by Carlene Phillips ·
Friday, March 14, 2025
As spring approaches and Harvard gardeners look forward to emerging plants, so too do they dread the arrival of the white-tailed deer who dine on the tops of those new shoots. The issue of how humans relate to nature and deal with increasing populations of wildlife in suburban spaces is a complicated one, both scientifically and emotionally. To share insights and expertise on the topic, Allen Rutberg will speak at the Warner Free Lecture, 7 p.m. Friday, March 21, in Volunteers Hall.
Rutberg’s research at Tufts University, where he is an associate professor in the Department of Infectious Disease and Global Health and director of the Center for Animals and Public Policy at the Cummings School of Veterinary Medicine, has focused on the efficacy of using contraceptive vaccines to control overpopulations of white-tailed deer and free-roaming horses. In a phone conversation, Rutberg said he and his colleagues have had quite a bit of success using the vaccine to reduce the deer and wild horse populations in parts of the East Coast.
The vaccine can be useful in controlling the population of wild horses on the barrier islands along the Atlantic coast but even more so on public lands in the West that are used for cattle, mining, and recreation. The horses are protected, have no serious predators, and take a big share of the food. It is hard to manage them, and it stretches resources to round them up, remove them, and try to get them adopted.
Dr. Allen Rutberg with a furry friend. (Courtesy photo)
For 100 years, said Rutberg, hunting controlled the deer population on the East Coast. But now deer are everywhere, thriving in suburban landscapes where hunting “doesn’t do a great job” and in many places is impossible. Fieldwork in Fripp Island, South Carolina, and Hastings-on-Hudson, New York, has shown a 50% reduction in deer population over five years, and the effect is noticeable. But, said Rutberg, “It’s a lot of work.” The vaccine is injected into females by a dart, shot at 25 yards. One shot works for two to three years, and a booster extends the effectiveness, though it isn’t known for what length of time. The problem is in knowing which deer you’ve “darted,” said Rutberg. Unlike wild horses, all female deer look the same and the only chance of identifying them is that they tend to remain in the same areas. Using a catch-and-tag method is time-consuming and expensive, involving the use of veterinarians.
Beside the scientific challenges is the issue of public response. Society struggles with how to think about the deer and how to live with them. Most people like deer but don’t really want them in close proximity. It’s like the neighbors you like but who play their music too loud, said Rutberg. There has been hostility from hunters who believe using contraceptives is unnatural and intrusive. It “emotionally rubs them the wrong way” though it doesn’t reduce the population that much, Rutberg said. For many people it is a totally foreign concept to manage wildlife with contraceptives.
Rutberg said we make “shorthand connections” between problems and nature. Most of us don’t think seriously about plants and animals. We put them in boxes, which removes the opportunity to explore the complexities. Anything named “pest” dictates action, which usually means killing. Some plants and animals that we name “invasive” actually fit in.
Growing up in New York City, Rutberg did not know anyone who was interested in nature. He spent a lot of time in the woods, but it wasn’t until graduate school that he learned anything about being a naturalist. He had always been interested in animals and their behavior and received a Ph.D. in zoology from the University of Washington. His plan was to have a career teaching biology and doing research, but after seven years doing that, he became a wildlife advocate for the Humane Society of the United States. He never imagined a career there, but he stayed for 10 years. In his work helping communities to live with wildlife and free-roaming horses, he became interested in the science of contraceptives and came to Tufts.
Rutberg talked about other wildlife where contraceptives might be useful in managing populations. There has been work on coyotes and foxes, but, he said, the problem is you have to catch them. Also, being territorial, they tend to control their own populations. Oral contraceptives can manage the increasing numbers of intrusive birds, especially pigeons and geese. He said free-roaming pigs, which reproduce rapidly and are very destructive, are all over the South. Bears are becoming the most common nuisance, and Rutberg said he is mindful of the “what ifs” of an overpopulation of bears. They are increasingly common in Western Massachusetts, especially in the Connecticut River Valley, and they have been slowly spreading east. He confirmed what many Harvard homeowners already know: the town is well within their range now.
The challenges to wildlife contraceptive use really are now more regulatory, political, and logistic than scientific, Rutberg said. “It would be nice if we could leave everything in nature as it is, but that’s not possible in this world.”