Deer Contraception: Birth control is not the solution some would have the public believe. (Expeditions).
Hardly, says Dr. Robert Warren, a professor of wildlife ecology and management at the University of Georgia. In fact, there has been little progress in terms of an effective and inexpensive method to treat wild, free-ranging deer herds since the issue came to light at the first conference on wildlife contraception in 1987. Some methods have indeed worked on captive deer herds and semi-tame populations of free-ranging horses, but results on wild animals have been marginal at best. The Humane Society of the United Stares--one of the strongest and most vocal opponents of hunting both as sport and as population control mechanism--has been working to find a viable, long-term method of birth control for deer for more than 10 years.
Two methods--surgical sterilization and synthetic steroid hormone implants--involve invasive procedures that are both costly and time consuming, two factors that will likely keep them from becoming viable options. Ironically, the best alternative that is being promoted by the HSUS involves the use of PZP, a protein that is found in pig ovaries-pig ovaries that are collected from slaughterhouses. (The HSUS, says it is working to develop a synthetic form of PZP.)
The problem with this method-or any method, adds Dr. Warren-is that it is virtually impossible to administer birth control devices to wild, free-ranging deer and still keep track of the does that have been immunized.
"If it isn't a permanent method such as surgical sterilization, then deer need to be given a dosage of PZP twice the first year and about once a year after that to maintain infertility. There simply is no way to keep track of all the deer in a free-ranging herd," notes Warren, who has been studying this issue since 1985.
Equally difficult is the actual vaccination of individual deer, which must be given a shot with a dart gun or with a "bio-bullet" shot from a specialized gun with an effective range of less than 30 yards. Bio-bullets, which consist of compressed cellulose, chemicals and the vaccine itself, need to be shot into a deer's hindquarter to a depth of about one inch.
An immunocontraceptive study took place on an isolated population of deer in New York between 1993 and 1998. Each year, between 70 and 200 does out of a total population of about 300 were treated with PZP. Fawning rates decreased by about 90 percent, but the overall size of the deer herd did not decrease, according to Warren.
"Computer-generated models predict that it will take between five and 20 years for deer numbers to decrease, but at least 70 percent of a herd's population of does must be treated every year," he added.
Perhaps even mote disturbing is the overall effect of altering an animal's reproductive behavior. Remember the commercial slogan "It's not nice to fool Mother Nature"? Warren says whitetail does that have been treated with PZP may come into heat monthly as late as April or May. Biologists are clearly concerned with the idea of tampering with natural reproductive cycles in wild animals.
"The long-term effects of multiple heat cycles aren't known. We do know that fawns born late in the spring or into the summer may not have enough time to build up necessary fat reserves before winter, which could result in a high winter kill among fawns in some regions," he says.
Another major hurdle to deer immunocontraception is that of safety-for both wildlife and humans. So far, the Food and Drug Administration has nor approved the use of PZP for deer that might be consumed by hunters.
The other alternative, synthetic steroid hormones, is approved for use in domestic animals, but biologists are concerned about the effects on predators and scavengers that consume deer which have been treated with hormones.
Even if the HSUS or any other antihunting group finds a way to control the birth rate among wild populations of whitetails, they still have to get it past state wildlife, agencies and the general public-and that could prove particularly problematic if taxpayers are asked to fund such an expensive, ongoing operation. One study in Ohio reportedly cost $1,100 per treated doe, according to Warren.
The HSUS is researching longer-lasting methods of contraception, but if it manages to develop something that can be administered only once, workers would still have to find untreated deer, get close enough to vaccinate them and then mark the animals so valuable time and money aren't spent treating the same animals repeatedly. Every hunter who has spent time in the deer woods knows exactly how hard such a job would be.