OUT: Sunday Column October 05, 2008

Anti-fertility drugs finding some success in animal control

Wildlife managers always have turned to hunters to help control game populations.

It’s surely not the most effective system and you’ll find arguments pro and con about hunting’s efficacy, from the disappearance of the passenger pigeon to the semi-control the Division of Wildlife struggles to maintain over elk herds.

However, there are some areas, notably our national parks where hunting isn’t allowed and in those urban/wildlands interfaces where hunting is awkward at best, where hunting is not part of the population control equation.

And in spite of arguments and lawsuits filed by some conservation groups seeking the restoration of wolves into the state, that management tool needs more than a massive federal bailout to enliven its chances.

One of the control methods being considered, however, is using fertility drugs to control reproduction.

Once thought the realm of mad scientists and animal rightists, using anti-fertility drugs for animal control is being studied around the world. Research on grey kangaroos in Australia, brushtail opossums in New Zealand, rats in Asian rice fields, and more indicate success using drugs to
control reproduction.

Researchers at the University of Melbourne reported that “both immunological and endocrinal approaches have shown dramatic progress in the last five years, suggesting that long-term broad-scale fertility control is now within reach.”

Colorado wildlife managers have shied away from fertility control for several reasons, including the cost of capturing animals and administering the drugs.

However, with mounting evidence of the newer drugs’ serviceability and the news the National Park Service is about to start tampering with nature’s cycles, the Division of Wildlife has decided it’s time to peek inside this particular Pandora’s box.

“There’s been some pretty good research in Colorado and elsewhere that some of these drugs work,” said Rick Kahn, state terrestrial program manager for the DOW. “We’re just asking the (Colorado Wildlife Commission) to put some sideboards on the issue (because) right now there is some concern some people or a city or something could use the stuff with no degree of control.”

In January, Rocky Mountain National Park will start testing a multi-year anti-fertility drug on elk as part of the park’s Elk and Vegetation Management Plan. Up to 60 cow elk a year will be treated with GonaCon, a hormone that suspends fertility for up to four years in tests on captive deer.

Thursday, Kahn urged the state wildlife commissioners to start thinking about a policy aimed at keeping the DOW in the lead of this situation.

“Our desire isn’t to promote it but to control it,” Kahn said. “We want to make sure that if it’s done, we can make sure it’s done in an appropriate manner.”

Kahn told the commission that “there are places up and down the Front Range where traditional methods of harvest are not practicable.”

He wasn’t talking only about burgeoning herds of mule and white-tailed deer in urban settings but also such species as prairie dogs, which are protected from hunting.

In some places, drug-induced population control might be the most acceptable solution.

“I would think this is not an attempt to replace hunting seasons with wildlife fertility control procedures,” emphasized commissioner Jeff Crawford.

Kahn responded that any policy presented to the commission would put hunting first.

“This is an attempt to reaffirm that traditional methods where possible should be used,” he said.

Anti-fertility drugs “would only be used in rare situations.”

“But without a policy or regulation we are going to be lacking” should someone seek permission to use these drugs, Kahn said.

Understandably, hunting groups are in the forefront of the opposition to using fertility drugs. In 2003, Jay Kirkpatrick of the Science and Conservation Center at ZooMontana in Billings noted, “Despite impressive advances in the application of wildlife fertility control, this management tool remains underused because of opposing political forces.”

Another factor is the residual effects of these drugs.

Because it’s not known how long it takes for the drug to clear an elk’s system, hunters who kill an elk in areas adjacent to Rocky Mountain National Park “may find a tag on the elk informing them the animal should not be consumed,” said a park news release.

Which poses an interesting question: Does killing an elk wearing a “don’t eat me” tag count against your license?

The commission decided not to act and directed the DOW staff to draft preliminary regulations for a later commission meeting.


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