Thursday, December 11, 2008

Black-footed Ferret Reintroduction Celebrates 10 Years in Aubrey Valley

September/October 2006 Wildlife Views article by Angie McIntire,

It’s 2 a.m., Oct. 28, 2001.

Filled with nervous excitement, I dial Bill Van Pelt’s number. Bill, who manages the Arizona Game and Fish Department’s nongame birds and mammals program, will want to hear this news.

Bill’s wife, Lola, answers. She is trying her best to sound awake and composed, but I hear an edge of concern in her voice.

“Lola? It’s Angie. Nothing is wrong. I’m sorry to call so late. Can I talk to Bill for a second?”

I hear shuffling as the phone is passed, then Bill’s groggy voice. In one breath I blurt out, “Bill, it’s Angie. I’m at the field station and you’ll never guess what I’m about to do. I have a wild-born male black-footed ferret, and I’m getting ready to implant a transponder. We have traps set out on three or four others. I think it’s a dispersing litter, and one could be the dam. It seemed like there were ferrets everywhere. It was incredible. I was running from one burrow to the next, lugging a 15-pound battery and the PIT-tag reader. It was like a dream.”

In his best awakened-in-the-middle-of-the-night voice, Bill manages to say, “Wow, that’s great.”

Back from the Brink

I had rehearsed for that night for more than five years, practicing my “Guess what I found” speech to keep myself awake as I drove hour after hour with a million-candlepower spotlight hanging out the vehicle window. Depending on strong coffee and the belief that it could happen, I scanned my light back and forth across the large valley expanse, searching for a pair of green eyes peering from a hole in the ground, hoping someday I would find a wild-born litter to warrant that late-night call.

The miraculous story of the return of the black-footed ferret is well-known in conservation circles. They were thought to be extinct only 25 years ago. But everything changed on Sept. 25, 1981 when a ranch dog in Wyoming killed the first ferret to be seen since 1979, proving that ferrets still existed. The discovery launched a recovery effort that is still underway.

In September 1996, with the release of 35 black-footed ferrets, Arizona became the fourth state to reintroduce these animals to the wild. While this date marks the milestone when we opened cage doors, the effort truly began some 13 years before, when the Arizona Game and Fish Department’s habitat specialist in Flagstaff, Glen Dickens, posed a question to the department’s nongame branch chief, Terry Johnson.

“Terry,” asked Dickens, “Are searching for ferrets and looking for sites where they could be reintroduced worthy pursuits for the department?”

Johnson’s answer was, “Yes.”

Since then, field crew members, interns, wildlife managers, department biologists and hundreds of volunteers have contributed thousands of hours and spent sleepless nights conducting spotlight surveys, hoping their efforts would pay off. Ask anyone who has been involved with the black-footed ferret reintroduction, “When did this begin for you?” and you get an answer full of passion.

Creativity Breeds Success

When Arizona joined the national effort to reintroduce ferrets, it pioneered several release strategies to forge a unique path to success. The first of these was the use of large outdoor acclimation pens. This was a new release strategy, allowing animals to acclimate to their surroundings and practice hunting for food within an enclosed quarter-acre pen.

Because of the extended time each ferret spent in its pen area, we imagined that once released, our ferrets would disperse slowly after living for some time in burrows adjacent to the pens. For release, we literally cut small holes in each pen section and inserted long flexible PVC tubing to lead the ferrets out to nearby burrows.

The animals left their pens, but most were not seen again. Although we occasionally found a ferret living in the wild after its release, we were hard-pressed to document long-term survival from pen enrichment alone in those early years.

Competition was fierce among reintroduction sites for releasable ferret kits from captive breeding facilities. So we wondered: What if we bred our own ferrets? From that idea, we blazed another trail, becoming the first reintroduction site to breed black-footed ferrets in our outdoor preconditioning pens. After all, wouldn’t ferrets that had never been in zoo captivity be better equipped to survive in the wild?

The first year we attempted to breed ferrets (1997) we maintained a hands-off policy, just putting male and female ferrets together to let nature take its course. That year, we could not document whether any litters had been born. We attempted breeding trials again in 1998, changing our methods to include visual inspections and chemicals and laboratory work to help us make better decisions. We were rewarded with 26 kits, numbers similar to those at captive-breeding facilities.

As any wildlife biologist can tell you, funny things happen in the field. The very first litter born in our pens was a mystery. We never actually paired that first female with a male, yet she became pregnant. We assume the male ferret (named Houdini, if you can believe it), who escaped from the adjacent pen within days of her pregnancy window, was the culprit. Somehow, he snuck into and out of her pen undetected (not an easy task, since the pens were strung with electric wires).

In 1999, we produced even more kits. Although our pen-breeding effort was successful enough to be replicated by other reintroduction sites, it was not materializing into long-term survival or reproduction in the wild. A nocturnal animal that lives underground is relatively difficult to track, and we surely missed a few in our monitoring efforts. But certainly, there was no smoking gun to show us we were on track. After thousands of survey hours, we still didn’t have any clear indication a population was taking hold, let alone building. We wondered if what we were doing was working.

Again we tried something that had never been done at another site: We released animals in the spring rather than the fall. Because ferret kits are born in May and June and gain their independence around October, this is when they are naturally available from captive-breeding facilities for release. Instead of releasing them in the fall, we decided to hold animals in the preconditioning pens through the winter, thinking that a release in the spring would provide an easier transition from captivity to wild. The air would be warmer and more food would be available.

In addition, we hedged our bets by pairing male and female ferrets as we had in our captive-breeding days, hoping that some females would be pregnant for their release. If females were pregnant, they would whelp in the wild. In case they weren’t, we released males in proximity.

Return of the Ferrets

After the spring release in 2001, the momentum began to turn, finally warranting that middle-of-the-night phone call. Since then, the number of wild-born ferrets trapped for identification each year has been on the rise, with 29 trapped and released in 2005. The number of ferrets seen during spotlighting events grows each year as well, with more than 100 sightings in the spring 2006 survey.

In his May 1996 “Arizona Wildlife Views” article, “Green Eyes Glowing in the Night,” Terry Johnson asked, “Will this reintroduction work?” He foresaw that “Countless factors may intervene from a lack of releasable animals to an inability of captive-reared ferrets to adapt to the wild.”

Johnson was right. Those and other factors have intervened. But our will to succeed has been strong, and 10 years into the project I know Bill sleeps soundly. After all, the field team is now far too busy counting wild ferrets to make any late-night phone calls.