In green circles it is widely held that humans are responsible for most of the significant environmental changes and that the condition of wildlife is a good measure of the consequences of those changes. This is generally true, but an important qualifier is often overlooked. There is not a single, universal wildlife barometer but rather innumerable ones (at least as many as there are species of animals), and many of them give different, often contradictory, readings.
For example, 200 years ago mountain lions were fairly common east of the Mississippi. Now only a relative handful are left because people intentionally exterminated them and at the same time were busy altering their habitat. On the other hand, woodchucks are much more plentiful than they were when Europeans arrived in those parts. The reason is that this species does better in open, grassy and brushy country than it does in heavy forests of the sort that originally covered much of the eastern half of the continent. During the past few centuries, while clearing and rearranging the land for their own purposes, people inadvertently created millions of acres of splendid new woodchuck habitat: meadows, fencerows, highway berms, gardens, lawns and the like. If the condition of wildlife is to be used as a barometer of environmental quality—good or bad—the question needs to be asked: Good or bad for whom?
There are two categories of beasts that, like the woodchuck, have prospered because of recent human works. The first and most ecologically significant one is made up of hardy, adaptable species that exploit approximately the same resources we do. Among many other species, carp, badgers, beavers, Canada geese, crows, gray squirrels, assorted mice and rats, opossums, raccoons, sparrows, a number of insects and other invertebrates are not simply holding their own, but they are increasing their numbers and range because they like, biologically speaking, what we have done to the countryside.
In the second beneficiary class are creatures that in the very recent past were thought to be so rare or in such imminent danger of extinction that we humans were inspired to make a massive national effort to assist them. Among the most prominent species in this category are alligators, bald eagles, condors, masked bobwhites, red wolves, peregrine falcons and whooping cranes. All of which, as species, are faring much better now than they were 25 years ago.
April 7, 1991
In this regard, the most spectacular and unexpected turnaround has been made by the black-footed ferret (SI, Oct. 13, 1980). These weasellike residents of the prairie regions are still among the rarest of North American mammals, but during the past six years the survival prospects of the species have dramatically improved and may be stronger now than at any previous time in this century.
Black-footed ferrets (hereafter BFFs) are naturally nocturnal, semisubterranean creatures that inhabit the tunnels dug by prairie dogs and prey exclusively, so far as anyone knows, on their hosts. In consequence, BFFs have never been much studied in the wild or, for that matter, often seen. In fact, they were not known to science until 1851, when John James Audubon collected the first specimen. During the next 50 years, occasional ferret signs and carcasses were found, but during this century reports of the animals became increasingly infrequent. It was—and still is—assumed that they declined drastically as a result of farming, land development and, especially, because of public poisoning programs aimed at eradicating prairie dogs. (Western agriculturists dislike these rodents, which compete with cattle for grass and dig up rangeland.)
In the mid-1960s, the BFF was placed at the head of the list of endangered North American mammals. Federal biologists were dispatched to South Dakota—whence had come the best and most recent BFF reports—to look for them. The scientists found so few animals that it was decided to live-trap some of the remaining BFFs and send them to the federal Wildlife Research Center in Laurel, Md., where it was hoped the ferrets would breed in captivity. From 1971 to '73, nine BFFs were caught in South Dakota and shipped to Maryland. All died in captivity and left no offspring. Thereafter, no more ferrets were found in South Dakota or anyplace else, though federal, state and private researchers hunted for them throughout the Great Plains for the rest of the decade. By 1980, many zoologists thought the species might be extinct.
This assumption, though a reasonable one, was false. In September 1981, near the village of Meeteetse in northwestern Wyoming, a ranch dog presented his owners with a BFF carcass.
Immediately, assorted BFF researchers descended on the Meeteetse area. By 1984 they had, astonishingly, found 129 BFFs living in a 7,400-acre tract of isolated agricultural land.
Along with a great deal of scientific activity, the rediscovery of living BFFs in Wyoming touched off a political dispute. Previously, research on endangered species had been supervised by the U.S. Department of the Interior through its subsidiary, the U.S. Fish and Wildlife Service. This graveled—and still does-some state authorities, who feel the feds are prone to use such projects as a wedge to force their way onto other people's administrative turf. In 1981, when the Meeteetse BFFs were found, the Secretary of the Department of the Interior was James Watt, who despite his national office was an ardent states' rights man and fiercely opposed to "creeping federalism." It was decided that while both state and federal officials would be members of a black-footed ferret recovery team, the Wyoming Game and Fish Department would be the "lead agency," that is, the ultimate authority.
As part of the protocol, Tom Thorne, a veterinarian employed by that Wyoming department, was made responsible for the welfare of the living BFFs and, as such, was given veto power over most field activities. He could halt any trapping procedures that he did not consider were in the animals' immediate best interests.
Thorne, who is stationed at the University of Wyoming in Laramie, is one of a handful of wildlife veterinarians in the nation and, among other things, a strong-minded man who is less enamored with hands-on research than are many laboratory zoologists. (For example, in 1983 Thorne called a halt to a plan by federal biologists to put radio collars on the Meeteetse ferrets. His reasoning was that the data collected might not be worth the risk of stress involved in capturing the endangered animals.) There was grumbling that Thorne was a zoological Luddite, but he stuck to his guns. As it turned out, that was good for the BFFs and probably for science in general.
In the spring of 1985, state and federal ferret authorities once again agreed that there were enough of the animals at Meeteetse to justify capturing a few that autumn to try breeding them in captivity. However, the plans of the BFF recovery team were shortly overwhelmed by nature. During the summer of 1985, sylvatic plague, a contagious rodent disease, broke out among the Meeteetse prairie dogs and began to kill them. Field observers suspected that entire families of prairie dogs (females and their litters) were "winking out"—a euphemism for dying.
Beyond killing off the prairie dogs on which BFFs prey, there was no evidence that this plague adversely affected them. But because of the publicity surrounding their precarious state, there was a great outcry that the disease might kill them and that the authorities must do something. In response, federal and state agencies used a hundred or so volunteer and temporary employees to dust thousands of prairie dog tunnels with a pesticide. The objective was to exterminate fleas that were known to spread sylvatic plague among prairie dogs. Despite the effort, the prairie dog and ferret populations continued to decline.
Still, the plans to revive a BFF captive breeding program went ahead. Six ferrets were captured in the fall of 1985 and placed under Thorne's supervision. All six of the BFFs died in the lab. The cause of death was found to be canine distemper, which is invariably fatal to BFFs and against which they do not seem to develop a natural immunity. At this point, it became apparent that distemper, not plague, had been causing the decline in the Meeteetse ferret population, and the well-intentioned pesticide work had been a distraction.
Most probably the Meeteetse ferrets naturally contracted distemper from other wild animals—badgers, skunks or coyotes—who are vulnerable to it and who also raid prairie dog colonies. However, there remains the suspicion that the virus—perhaps picked up from household pets—may have been brought in on the clothing of researchers, or "flea stompers," as Thorne came to call the pesticide applicators.
Thorne forthrightly blames himself for the loss of the six captured wild ferrets. "I should have immediately isolated all of them until we could find out what was happening. But I didn't and that was ignorant." (Thorne has a habit that is unusual among professional zoologists: He admits to mistakes, confesses he doesn't know this or that when he doesn't, and will say that while what he has done or plans to do seems reasonable, it may prove otherwise.)
Now armed with the knowledge of the specific disease that was threatening to wipe out the last remaining wild BFFs, the team captured six more Meeteetse ferrets in what then seemed a last-ditch effort to save the species from extinction.
In the summer and fall of 1986, Dean Biggins, a federal ferret researcher, and some of his colleagues were able to catch 11 more ferrets (four males and seven females) at Meeteetse, and with the six who survived the previous winter they were sent to a newly built, isolated research facility in Sybille Canyon, some 45 miles north of Laramie. This ferretry is particularly impressive, because when it was designed by Thorne and others, nobody knew much about what could and should be done for the animals. Most obviously the Sybille facility is a high-security one. Visitors are seldom permitted in, and those who are must take showers and put on sterilized clothing before entering the gymnasium-sized building that houses the BFFs.
The ferret cages are commodious. Each contains two den boxes that are ingeniously connected by tubing that simulates prairie dog tunnels. The den boxes are designed so that video cameras can be inserted without disturbing the animals. The animals can be constantly monitored on a bank of TV screens in an adjacent room.
Some 60 Siberian polecats are held in a second building at Sybille Canyon. The nucleus of this group of central Asia natives was donated by a fur farmer (commercially, they are referred to as fitch). The polecats look much like the BFFs and are a closely related species, but they also are relatively common and prolific animals. At Sybille, they are used as surrogate research animals and occasionally as foster mothers for BFF kits whose own dams cannot or will not nurse them.
Though their rarity has required extraordinary precautions, the BFFs have proved not much more difficult to maintain than cage-reared mink, according to Don Kwiatoski, another veterinarian who sees the animals on a daily basis. He says that the BFFs adjust nicely to captivity, eat well (a mixture of commercial mink food, fresh hamster, rabbit and, occasionally, prairie dog meat) and, if handled properly, show few signs of stress.
Despite the fine facilities, the first efforts to get the ferrets to breed, in the spring of 1986, were unsuccessful. The six distemper survivors were two juvenile males and four females. One of the latter mated briefly but did not become pregnant. The other females did not come into breeding condition. Thorne believes that the BFFs' long isolation had traumatized them.
The 1987 breeding season started equally badly. For the most part the females in heat violently rejected the males. "They just flat out whipped and intimidated them," Thorne says succinctly. It then seemed that the elaborate BFF recovery program might well be for naught because of sexual incompatibility. Until better techniques are developed, artificial insemination of ferrets can only be accomplished surgically, which makes it unacceptably difficult and risky. However, the 1987 mating season did show signs of progress thanks to a remarkable animal who, if this species survives, should be remembered as a hero-founder.
After capturing the 11 ferrets in the summer and fall of 1986, Biggins and the other federal field researchers found signs that indicated there might be another animal still in the Meeteetse prairie dog colony. It would prove to be an extremely elusive and wary creature. Over the course of the next four months, the feds caught only fleeting glimpses of it and were not able to lure the animal into a trap until February 1987. It proved to be a mature male, and from the evidence of the healed wounds on its muzzle, a veteran of combat against other beasts or perhaps competing ferrets. Biggins named him Scarface and sent this last, so far as is known, of the wild BFFs to Sybille, where he was first put into one of the eight isolation wards. However, Thorne and Kwiatoski saw that Scarface was in fine sexual fettle. Desperate to get some breeding action, they brought a female to his quarantine cage and went to watch what happened on their video screens. There was a brief but fairly ferocious fight, and then, says Thorne, "he just plain overpowered her."
Subsequently, Scarface did the same to a number of other Meeteetse females. Thorne thinks that beyond being an idiosyncratically aggressive BFF, Scarface was an experienced animal, one who had learned the rough courtship rituals of his kind while in the wild.
In 1987 seven kits were weaned at Sybille, the first captive-bred BFFs to survive—as they still do. In 1988, there were 34 young, in 1989 another 58, and in 1990 an additional 80 kits survived through weaning. Of the current population of cage-reared BFFs, over half are immediate descendants of Scarface. After his Success, other males mastered ferret mating games, and in 1990 Scarface was not permitted to breed with other BFFs, the concern being that his genes may become overrepresented in the species. However, he remains sexually enthusiastic and able. To keep him in service, so to speak, he has been mated with several Siberian polecats, which have produced hybrid offspring, a matter of considerable interest to taxonomists.
As of the end of the 1990 birthing season last fall, there were 180 captive BFFs at Sybille Canyon. The astonishing success of the breeding program has enabled the ferret recovery team to do something about a situation that has concerned it from the start—that a natural catastrophe or unexpected epidemic might wipe out the sole remaining BFF colony, there being no definite proof that any BFFs remain in the wild. Not wishing to keep all their BFFs in one basket, from 1988 to '89 the scientists at Sybille sent 10 BFFs to Front Royal, Va., where the National Zoo of Washington, D.C., operates a research facility. Another 21 animals were shipped to the Omaha Henry Doorly Zoo. In addition, zoos in Colorado Springs and Louisville have already received BFFs, and Toronto and Phoenix will get some this fall. Despite the expense, zoo directors have been enthusiastic about having a BFF project because of the scientific honor and publicity that come with it. These institutions will not be allowed to put the BFFs on public display—at least for several years—and have been required to build and pay for facilities modeled after Sybille, in the hope that other breeding colonies can be established. If there is progeny at one of these other locations, the ferret recovery team in Laramie will determine what to do with the offspring.
With captive ferrets now apparently in good supply, there is new optimism that some of them can eventually be reestablished in the wild. If all continues to go well, the first attempt will be made this year. The present plan is that after the BFFs have been given some retraining as hunters, about 50 captives—divided into litter groups, i.e., siblings of the same year—will be released near the town of Shirley Basin, in central Wyoming. Other prairie dog colonies in Wyoming, Montana and South Dakota are also being surveyed as subsequent release sites.
There is some opinion that if these returnees do not adjust immediately, they should be returned to protective custody. However, Thorne believes that once they are set free, they should remain so, whatever their fate. "We can give them some help in the beginning, by selecting sites that appear to be disease-free, keeping away local predators, doing some supplemental feeding. But sooner or later they have to make it on their own. Otherwise we will end up with a permanent zoo species. The whole idea is to reestablish ferrets as part of our native fauna."
The unexpected discovery of ferrets at Meeteetse in 1981 has sustained hopes that there may still be more of them hidden away in some corner of the Great Plains. Biggins, the federal ferret man, and other researchers have continued to search for them. In the past few years there have been what Biggins considers to be promising reports from Colorado, Utah and South Dakota, but not since Scarface was trapped in 1987 has anyone known with certainty of a wild BFF. (To encourage the" search, the recovery team offered a $10,000 reward to anyone who could direct them to a living black-footed ferret. The reward stimulated a number of calls from people who honestly mistook weasels and domestic ferrets for BFFs, and one hoax was based on a doctored photograph. The offer was canceled.)
Sybille Canyon is a scenic place that is enclosed with red rock formations sculpted by wind, water and frost. The ferret factory is much less attractive visually, but in other respects it is as impressive as the red rocks, an exhibit of one of the true wonders and powerful forces of the world—human nature. Homo sapiens-bashing is popular among environmental True Believers, who often point out what destructive, greedy and hubristic creatures we are. And we often have been. By way of a small example: As of four years ago, we seemingly had reduced the known population of BFFs to 18 individuals.
On the other hand, we have apparently been able to summon the ingenuity and resources (about $10 million worth of them so far) to rescue this same species from the brink of the abyss of extinction. We have done so not for pragmatic reasons or material gain but because we are naturally moved by compassion, curiosity and guilt. Metaphorically, the saga of the black-footed ferret illustrates some of the worst, best and most distinctive of our traits. Which of those elements of human nature we emphasize and develop will have considerable influence on nature in the future.