ANN ARBOR, MI - Protecting the city's natural areas is cited by Ann Arbor officials as a primary reason for bringing in sharpshooters to kill hundreds of deer in the city.



Deer are causing too much damage to native vegetation such as oak seedlings with their eating habits, city officials argue. And if there's too much destructive munching, which city officials believe to be the case, it can potentially hinder forest regeneration and biodiversity.



But in order to protect the city's forests, city officials acknowledged this week the city is cutting down trees to clear areas to shoot deer.



The city's third-annual deer cull is underway and some residents are concerned about seeing trees reduced to stumps where shooting is occurring.



"I find it ironic that one of the reasons for the cull is stated to be to 'protect the understory from the deer,' yet the shooters hired by the city are destroying the understory with chainsaws and apparently with abandon," said Terry Abrams, a member of Friends of Ann Arbor Wildlife in Nature, a group that opposes the cull.



Abrams said he was shocked the other day to see several trees cut down in the Narrow Gauge Way Nature Area, one of the shooting zones for the deer cull in northeast Ann Arbor. He said he counted more than 15 trees that were cut and he took photos of them.



"Many were in the vicinity of bait piles, but some were along the stream not near the bait," he said. "The trees were of various sizes, as you can see in the photos, and fresh sawdust was in the snow."

Shooting is taking place in many city parks and nature areas throughout the city, as well as other properties such as Nichols Arboretum.



Tom Crawford, a member of the city's administration overseeing the deer cull, acknowledged trees are being cut down for the cull.



"The city's Natural Area Preservation staff does cut and trim smaller trees in preparation for effective and safe culling operations in designated parks and natural areas," he said.



"This practice has occurred in years past. City staff are utilized to ensure appropriate trimming and cutting is performed."



10 things to know about the 2018 deer cull in Ann Arbor

City officials did not provide any information about how many trees have been cut down, what types of trees have been cut down and in which areas they've been cut down.



City spokeswoman Lisa Wondrash said the city does not keep an inventory of that type of information.



"As noted, this work was done by NAP staff to ensure appropriate trimming and cutting was performed, therefore an inventory wasn't necessary," she said.



During the city's first deer cull in January 2016, some residents raised concerns that several bushes and trees were cut down in Bird Hills Nature Area, one of the shooting zones, and they believed it was done to create a clearing to shoot deer. Asked at the time if trees were being cut down in Bird Hills or any other nature areas to carry out the cull, Wondrash said in January 2016 that was not true.



Crawford's statement this week now indicates it is true that the city cut trees for the purpose of culling deer in years past.



Jacqueline Courteau, a local ecologist and biologist, has been closely studying the impacts of deer in Ann Arbor's natural areas since the fall of 2015, hired by the city to conduct a study of hundreds of newly planted red oak seedlings in forested areas -- half of them fenced to assess survival without deer, and half unfenced.



What she found through her initial research, which was reported in October 2016, was that 54 percent of the unfenced seedlings were browsed by deer at least once, and half of the sites had 60 percent or more seedlings browsed at least once.



Courteau cited Cornell University research suggesting an oak seedling might take 10 to 20 years to grow out of reach of deer under a forest canopy, and more than occasional browsing -- or damage to 15 percent of seedlings in any given year -- indicates deer populations may be too high. As noted by Bernd Blossey, an associate professor from Cornell, Courteau said, tree regeneration declines when more than 15 percent of seedlings at a given site are browsed per year.



"Ecological concerns about the impacts of deer on natural areas go beyond assessing whether deer are damaging a few plants," she wrote in her initial report. "The larger and deeper issues are whether deer damage is leading to declines in biodiversity -- in the abundance and distribution of native species -- and whether that damage can lead to long-term changes in ecological communities and functions."



Courteau submitted a 28-page report to the city last April with updated information regarding the oak seedlings and deer browse levels. She said red oak is a species of "intermediate" deer preference, so it's not the first and most nutritious food to be browsed by deer and doesn't represent the most sensitive species, but it's also not the last food.



"Because this species is not highly preferred, it offers a somewhat conservative indicator," she wrote.



Browsing on oaks is correlated with damage to wildflowers, but is easier to identify and assess, Courteau said.



Courteau said 370 red oak seedlings were planted in 10 city park natural areas from Nov. 30 to Dec. 16 in 2015. Separately, she said, the University of Michigan contracted a study of deer impacts in Nichols Arboretum with 50 red oak seedlings.



Courteau's report shows results for both studies with a total of 420 seedlings -- half fenced, half unfenced. Monitoring occurred from January 2016 into January 2017.



She concluded seedling mortality where deer were allowed to browse was 44 percent, compared to 20 percent for fenced controls.



Courteau said unfenced seedling mortality ranged from 30 percent to 56 percent by site, and from zero to 35 percent by site for fenced seedlings, except at Fritz Park where both fenced and unfenced seedlings had a mortality rate of 70 percent.



According to Courteau, deer browsed 61 percent of the unfenced oak seedlings in the experiment at least once.



"Browse damage ranged from 20%-90% across sites," she wrote. "More than half of the sites had 60% or more seedlings browsed. Browse of more than 15% of seedlings per year is likely to interfere with forest regeneration (Blossey 2014)."



She said browse intensity (repeated browsing) was highest in Bird Hills, White Oak, Furstenberg and the Arb.



Some seedlings were browsed by both deer and small mammals, Courteau reported. And in many cases where that occurred, she said, rabbits browsed seedlings over the winter, the seedlings re-sprouted in the spring, and then deer browsed the "resprouts."



While deer browse may affect many wildflower species that are of interest for their ecological importance -- such as providing resources for pollinators including bees and butterflies, and various species of birds -- the advantage of studying a woody species such as red oak, Courteau said, is that deer browse damage on woody stems can be readily distinguished from browse damage by other mammals.



"Numerous studies over the past two decades have reported that deer browsing leads to forest regeneration declines," she wrote. "Although many plant species can tolerate moderate levels of herbivore damage, deer browse on woody plant buds and branch tips is likely to affect the apical meristem tissue key to plant growth."



She said browse damage makes seedlings more susceptible to drought, disease and insect attacks and can lead to an increase in mortality in the following season.



Courteau submitted another seven-page memo to the city last September, discussing the research methods more, acknowledging there are some challenges when looking at browse rates.



She said deer browsing on red oak seedlings may vary for many reasons, including weather and availability of other food sources, so it may take several years of trend data to distinguish natural variability from response to changing deer populations.



"Another challenge is in interpreting what the metric - proportion of seedlings browsed - indicates for management actions," she wrote in her September memo. "What is the target? What is a tolerable level of browse, and what is a level beyond which deer populations should be managed? Blossey et al. (2014) suggests that oak regeneration is likely to decline when more than 15% of oak seedlings are browsed per year (3 of 20 planted seedlings)."



Tracking seedlings planted in Ann Arbor over time, Courteau said, will allow an assessment of whether local browse rates allow for successful oak regeneration. In the meantime, she said, the 15 percent threshold level is the best available target metric given the existing research literature on oak regeneration.



"Long-term studies tracking deer browse damage on red oaks for 20-30+ years from germination to reproductive maturity have not been done that could experimentally demonstrate 15% as a 'not-to-exceed' level of deer browsing," she wrote. "Blossey's 15% recommendation is inferred from growth rates and survival of browsed vs. unbrowsed oak seedlings over two to three years as published in peer-reviewed literature (Blossey et al. 2017)."



In addition to damage to natural areas, Ann Arbor officials have cited damage to people's private landscaping and gardens, as well as deer-vehicle crashes, as other reasons for the deer cull.







