald, wildlife management researcher.
In 2006, the USDA culled massive numbers of gulls around Kennedy Airport. Yet bird strikes continued. What happened? Geese moved in. The habitat was perfect for them — an unintended consequence of culling. They were back to square one.
Ecology is complex. One species solutions are simple... yet ineffective.
In a 28-year longitudinal study in southwestern Ontario, Canada, researchers monitored changes in a large forest. From 1981-1996, deer density reached a peak of 55 deer per square kilometer; they reduced it from 1996-2009 to 7 deer per square kilometer. Despite this reduction in deer density and browsing, and even after allowing what they deemed sufficient time, the trees that were expected to regenerate did not.
Of course, Ann Arbor is not a forest, and we have a low deer density, but this study points out that if we're concerned about trees, we need to look at something bigger than just deer.
More and more communities that have done culls on various species are recognizing culls are ineffective (a hard thing to admit). Canada says culls are not effective for dealing with coyote populations. The UK has concluded badger culls were ineffective.
Council Member Warpehoski's blog post entitled, "Deer Herd Management: A vote for the ecosystem as a whole," says, "to do nothing [about deer] is to choose one species over others [i.e., deer over trillium flowers]." But isn't managing deer choosing one species over another as well?
Manipulating nature to favor one species has historically caused the endangerment or extinction of another species. Nature manages itself through habitat size, availability of water and food, natural predators, and weather conditions. Of course, humans play a role in nature as well. According to the Federal Endangered Species Act, the two major causes of extinction are hunting and habitat destruction.
If we're still interested in a single-species solution, perhaps we should look at the species that scientists agree has done the greatest harm to ecosystems: humans.
How do we deal with wildlife in modern times?
Very little in today's world remains untouched and "wild." Urban sprawl has destroyed wildlife habitat. Wanting to "get back to the way things were," when deer were rarely seen is impossible; we cannot turn back the clock, we can only move forward and we need to think of wildlife issues in modern times.
Traditionally, we have discussed individual species and their benefits or detriments to us. However, this species-specific approach is short-sighted and ignores the broader issue. The UK has issues with badgers, Australia has issues with kangaroos, and we have issues with deer. In some areas of the US, there are issues with wild boars, steers, racoons, and more... Instead of approaching these issues species-by-species (as we're bound to run into more as we continue to expand the human species), we would be best served by developing a horizontal, cross-cutting approach reflecting all the various human and wildlife interests at hand and a model for our dealing with wildlife in general.
"Whether it is the badger cull, controlling deer overpopulation, maintaining feral cats, or the much wider task of wildlife law reform, effectively addressing the issues requires less focus on whether specific animal species are “good” or “bad,” and more attention broader question of how to properly address human relationships and interactions with all forms of wildlife. Getting that balance right and addressing each of the various perspectives is the challenge for wildlife management, reform, and legislation for the coming century." - The Journal of Animal & Natural Resource Law
What can we do now?
If we're concerned about the environment, we must look at all decisions holistically. For instance, at the same City Council Meeting in which the deer cull was approved, there were numerous discussions of new development in the City-- and some on green spaces and wetlands. Constituents expressed concern only not only the additional traffic this would create, but also at what would happen with the wildlife who reside in that space. Where will they go and what will they do?
For homeowners who consider deer on their property a nuisance, there are a variety of deterrents -- from sprays to physical barriers and even dogs. Deterring deer from eating human landscaping can also decrease the population of deer, as deer reproduce less when they receive less food.