Do we have too many deer?
Experts agree: We do not have a deer overpopulation problem in Ann Arbor.
Ecologists and wildlife biologists say that if there were truly overpopulation, in the sense of overburdening the habitat, deer would starve en masse, as occasionally occurred decades ago when winters were more severe and browse was less available. Does would no longer have twins, and deer numbers would drop within a year. But Ann Arbor's deer aren't overburdening the habitat-- they're healthy and eating plants, which is why some are upset at them. They know we do not have an overpopulation so they use the unscientific and subjective term "overabundance" when they say how many deer there are.
The problem is not "too many deer," but rather "too many deer where some people don't want them to be."
And though we can sympathize with gardeners' and landscapers' concerns about deer in their backyards, culls don't solve the problem-- and can worsen it. Cullers cannot guarantee the removal of specific deer deemed nuisances, and if choice landscaping/food sources remain accessible, deer will continue to thrive on them.
Scientific studies indicate culling can increase birth rates.
Culling only lowers deer numbers on a temporary basis, which is why it must be done year-after-year. Fairmount Park started a "one-time" deer cull in 1999; they're now on their 15th year of culling. Jackson is on their 8th.
Reproduction is density-dependent; as the total deer population decreases, the average number of offspring increases. After culling in Chicago's metro area, ecologists were dismayed to find that does in these culled areas were more likely to reproduce at a younger age, more fawns were born and more survived. Scientists in Florida have found hunted deer herds are much more likely to produce twins.
When deer populations are unnaturally reduced (e.g., through a cull), yet resources remain, the remaining deer and those who move in to take those resources are better-nourished. Better-nourished deer have higher productivity, lower fawn mortality, increased conception rates, and increased pregnancy in young deer--thus helping the population grow unnaturally faster.
Michigan DNR remains "neutral" on a cull in Ann Arbor. Perhaps that's because they say deer numbers are declining in Michigan.
The Quality Deer Management Association (QDMA), a national group of hunters, suggests that deer populations are declining across the US, and that Michigan's deer harvest has declined 20% from 2003 to 2013.
The Michigan Department of Natural Resources (MDNR)'s 2014 Deer Management Overview for Washtenaw County says, "It does appear that deer herd condition declined in the Washtenaw DMU [Deer Managment Unit] from 2003-12. Increased deerdensity resulting in heightened intra-species competition and resource depletion can cause this phenomenon. However, as most of our deer population indices point to a decline in deer numbers, this seems unlikely to be the cause. Also, environmental influences (e.g., extreme weather events) tend to be short in duration and impacts are limited to short time frames (i.e., 1-2 years). We would not expect to see environmental effects drive down deer condition for this time span, although climate change may be shifting this perspective. Most likely, the reduction in deer condition is mainly attributable to land use changes. Increasing development across the DMU often can help increase survival of deer using nonhuntable lands as refuge, but it may come at a price of natural vegetation resources."