(Published in the Princeton Packet, Oct. 18, 2011)

At a time when America, both nationally and locally, is often paralyzed by division, it’s worth taking a look at instances where divisiveness was overcome and an effective policy was carried out. One program that has managed to successfully navigate Princeton’s opinion-filled waters is the township’s management of the deer herd.
     When I moved to Princeton in 2003, deer were a common sight, even in the borough. Casually crossing the street in front of us as we walked to my daughter’s daycare, they were like rogue landscape crews making unsolicited house calls. Given enough time, they might have evolved bricklike patterns on their fur, the better to blend in while feasting on foundation plantings.
The next year, we were both flattered and dismayed to find them making frequent visits to our backyard on busy Harrison Street. Some had what appeared to be earrings, which we later learned were identification cards for an experimental contraception program. It seemed appropriate that Princeton deer should have special ornament.
            There was pleasure in having such beautiful, iconic creatures walk among us, but the downsides had begun accumulating with the deer. Township records extend back nearly 40 years, and show a steady increase in deer-automobile collisions. 33 roadkill in 1972 grew to 342 in 2000. Incidents of Lyme disease, which deer help to spread, were increasing dramatically statewide.
            A common explanation for increases in deer numbers is that land development is displacing them. “They have nowhere else to go,” one often hears, as if deer numbers would naturally stabilize if only development were stopped. But several factors undermine this explanation, one being simple mathematics. A doe can bear two young each year under favorable conditions. The suburban landscape, moreover, is not the habitat of last resort, but in fact serves the deer well, offering abundant edge habitat and evergreen shrubs to eat through the winter.
            Deer become numerous because we have long since banished predators like wolves and cougars that once kept deer numbers in ecological balance. The consequences of this lack of checks and balances go beyond the most common grievances about increased collisions, disease, and garden depredation.
Ask land stewards what the biggest threat to biodiversity is in New Jersey, and the typical answer will be deer. Though habitat fragmentation, invasive species and historical factors like plowing all play a role, it is the capacity of overabundant deer to collectively decimate native plant species that has greatly reduced the ecological functionality, and beauty, of our woodlands. Deer literally eat the forest’s future, be it tree seedlings or wildflowers attempting to form seeds.
The void in the woods left by deer’s preferential consumption of native plants has been filled by largely inedible exotic invasive species, greatly diminishing food options for wildlife.
            Having removed the predators that historically kept deer numbers in balance, we are left with the responsibility to step up and fill that lost link in the foodchain. Hunting is the usual approach, but though hunters were taking more than 200 deer each year by 2000, Princeton’s deer herd was still growing. The township finally made the controversial decision to hire professionals to increase the annual harvest. The increased killing, particularly the net and bolt technique used where proximity to neighborhoods precluded sharpshooting, elicited some passionate protests covered by NPR and the New York Times. The township persevered, however, and after ten years of professional deer management it’s possible to assess the results.
            Most notably, consistent governmental action has led to reduced overall killing of deer. In the last year before professionals were hired, traffic accidents and hunting killed 555 deer. Over the next ten years, the combined annual total of hunting, professional culling and traffic accidents steadily declined to 290 in 2010. The annual cost of hiring professionals also declined as the deer herd was brought down to more ecologically healthy numbers.
As deer numbers have declined, Princeton’s open spaces have undergone a botanical and ecological renaissance of sorts. Native shrubs like spicebush, previously gnawed to the ground, have rebounded to once again provide food and cover for migratory and nesting birds. Wildflower species that had all but disappeared from our woods are now reappearing.
After 2010, the township ended the professional culling for one year to see if bow hunting alone could control the deer herd. The results were disappointing, with deer numbers quickly rising. The option of contraception, still discussed, has proven expensive and impractical, particularly given state regulations. 
             This year (2011), professional management will resume. The cost, around $60,000, can be thought of as the cost of ecological services formally provided for free by natural predators. It is also one of the ongoing costs of protecting Princeton’s substantial investment in open space. The harvested deer are donated to local food kitchens, where the meat can be eaten knowing that the deer lived a better, free-range life than any cow or chicken for sale at the local grocery store. What little health data I was able to find show a significant drop in Lyme disease in Princeton, contrasting with increasing rates elsewhere. And while dissent can help insure that the harvest is as safe and humane as possible, Princeton can look with some satisfaction at having collectively and effectively confronted a problem that was collectively created.
--Steve Hiltner

Update, 2023: A detailed description of the deer culling program appeared in the Princeton Packet in 2021.