Wild Again. David S. Jachowski
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young kits in Montana.
We followed the husbandry protocol developed by the ferret recovery program on the basis of its success with the last eighteen individuals from Meeteetse. A sort of how-to guide for ferret keeping, this protocol had evolved over time with guidance from the Wyoming Game and Fish Department, the Captive Breeding Specialist Group of the IUCN (International Union for Conservation of Nature), and the American Zoo and Aquarium Association, and with hands-on expertise of many devoted biologists over the years at Sybille Canyon, Wyoming. By 1996, the U.S. Fish and Wildlife Service had assumed responsibility for captive breeding from the Wyoming Game and Fish Department, and the person to contact about any captive breeding question was Paul Marinari. Paul would be the first to deny the label of “Mr. Ferret,” placing credit with the teams and individuals that preceded him, but he more than any other person oversaw the quick acceleration in ferret-breeding success, and developed a smooth and effective operation that produced an annual flow of 150–200 kits.
When I first met Paul in 2002, he was single and lived alone in Sybille Canyon with the ferrets while the technicians that worked with him commuted the two-hour round trip up from Laramie each day. Upon first shaking his hand, I noticed that he had the sharp personality and watchful eye needed to ensure the conditions and care for such a sensitive animal. Originally from Philadelphia, Paul completed his master of science degree from the University of Wyoming by studying ferret behavior in South Dakota and evaluating the detectability of ferrets via night spotlighting surveys. Like a field biologist, to succeed at his job of overseeing captive breeding of black-footed ferrets, Paul dedicated and set the rhythms of his life to ferrets. He lived in a small home on the captive breeding site because caring for ferrets in captivity was not a 9-to-5 job. It required continuous attention and ability to respond to emergencies at all hours of the day and night. Ferrets had to be monitored and fed, and their cages had to be cleaned daily throughout the year. In springtime, monitoring of females was required to determine when they were in estrus to pair them with mates. Then, forty-five days later, they had to be monitored for births and the status of litters. In the summer, there was a need for monitoring and caretaking of vulnerable kits and their mothers. Then, in late summer and fall, kits were preconditioned and transported for release on reintroduction sites from Mexico to northern Montana. After the kits were shipped out to sites by October or November, planning for next year commenced as pedigrees were assessed and potential mate pairings were mapped out for February and March of the coming year based on a formula that aimed to maintain the greatest possible genetic diversity of the captive population. There was little time for vacation, and even less time for a personal life.
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To rear the rarest mammal in the world required specially designed equipment. In Malta we built plywood nest boxes to Paul’s specifications for female birthing. A nest box was a small, sturdy, two-chambered box with a four-inch entry door from the top that could be locked with a latch. At the bottom of the box, a hole was drilled and four-inch-diameter black corrugated tubing was tightly connected that led to a larger plywood box with a Plexiglas front and screen top to resemble above ground exposure. All boxes were kept sterile and painted bright white. Outside, sixteen adjacent pens, each thirty-two feet long by thirty-two feet wide, were erected directly into and onto the prairie. Prairie dogs captured on local cattle ranches were brought in by the hundreds, quarantined, killed, gutted, organized into individual plastic bags, and frozen for a year’s worth of ferret food. Valerie had already established a colony of more than one hundred hamsters housed in metal bins in a nearby garage bay that would be used to feed young kits and train them to kill live animals. This was a gentle introduction to predation, as the small puffball hamsters were less likely to hurt young naïve kits than would the larger prairie dogs with strong jaws and razor-sharp teeth.
The delicate cycle of captive breeding began in earnest in March, when we became novice reproductive physiologists. Pairing normally solitary male and female ferrets together for extended periods of time can be dangerous. Long canines and muscles built for taking down prey nearly twice their size when used on each other can result in severe injury or even death. Thus, we carefully monitored the precise timing of when individual females entered estrus, using pipettes of water and microscope slides to perform vaginal washes. Counts of more than 90 percent of cells being keratinized indicated that a female should be ready to be bred successfully. We then placed a sexually active male with the female in an outdoor nest box for three days, hoping they didn’t instantly fight and listening for a struggle in the plywood box as we shut the door.
Following a pairing, we rested the male for three days prior to pairing him again with another estrus female—allowing his seed to restock. We similarly let the female rest, conducting an additional vaginal wash seven days after the initial pairing to determine whether ovulation had occurred. Given that all black-footed ferrets give birth around six weeks post-conception, using this initial pairing date we were able to fix the time when the females were likely to give birth or whelp.
Using this recipe, by June 2002 we produced eight litters totaling thirty-four kits. Thirty-four pinky-finger-sized young with their eyes closed wiggled in a pile of thin fur and pink skin. We left them alone in their indoor whelping boxes with lids closed tight. Just as we were nervous in pairing males and females, we were nervous of the mother rejecting or killing her young. To avoid tipping them into an infanticidal killing frenzy, we kept disturbance to a minimum; at first we opened a nest box lid only to change the bedding every five days. Despite this sensitivity, by July we had lost three kits. Two of the kits, when found, had been largely cannibalized by their mother. Was it a natural death of the kit and the mother simply ate the available carrion, an instinct to take what she could get to continue producing milk for the others? Or was it confusion by the mother, and infanticide as we had feared? Elsewhere in the animal kingdom the non-nurturing urge to kill off another mother’s kits to limit competition is fairly common. In this strange captive setting, did she not realize the kits were her own? Whatever the reason, with so few litters to raise, we hoped it was an isolated event. In another nest box, where one kit appeared to have died from an airway blocked by eating a small square of cardboard bedding material, we blamed ourselves.
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By August, when the kits were well along toward feeding for themselves, Valerie and I began to alternate weekends off and I visited my parents, who had recently relocated for work at the newly created U.S. Geological Survey Northern Rocky Mountain Science Center in Bozeman. My father and I took my mother out to dinner for her birthday. Bad Thai food at a strip mall still tasted good because it was the first restaurant meal I had in a long time. I was at home, but I still felt restless without the ferrets to care for. They had become my crutch, my reason for leaving J, the only justification for a life away from a woman who loved me. I needed something, anything to give me a home, a peace of mind that reaffirmed that I was living a useful life and that I was not just passing through a cycle of travel trailers and temporary jobs. I needed something to give me traction when all idle thoughts seemed to slide toward loneliness. In an act of desperation, I went to the dog pound and adopted a red heeler, named her Abby, bought a sack of dog food, and headed back north to the Hi-Line.
FIGURE 5. Prairie dogs captured in live traps for transport.
When I got back to Malta on a Sunday evening, Valerie had left me a message that an entire litter of six kits died over the weekend. I wondered how, why, and if somehow I was to blame for taking two days off. We shipped the bodies down to the Wyoming State Veterinary Lab in Laramie, uncertain of what went wrong and anxious for the results. We worried that other litters could similarly collapse, so we once again cleaned the cages and disinfected the building, only with a new vigor. In the end, however, we could only leave the mothers to rest and care for their young.
Resigned to the will of the ferret mothers, we knew we could not disturb them with more attention, so we buried ourselves in the work of trapping prairie dogs for ferret food north of Malta. Saving the landowner the time and money of poisoning prairie dogs, in a single week we collected 516 individuals and placed them in elevated cages in an old tin shed with a concrete floor for a two-week quarantine. That was the set period of time during which a disease such as sylvatic plague would have run its course, and if they survived