Return of the Fisher

The football game wasn't going my way; so I decided to get physical and pull 3 cameras that had been soaking in the rain.

I headed up Skyway, parked the truck, mountain-biked a couple miles, surmounted a blow-down across the trail, and fell on my butt on the way down the ravine.

The first camera was dry, but three bears had bumped it off target during a  bumble-fest of scent-rubbing.

The news from the second camera was good and bad.

The bad news was the water in the case; it shorted a circuit and shuttered pictures like a machine gun.

The good news was a photo of a radio-collared fisher.

And the camera in the next ravine had more pictures of the same critter.

Discovering the scent lure

A good thing has happened.

California Department of Fish and Wildlife, the US Fish and Wildlife Service, and Sierra Pacific Industries (SPI) have joined forces to restore the fisher to the northern Sierra Nevada.

This radio-collared animal might be one of 40 fishers that were translocated from the northwest corner of the state to SPI land near Stirling City.

But it could also be one of the 48 offspring born to the colonizers over the past three years.

The historical occurrence of fisher in California has been a puzzle.

California's great academic naturalist, Joseph Grinnell, assumed fishers ranged throughout the Sierra Nevada.

Since Grinnell's time however, fishers were found to be missing from a 420 km section of the northern Sierra Nevada.

This "dead zone" is an enigma, because the habitat seems to have everything a fisher needs . . . a fisher-friendly climate, lots of trees, water, cover, squirrels, and maybe even a few porcupine.

Biologists have assumed that logging and trapping divided the population, leaving one in the southern Sierra Nevada and the other in the Trinity Alps and coastal mountains of NW California.


A recent study based on DNA from museum specimens and living animals tells a different story.

California's fishers became divided populations about 1000 years ago.

In other words, we can't blame the fisher gap on the Spanish colonization of California and the gold-lust-mayhem of the 49ers.

Fur trapping and intensive logging in the early 1900s, however, caused the continued decline of fishers across North America, and in 1946 California was the last fisher range state to enact protective legislation.

The two populations are now genetically different, which raises questions about their conservation.

Like, should we connect the northern and southern populations, and risk genetic pollution of their gene pools?

Or should we colonize the gap with fishers and brace the population against future environmental unknowns?

I rather like the idea of filling the fisher gap. California's just an experiment, isn't it?

Having a few more fishers around makes the place more interesting.


References

Grinnell, J. 1913. A distributional list of the mammals of California. Proceedings of the California Academy of Sciences, 3:265-390


Grinnell J, Dixon JS, Linsdale JM (1937) Fur-bearing mammals of California: their natural history, systematic status, and relations to man. University of California Press, Berkeley. 375 p.

Powell, RA. 1993. The Fisher, life history, ecology and behavior. University of Minnesota Press, Minneapolis. 237 pp.


Powell, RA,  RC Swiers, AN Facka, S Matthews, and D Clifford. 2013.  Reintroduction of Fishers into the Northern Sierra Nevada of California,  Annual Report for 2013 For the period of October 2009 to December 2013, 35 pp. 

Tucker, JM, MK Schwartz, RL Truex, KL Pilgrim, and FW Allendorf. 2014. Historical and Contemporary DNA Indicate Fisher Decline and Isolation Occurred Prior to the European Settlement of California. PLOS One 7(12):1-13
http://yubanet.com/regional/Population-declines-isolation-of-fisher-in-California-pre-date-European-settlement.php#.VJECaShpCc8

Gabriel, MW,  et al. 2014.  Anticoagulant Rodenticides on our Public and Community Lands: Spatial Distribution of Exposure and Poisoning of a Rare Forest Carnivore. PLOS One 7(7): e40163. doi:10.1371/journal.pone.0040163

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0040163

Zielinski WJ, Kucera TE, Barrett RH (1995) Current distribution of the fisher,

Martes pennanti, in California. Calif Fish Game 81: 104–112.

Adventures with Robobadger

Robobadger was a marriage of taxidermy and a high tech toy. His first life ended abruptly on state route 287 near Laramie. The next day his ice-packed remains arrived at the National Museum of Natural History in Washington D.C. There a taxidermist worked his timeless magic, and a month later Robobadger began his second life on wheels. Robo looked menacing even with a remote-control toy jeep embedded in his solar plexus.

Robobadger became a kind of drill sergeant in Brian Miller's boot camp for Siberian ferrets. Brian was a Smithsonian Postdoctoral Fellow at the National Zoo. Robo, a stuffed great horned owl, and Brian's dog Rosa were joined in a common purpose to scare the bejeepers out of the ferrets. It would also teach us how ferrets develop a healthy fear of predators.




Boot camp also taught the ferrets how to find and dispatch food such as prairie dogs, but that had little to do with Robobadger. Zoo biologists have long known that animals raised in captivity are wusses in the wilderness. Eating a nutritious meat mix isn't the same as dispatching a prairie dog face-to-face in its burrow, or dodging coyotes.

Boot camp at the zoo's Conservation & Research Center was preparation for the Siberian ferrets' experimental release on the high plains of Wyoming and Colorado. The small captive population of black-footed ferrets was too precious to use for an experiment, but the Endangered Species Act makes provision for experimental introductions with related or surrogate species. If captive born black-footed ferrets were to thrive in the promised land of reintroduction they needed serious preparation. The surrogates would lead the way.

Being a reintroduction surrogate is a little like being an astronaut. Both undergo rigorous training in order to explore strange new places, and the goal is survival. The biggest difference is that a veterinarian doesn’t neuter astronauts before the mission. It was necessary with the ferrets, because reproduction on the new frontier was not an activity condoned by the US Government. As you may have guessed, Siberian ferrets are considered aliens in the US.

Boot camp had several phases. Robobadger and the stuffed owl were players in an experiment to see whether predator avoidance was hard-wired in the genes or coached in the school-of-hard-knocks. Their advantage over a live predator was predictability.

Brian also wanted to see how these behaviors developed in young ferrets. To see if there were critical learning periods he designed experiments in slices of developmental time. He ran the experiments on three groups of young Siberian ferrets at two-, three-, and four months of age.

The experiments went like this. On day 1 a young Siberian ferret encountered Robo resting benignly in the corner of the 10 x 10 foot arena. On day 2 the ferret found itself zapped with rubber bands while being pursued relentlessly by a belligerent Robo. Operating the joystick, shooting the rubber band gun and taking data kept Brian and his bevy of assistants quite busy at mission control.

I should explain that the original plan was to fit the ferrets with shock collars used in training dogs, but the Zoo's Animal Care and Use Committee nixed the plan, and Brian settled for a rubber band "six-shooter".

The criterion of success was the time it took for the ferrets to disappear down the burrow to safety. The day after the chase, he put the same ferret back in the arena with Robo sitting quietly in the corner. He again measured the time the ferret took to dive into the burrow and compared that to the time of escape before Robobadger chased the ferret. He repeated the experiment using the stuffed owl.

The results were clear. Two-month-old Siberian ferrets were as helpless as gum drops, but 3- and 4-month-old ferrets had a healthy fear response, and it was faster at four months than at three.

What's more, it took only one aversive experience with Robo or the owl to improve the innate response. In other words, the ferrets had a genetic memory of predators, but a good scare improved the survival response, which was simply to beat a hasty retreat down the burrow.

Following these experiments in captivity, the Siberian ferrets were released into the wild. Alas, the experiments with Robobadger and the owl didn't affect survival in the wild. Even though the young ferrets did the right thing after generations in captivity, they didn't do it well enough when faced with wily coyote.

Brian retired Robobadger and the next year stepped the boot camp up a level. He introduced prairie dogs to a dirt-floored but escape-proof barn, and when they settled down he introduced young Siberian ferrets. It was a pre-release conditioning arena where ferrets could live in natural prairie dog burrows, secure their own food and occasionally deal with Rosa the Labrador's intrusions.

This conditioning did indeed improve the Siberian ferrets' survival. The method was tested next on black-footed ferrets released in Montana, and survival improved from 2% to 20%. The US Fish & Wildlife Service made it mandatory for all captive-raised black-footed ferrets scheduled for release in the wild.

Meanwhile, word of Robobadger spread to Washington and beyond, and then one Sunday morning in 1989 we read about Robobadger in Dave Barry's column in the Washington Post.

Yes, it was amusing, but we were sweating bullets. A colleague of ours had just won the dreaded a Golden Fleece Award in connection with another reintroduction project. If Senator Proxmire found out about Robo Brian and the National Zoo could also be honored with a Golden Fleece Award. It was recognition we were NOT seeking. (Actually our fears were unwarranted, as the research was not federally funded.)

What to do? How about sending Dave Barry an autographed photo of Robo and letter? I suggested. If he likes us, maybe he'll come to our defense if we do get a Golden Fleece.

The deed was done. "Dear Dave, That was a great article you wrote about me . . . etc.
Sincerely, (signed) Robobadger (with pawprint)"

A couple weeks passed and then a book arrive din the mail. It was "How to Claw Your Way to the Top", dedicated by Dave Barry "To Robo, who obviously needs no help from me."

If you have ever seen a badger's claws, you will instantly get Dave's inference.

You can read the full story in Prairie Night. The book is out-of-print, but used copies are still available. Brian is also planning an updated second edition.

[Thanks to Brian for refreshing my memory about some of the details and to Dean Biggins for the photo at the top of the page. Dean is seen in my B&W photo standing to the right of Brian at the edge of the ferret arena.]

References

Miller, B. 1996. Prairie night. Washington DC, Smithsonian Institution Press

1991. Development of survival skills in captive-raised Siberian
polecats (Mustela eversmanni) I: Locating prey. Miller, B., D. Biggins, C.
Wemmer, R. Powell, L. Hanebury, D. Horn, and A. Vargas. Journal of
Ethology 8: 89-94.

1991. Development of survival skills in captive-raised Siberian
polecats (Mustela eversmanni) II: Predator avoidance. Miller, B., D.
Biggins, C. Wemmer, R. Powell, L. Calvo, T. Wharton. Journal of Ethology 8:
95-104.

Papers evaluating pre-release experience of black-footed ferret
survival:

1998. The effect of rearing methods on survival of reintroduced
black-footed ferrets. Biggins, D.E., Godbey, J.L., Hanebury, L.R., Luce, B..
Marinari, P.E., Machett, M.R., and Vargas, A. Journal of Wildlife
Management 62: 643-653.

1999. Influence of pre-release experience on reintroduced black-footed
ferrets (Mustela nigripes). Biggins, D.E., Vargas, A., Godbey, J.L.,
and Anderson, S.H. Biological Conservation 89: 121-129