As I See It: Science tackles deer problem

Jan. 10, 2016 - Worcester, Mass. - Since our research group darted the first free-roaming deer with contraceptives on Fire Island, New York, in 1993, we have been told again and again that deer contraception cannot work.

But in those years, the criticisms shifted: Our vaccine cannot prevent free-roaming does from having fawns; it can work on individual deer, but cannot control deer populations; it can control deer populations, but only on islands; it takes too long; it taints the meat; it’s too expensive. And on and on.

The criticisms have had to change as the science proved them wrong. We published data showing that our contraceptive vaccine, porcine zona pellucida (PZP), prevented free-roaming does from having fawns (1997); that we could reduce free-roaming deer populations (2002); and that, at least in some environments, we could do so reasonably quickly (2013). Because it’s a natural protein vaccine, the contraceptive does not taint the meat; it’s destroyed in digestion. But confusion with steroid contraceptives has allowed the tainted meat argument to sit on the shelves long past its expiration date.

In his column of Dec. 17 (“Contraception won't shrink deer population in Blue Hills”), Mark Blazis adds his own “can’t” to the parade.

According to Mr. Blazis' column, the 50 percent deer-population reduction we accomplished in five years at our study site at Fripp Island, South Carolina, took too long and didn’t get the job done. He quotes a South Carolina deer-management official and I'm surprised to hear the conclusions drawn. We did get the job done, in a reasonable amount of time: Five years is also the time that the state Department of Conservation and Recreation targets to accomplish a 50 percent deer-population reduction at Blue Hills using a 3-5 day shotgun hunt.

The difference is that DCR hasn’t actually done it yet.

The deer population living on the control site next to Fripp Island, the ironically named Hunting Island (no hunting is allowed), remained stable throughout our study. The Fripp population was still declining when South Carolina’s Department of Natural Resources chose not to renew our research permit.

As Mr. Blazis noted, the costs of the study ran into the six figures. But that’s a total, over five years, including the costs of population surveys, pregnancy tests and all the other necessities of research. Contraception projects will be pricier in some areas, cheaper in others. Costs are expected to decline as the technology improves.

Currently, there are two different versions of the PZP vaccine. One, very similar to the vaccine used in 1993, is cheap to make but requires annual boosters for at least a few years to remain effective. The second version is more expensive to make, but the first treatment lasts two to three years, and boosters may last for three years or longer.

Would our contraceptive achieve Blue Hills’ deer-population reduction goals? Mr. Blazis is right; given the current state of the technology, probably not. With better technology and more field experience, maybe.

But after 20-some years, I don’t expect that the arrival of a cheaper, more effective, longer-lasting deer contraceptive will quiet the criticisms from the outdoor press and their hunting constituents.

Quite the opposite. Their concern is not that contraception won’t work, but that it will.

Dr. Allen Rutberg, DVM, is director of the Center for Animals and Public Policy, Cummings School of Veterinary Medicine at Tufts University. A behavioral ecologist and urban wildlife specialist, he focuses primarily on resolving conflicts with white-tailed deer and other wildlife.

Originally published Jan. 10, 2016, in the Worcester Telegram.

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