Wild Again. David S. Jachowski
Читать онлайн книгу.
sizes to avoid extirpation. Mathematical models were developed for an individual species or population that, in their simplest form, were projections of the population into the future based on historical rates of births and deaths. But there was a need to account for a number of obstacles that could make small populations prone to extinction. Small populations within an island of habitat are more vulnerable to unpredictable events like floods or catastrophic fires.
For his dissertation research in 1978, Mark Shaffer developed a formula for predicting the minimum population size of grizzly bears to withstand such unpredictable events, which he termed the “minimum viable population size” (MVP). Over time, others would add to the complexity of such MVP models by including long-term detrimental effects like decreased reproductive output as a result of inbreeding and other factors. The product was hard numbers that could be used by wildlife managers to outline how many animals they needed to maintain, similar to agricultural balance sheets used by cattle ranchers to balance predicted losses against predicted gains, trying to stay in the black. But more than that, by experimenting with the numbers in the model, scientists could begin to say what factors needed to improve to keep the species viable. How would the population respond to a year of good rain that would perhaps result in a sudden 30 percent increase in juvenile survival? What would happen if we stopped a hunting season and were able to decrease adult mortality by 10 percent? These were hard numbers rather than sentiments to bring to politicians and the public when trying to maintain or recover a species.
The risk of species loss and the value in conserving rare populations also were brought to the forefront of public policy. The Endangered Species Act of 1973 (built on the backs of previous acts of 1966 and 1969) was amended to require not only listing of threatened and endangered species, but also designation of critical habitats and development of population recovery plans for those listed species. The National Forest Management Act of 1976 required the U.S. Forest Service to “provide for diversity of plant and animal communities based on the suitability and capability of the specific land area.” In effect, this made national forest managers responsible for maintaining viable populations of native species in their planning areas. Given that endangered and threatened species were typically most at risk of loss, the emphasis was put largely on maintaining or increasing their small populations.
The theoretical and political pieces were coming into place for the conservation of black-footed ferrets, should they ever be rediscovered and brought back from extinction.
• • •
On the morning of September 26, 1981, John and Lucille Hogg were having breakfast in their ranch home, an unassuming white-painted house in the center of a moderately sized ranch in the open, rolling hills and sagebrush flats west of Meeteetse, Wyoming. Up and down the valley the bustle of summer had ended. The rush of growing, irrigating, and cutting hay for the winter had given way to winter preparation. The cows and their calves were coming back into the corrals on homesteads and off the federally leased summer range. Daily chores switched from fences and farming to feeding livestock and preparing for the calving season, assessing the summer’s alfalfa hay crop, and calculating whether there was a need to buy hay to make it through the winter.
The ears of a sleeping rancher must be finely tuned to the sounds of the outdoors, keen to the sound of a bawling cow in early labor, even through the walls of a house in the middle of the night. Lucille Hogg hadn’t slept well because their Australian cattle dog, Shep, was barking and growling outside in the middle of the night. Lucille tossed in bed, settling on the thought that the dog was just learning another lesson on why to steer clear of porcupines. Knowing that there was little she could do in the middle of the night to pull out the hooklike barbs, she decided it could be dealt with in the morning, so she fell back asleep.
Over breakfast, Lucille told John to check Shep for porcupine quills and inspect the damage before the quills corkscrewed too deep into his muzzle and a trip to the vet was in order. Stepping out the front door, John noticed Shep was intact and uninjured, ready for the day. On the front stoop he’d left a carcass, the likely victim of his nighttime ruckus left for show to his owners. As John peered down at the thin carcass, his first reaction was that he had no clue what Shep had dispatched. It was a buff-brown animal with black markings on its paws, face, and tail. Perhaps it was an oddly marked pine marten that had come down from pine forests of the Carter Mountains to the north. Regardless, it looked interesting and attractive enough to pay to have preserved, and John took the specimen to Larry LaFranchi, the local taxidermist. Having stuffed more than his fair share of pine martens, Larry immediately recognized the animal as a black-footed ferret and called Wyoming authorities.
A ranch dog had succeeded where so many professional and backyard biologists had failed, offering a humbling and at the same time hopeful sign that the human footprint had not touched everything. Shep’s singular finding hinted that there were places left forgotten, little understood, where even the most sensitive of species could still persist. A second chance to perhaps learn from these animals and make up for our errors of the past, maybe even resurrect the species.
Within days the State of Wyoming held a town meeting in downtown Meeteetse, where rumor of the find had spread. Why had black-footed ferrets persisted here, on the very western boundary of the prairie? A single isolated dot on the western edge of the historic range map Elaine Anderson would develop that was based on all known museum specimens. Species are supposed to decline from the outside in, shrinking down into the middle where a small refuge remains. This small town of Meeteetse, Wyoming, just south of the more famous Cody, Wyoming, and Yellowstone National Park, was outside the area most thought to survey. But questions of why were secondary to questions of whether there were more, and how many. Wyoming Department of Game and Fish biologists started the meeting by reporting the details of the find and asked the audience if anyone had seen a ferret. Immediately Doug Brown volunteered that he had seen a ferret while working on the Pitchfork Ranch.
In the small ranching community of Meeteetse, stories of where ferrets remained were mixed with fear of what having an Endangered Species on your property could mean. There were rumors that federal restrictions could follow, brought on by enforcement of the Endangered Species Act—the type of legal maneuvering conservation groups still try to use to force the federal government’s hand to pressure private landowners about the use of their land. Despite that the precedent was rare and that most induced management changes occurred on federal land, the fear tactics create a persistent tension between conservation groups and private landowners, with the federal government in the middle. For independent ranchers, relying on the federal government as an effective moderator often wasn’t enough. Policies and administrations changed; ranchers were forced to live with the consequences. Despite the circulating paranoia, with counterculture bravery and vision (traits that, in future years, would be evident in almost every ferret conservation milestone), Jack Turnell, the owner of the Pitchfork Ranch, the Hogg family, and a handful of other ranchers in the vicinity ignored public concerns and allowed researchers onto their land.
Tim Clark and Tom Campbell rented an airplane to map the extent of prairie dogs in the area. They scanned the rolling, open sagebrush steppe grasslands of the Big Horn Basin around Meeteetse that are bounded to the west by the Absaroka mountain range that extend north into Yellowstone National Park. On the ground, federal biologists Hammer and Martin were conducting nightly searches for ferrets on the group of ranches adjoining the Hogg ranch. They walked or drove around the prairie, using spotlights to look for the distinctive green eye shine from the reflective membrane just behind the ferrets’ retinas, hoping that a curious ferret would stick its head out of a burrow. To improve the chances, they also used two search dogs trained to sit when they smelled the scent of a ferret. When one of the dogs smelled the faint aroma of ferret scat or musk and sat down by a burrow, Hammer and Martin, not seeing ferrets themselves but blindly hoping the dogs were on to something, would set live traps at that burrow and surrounding burrows.
On October 29, 1981, more than a month after Shep’s discovery, Hammer and Martin were checking traps in an area where dogs had found scent. Leaving the traps set, they returned to their vehicle and drove off into the night to continue their spotlight search. Looping back around toward their traps, at 6:20 A.M. they saw the flash of something running across the road in front of them and periscoping its head out of a burrow. They had never seen a ferret, but they thought it looked about