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Posted on 11/22/2001 4:50:47 AM PST by Bowana

The Deer Wars Part 2: Mad Science

Bio-Bullets and darts filled with an experimental drug are being used to sterilize deer. then there are the other options, such as splicing a sterilization agent onto a virus and setting it loose. an update on deer birth control.

The experiment is bold and groundbreaking. Years have already been invested and budgets stretch well into six figures. Half a dozen scientists are taking part along with dozens of volunteers. But it's all going to be worth it, says the Humane Society of the United States (HSUS), because in the end the research will prove to the world that it doesn't take hunters to control deer populations.

The Humane Society is a national organization with a staff of 250 and a membership of about 7 million. Its literature describes lethal controls for deer as "irresponsible," so the group's agenda is clear. But can this wealthy nonprofit organization find a way to control deer without using hunters?

To achieve this goal, HSUS needs to prove it can control a wild, free-roaming deer population with immunocontraception (birth control). So its first step was to find a test area it could control. It settled on Fire Island, a 32-mile-long and half-mile-wide barrier island near the south shore of Long Island, New York. Fire Island has more than 200 deer per square mile‹so many whitetails that the bird life is nearly gone due to overbrowsing. It's a test model where most of the island's 4,000 homeowners are affluent New Yorkers who use their homes as getaways. The National Park Service, which owns one third of the island, is even letting the scientists use parklands‹HSUS couldn't have asked for more.

Now it needed to prove that its sterilization drug could handle the job.

The Miracle Drug The Humane Society is using a drug called Porcine Zona Pellucida (PZP), a natural protein that allows boar sperm to attach to a sow's ova. When injected into females of other mammal species, PZP elicits antibodies against that animal's sperm-recognition protein, thereby stopping sperm from entering the egg.

The Humane Society got control of the drug when Dr. J.F. Kirkpatrick, a scientist at ZooMontana's Science and Conservation Center in Billings, Mont. (the center is partially funded by HSUS), signed his Investigational New Animal Drug Document (INAD) for PZP over to HSUS. This document, which is issued by the Food and Drug Administration (FDA), is important, because without it, no person or organization can use the drug‹unless, of course, HSUS signs on.

Dr. Kirkpatrick's employer, Zoo-Montana, is the only major producer of PZP. Its freezers are stuffed with pig ovaries from Iowa's slaughterhouses, and its technicians work year-round drawing PZP from sows' eggs.

But PZP is not perfect. It seemed like a miracle drug at first, because it will sterilize any mammal‹human, goat, you name it‹but PZP's equal-opportunity nature makes it dangerous. You can't put it on baits so that deer will ingest it orally, because other animals might also ingest the drug. Scientists are not even sure whether humans would be affected if they were to consume the flesh of a PZP-treated deer. Because of this, Dr. J. Russell Mason, a biologist with the USDA's National Wildlife Research Center in Logan, Utah, argues, "What pharmaceutical company would make such a lawsuit-luring monster?" This is the main reason why PZP continues to be listed by the FDA as an "experimental" drug.

Still, Dr. Allen Rutburg, a professor at Tufts University and a member of HSUS's technical staff, says, "We do plan to gain FDA approval for the drug. One day we hope the drug will be used widely across the country instead of hunting."

With this goal in mind, the researchers on Fire Island moved ahead to prove that PZP could be used to curb wild, free-roaming deer populations. What they needed were numbers to support their hypothesis. The methodology, technological advances and FDA approval would, they hoped, come along the way.

The Study Excitement was high on Fire Island when Dr. Kirkpatrick arrived in 1993 to help start the study. He found himself rubbing shoulders with Calvin Klein, Geraldine Ferraro and other rich and famous Fire Island homeowners who were footing much of the bill for the project. Several members of HSUS, along with employees from the Fire Island National Seashore (FINS), darted 74 deer. However, it wasn't as easy as they'd thought.

They started out using Pneu-Dart guns loaded to shoot darts filled with PZP. The problem with these guns is that they have a trajectory like a rainbow. But part of the goal is to find and fix the problems before the project's end, which is still indeterminate, so HSUS started exploring other options. Next, researchers tried blowguns, which are easier to use and much cheaper than dart guns. But their trajectory is even worse than a dart gun's. Finally, they gave bio-bullets a try. The concept here is simple: An air gun is used to send a bio-bullet (a time- release capsule filled with PZP) into the muscle in the hindquarters of a deer. The capsule is absorbed into the deer's system over several months, slowly releasing the drug. This is a good idea because PZP-loaded darts don't always sterilize a deer. Sometimes a dart will sterilize a deer for several years and sometimes it won't‹a fact that forced HSUS to dart deer twice a year.

Currently, however, according to H. Brian Underwood, research wildlife ecologist with the Biological Resources Division of the U.S. Geological Survey, no one is making bio-bullets, because there are too many problems with them. For example, finding the correct amount of air pressure is difficult: Too much and they'll kill the deer, too little and they'll simply bounce off. This is doubly difficult because bio-bullets are so light that they lose velocity quickly, and there's just no telling where a deer will show up, which makes it hard to choose the correct air pressure. (The Humane Society has not given up on bio-bullets, however. It is now trying a different approach. Researchers are sticking a small capsule on the tips of darts and then shooting deer with them. This method has not yet proven successful.) One thing that HSUS has found is that as promising as baiting and darting deer sounds, it isn't practical. A digestible, orally administered drug would be less time consuming. The Humane Society considered RU486 (the abortion pill recently approved in the U.S.), but the social resistance to its use has kept HSUS from trying it.

According to Dr. Michael Holland, an Australian biologist now working with the USDA Predator Ecology Center in Logan, Utah, another option may be to isolate the gene in PZP that is sterilizing the animals and purify it. DNA technology could conceivably be used to clone that gene. It then would be theoretically possible to make a commercial vaccine that is species specific from the cloned gene. The vaccine could be put into baits or dropped from planes, much like rabies vaccines are scattered for coyotes. Dr. Holland says, "It would take millions of dollars and several years of work. And then you'd still have to start the long drug-approval process. But it could be done." Things begin to get pretty sci-fi after that. For example, there are immunocontraceptives being developed in many countries for many species (humans included) that could one day be used on deer. Vaccines are being worked on that inhibit brain reproductive hormones, pituitary hormones and steroid reproductive hormones. But the award for the most innovative approach goes to Australia, where, according to Dr. Holland, scientists spliced a gene for a contraceptive antigen to a virus. The virus was then set loose. In the wild it passed from rabbit to rabbit, sterilizing them as it went. Now, of course, come the "what ifs?" Such as, what if it mutates and humans catch it? Dr. Rutburg said this scares HSUS too much to try.

The Discoveries Ecologist Brian Underwood of the USGS says, "I've found out a few things they're [HSUS] not going to like. There are side effects to PZP. For example, in a treated herd the rut lasts seven months a year as does come into estrus again and again. But on the upside, PZP-treated does tend to be larger and healthier because they don't have fawns to feed. As for the bucks, the only problem is that the males may wear themselves down to the point that a tough winter will kill them."

The costs for the project are as difficult to tally as the facts of this study are, so it is unclear how cost-effective immunocontraception is.

When asked about Fire Island whitetail population numbers, Underwood said, "There are five separate populations being darted on the island. Of these, one appears to be going down. Though this is a failure if you look at it as a population-reduction study, it has been a success from a research standpoint‹we know much more now about PZP than we did."

Dr. Mason is more decisive. He says, "In eight years, with a controlled study and tons of volunteers working with a deer herd that was virtually all known on a first-name basis, they [HSUS] couldn't pull it off."

But while it is clear that HSUS does not yet have the technology to control a wild, free-roaming deer population, Dr. Kirkpatrick, who is a hunter, argues that, "State-sponsored hunts in the suburbs can do more to fuel anti-hunting sentiment than all the rhetoric from anti-hunting groups combined; as a result, hunters should stay out of the urban deer struggle. The Humane Society will find a nonlethal solution."

Dr. Mason sees it differently. He says, "Hunters are the most effective management tool for controlling whitetail populations. Despite what HSUS says, right now deer contraception is up in the clouds somewhere."

Dr. Anthony J. DeNicola, president of White Buffalo, a nonprofit organization that specializes in sharpshooting whitetails (see Deer Wars, Part I, "A Beleaguered Mayor Meets the Deer Slayer," October), summed up the state of affairs this way: "HSUS is an agenda group‹they'll do what it takes to accomplish their agenda. That said, they're also the most reasonable organization of their kind. What HSUS is good at is dealing with the press and with suburbanites, which is exactly where hunters typically fail. But if hunters could get together behind a scientifically sound national organization that would hook communities up with responsible hunters, then I would be getting a lot less business."

Next month, in Part III, you'll meet such a sportsmen's group.

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