Seeking the Missing Lynx
Researchers use a novel technique to pin down the exact status of the declining lynx
Feline eyes catch a twisting movement in a Montana forest. Head cocked sideways in seeming puzzlement, the lynx contemplates its discovery: an aluminum pie plate dangling from a wire. The cat reaches up to swat the bauble, but stops in mid-motion as an alluring aroma hits its nostrils. Homing to the smell´s source on a nearby tree trunk, the lynx vigorously rubs one cheek, then the other, against the fragrant find. The cat departs but leaves behind several telltale hairs, mute testimony to its ethereal presence.
Lynx have always been shadowy players on the American wildlife scene. Even the scientists who study these cats rarely see them. But now, thanks to an innovation by John Weaver, a field biologist for the Wildlife Conservation Society, lynx may surrender some of their mystery. Weaver´s hair-raising scheme for enticing lynx to tell their secrets uses such diverse components as carpet, nails and DNA analysis. If successful, this marriage of high-tech and low-tech methods could eventually tell scientists how many lynx are out there, what the cats´ genetic health is and what types of habitat they prefer. Such data are especially important in the lower 48 states, where the small lynx population needs help if it is to survive, conservationists say. "With information like this," says Weaver, "we may eventually achieve appropriate management for lynx."
The lynx is the rarest of the three widely distributed wild feline species in Canada and the United States. An adult lynx may stand 20 inches tall, but weighs only 20 to 30 pounds--only twice the heft of an average house cat. This cat has a stubby tail, mottled grayish-brown pelage, a ruff of facial fur, pointed hair tufts rising from its ear tips, long legs and oversized, snowshoelike feet. One cousin, the cougar (also called mountain lion or puma), outweighs the lynx by 140 pounds or so and preys mostly on deer, elk and other large animals. Although cougars were long ago extirpated from the eastern half of the country, they thrive in the wooded and mountainous West.
The other relative is the bobcat, which has shorter legs and smaller feet than the lynx--making it less maneuverable in deep snow. Some biologists believe the bobcat and lynx resulted from two separate colonizations of North America by a single species--the Eurasian lynx. According to this theory, the first immigrants occupied the warmer regions, where, in competition with wolves, coyotes, bears and other predators, they developed an aggressive temperament. This feline became the bobcat. The second wave of immigrants lacked the pugnacious personality required for life among rivals, so they remained in the north. This animal evolved into the modern-day lynx.
Today, the bobcat prospers in the United States, with a population estimated at between 700,000 and 1.5 million. The lynx, however, has not fared as well. Although never abundant in the lower 48, lynx occupied parts of most northern states and western mountainous areas as far south as Utah and Colorado before European settlers arrived. But settlement and trapping severely reduced their numbers during the past century. The cats were especially hard hit during the late 1970s and early 1980s, when prices for their fur peaked at almost $600 per pelt. Today only Maine, Montana and Washington have breeding populations--perhaps fewer than 700 cats total. A few lynx also show up occasionally in Idaho, Utah, Colorado, Wyoming and some Great Lakes states. Lynx are better off in Alaska and Canada; the populations there probably total in the tens of thousands.
Lynx make a living largely by hunting snowshoe hares. "Hares and lynx evolved together in the deep snow of the boreal forest," says Mike Roy, a biologist with the National Wildlife Federation in Missoula, Montana. "Over time, the cats have become specialists, relying almost exclusively on a single prey species." About one hare every two or three days is required to fuel the lynx engine. If hares are scarce, lynx reluctantly dine on grouse and smaller birds, rodents and occasionally even caribou calves. Although adult lynx usually survive periods of hare scarcity, kittens may starve as their mother consumes all the prey she is able to catch. When food is scarce, females produce smaller litters or successfully rear fewer young. Before long, the lynx population, like the hares´, plummets.
Along with the unpredictability of their major food source, lynx face challenges from habitat destruction and fragmentation. On one hand, tree removal spawns the growth of seedlings and--eventually--the creation of prime hare habitat, which bodes well for lynx. But logging may disrupt the cats´ travel, because they are reluctant to cross large clear-cuts. And loggers may leave behind the wrong mix of timber types. "Lynx require both early forest stages where hares hang out and old growth for denning," says Mike Roy.
Roads are also a problem, both inside and outside the forest. "Too often, our highway systems break up the habitat into little pieces," says Bill Ruediger, wildlife biologist for the U.S. Forest Service´s northern region. There are 63 major highways in the northern Rockies, says Ruediger, and this is prime habitat for lynx and other carnivores. Not only do these roads fragment territory and isolate lynx populations, they also result in dead animals. It´s difficult to quantify the number of lynx road-kills in the northern Rockies, Ruediger says. He notes, however, that an effort to reintroduce lynx to the Adirondacks of New York several years ago failed largely because "they were getting hit as fast as they were brought in."
An even more basic problem is that so little is known about lynx. "They´re reclusive, elusive and exist mostly in low densities in remote areas," says Gary Koehler, a lynx expert and research biologist with the Washington Department of Fish and Wildlife. Much of what is known about lynx has come from research in the far north. In the western states, only five studies have ever looked at lynx, and most of these followed only a few radio-collared cats for a brief period. Information on demography, dispersal and other vital subjects has been notably lacking. "Until a few years ago, we weren´t even sure which states lynx occupied," says Ruediger, who also serves as chairman of the Western Forest Carnivore Committee. There simply has been no reliable way to tally lynx, measure dispersal, study the cat´s genetics or chart population dynamics. But Weaver´s new research tool may change that.
In 1991, Weaver happened upon a lynx while doing wolf research in Canada´s Jasper National Park. "We sat and watched each other for 20 minutes, and I became instantly enthralled with these wild cats," he recalls. That fascination grew when Weaver later bought a female lynx kitten from a fur farm. Living in a kennel behind Weaver´s home in the Montana foothills, Chirp (as Weaver called the cat) taught the biologist a lot about lynx behavior.
While Weaver was learning about lynx, other scientists were making significant breakthroughs in the analysis of DNA, the genetic blueprint for life contained in virtually every living cell. Each individual´s DNA is unique, a kind of chemical signature, and during the 1980s, researchers learned to tell if two (or more) DNA samples came from the same person. Before long, biologists began using DNA to study wildlife. At first, most DNA work required that wild animals be captured for the collection of blood or other tissue. Early in this decade, however, wildlife biologists Steve and Marilyn French, working in Yellowstone National Park, changed that by extracting DNA from grizzly hair left behind at baited feeding sites.
Still, DNA analysis of wild felines was difficult. Compared to bears and many other species, cat DNA varies less among individuals, which means a more sophisticated analysis is required to identify individual felines. Only in 1995 did Stephen O´Brien, a researcher with the National Cancer Institute in Frederick, Maryland, develop the necessary techniques for full DNA analysis of feline tissue.
In Montana, Weaver was intrigued with the notion of studying lynx via DNA. "I wanted to see if it was possible to develop a noninvasive manner of collecting population data on elusive species like lynx," he recalls. For decades, the tool of choice for studying wild felines had been radio telemetry, which required that each study animal be captured, drugged and have a radio transmitter (usually in the form of a collar) attached to it. Weaver knew that if he could somehow collect hair from lynx, he might add to the meager data base on these creatures without disturbing them.
Since no one had ever before attempted to collect DNA from a population of wild felines, Weaver was on his own. In Yellowstone, the Frenches had collected grizzly hair by stringing barbed wire around bait stations, but surely lynx would simply jump over or otherwise avoid such wire. Then one day Weaver watched Chirp rub her cheeks against a post in her kennel, leaving a few hairs behind. Would it be possible, he wondered, to get wild lynx to do what all felines do anyway--rub?
For months, Weaver sought the best way to collect hair from unseen lynx, using Chirp as a one-cat testing laboratory. Equine curry combs, sticky flypaper and Velcro all proved less efficient than a simple 4-inch-square piece of carpet with small nails poking through it. Nailed to a tree trunk at lynx height, this feline hairbrush made the perfect scratching station for a species of compulsive rubbers.
Meanwhile, several conservation groups had banded together to help save the lynx from extirpation in the 48 states. In the early 1990s, they began petitioning the U.S. Fish and Wildlife Service (FWS) to list lower-48 lynx populations as threatened or endangered under the Endangered Species Act. "Lynx exist in scattered, small populations dependent on isolated and declining habitat," says Mitch Friedman, executive director of the Northwest Ecosystem Alliance, a regional conservation group. "The consensus among biologists was--and is--that lower-48 lynx need to be listed."
In Washington, D.C., however, FWS officials denied the petitions, despite support for listing from their regional offices and field researchers. Last March a federal judge ordered the agency to reconsider its position, and in May the FWS concluded that the lynx does indeed warrant protection under the Endangered Species Act. The agency, however, still refused to list the cat. "Unfortunately, our resources are limited and other species are in worse condition and require more immediate action on our part," says Ralph Morgenweck, director of the agency´s Mountain-Prairie Region. In rendering its latest decision, the FWS called for additional lynx studies to gain more information about this cat. Conservationists have taken the matter back to court.
As the listing controversy dragged on, Weaver continued his experiment. With help from trappers, he concocted an olfactory lure few lynx would likely resist. Though he won´t divulge the exact formula he rubs into each carpet square, one important ingredient is catnip. His setup received rave reviews from lynx and bobcats at several fur farms. In the summer of 1996, Weaver took his innovation to the rugged mountains of the Kootenai National Forest in northwest Montana, setting up more than 100 rubbing stations. Near each rubbing pad, he dangled a chicken wing or piece of aluminum pie plate to attract the always-curious cats. In theory, the cat would then get a whiff of the lure and follow its natural urges to deposit hair on the pad.
But no one had ever tried such a thing. Would wild lynx home to the stations? Would they rub against the pad? Would they deposit enough hair? Even Weaver had his doubts. "More than once it occurred to me that all this might be a waste of time," he says. It was not. By fall, 39 pads had collected hair, although obviously not all from lynx. From each pad, Weaver carefully removed about a dozen hairs (strands complete with their microscopic bulblike roots are best) and sent them to the genetics laboratory of the Wildlife Conservation Society in New York. Scientists there had helped pioneer wildlife DNA techniques, and the Society´s lab was one of only a few in the world capable of analyzing DNA from feline hair.
Last spring, the lab´s initial analysis validated Weaver´s vision and confirmed the project´s most important goal: proving the method works. Twenty-eight of the rubbing pads had indeed collected lynx hair. Although some of the hair samples probably represent the same cat visiting more than one rubbing pad, several lynx apparently still prowl the Kootenai forest, a fact not previously documented. More refined analysis of the samples will determine cat gender and tell who is related to whom, information biologists can use to assess the population´s genetic diversity, an important indication of its health.
Already, Weaver´s innovation is being hailed as a breakthrough in feline--and possibly other carnivore--research. "DNA hair analysis has tremendous potential for answering important questions about how many lynx are out there and gauging their genetic health," says Koehler.
For starters, hair sampling might provide hard-to-get population data on this elusive species--exactly the kind of information the FWS says it needs before listing lynx. "A coordinated lynx inventory throughout the country, done with rubbing pads, could reliably establish this cat´s true status," says Weaver. Already, more rubbing pads have been set out in the Kootenai, in Washington State and in Banff National Park in Alberta, Canada. Also, by plotting the locations of rubbing pads on a forest map, hair collection can help identify the habitats lynx prefer.
Although techniques are still being refined, hair collection and DNA analysis may revolutionize the study of some wild species, as the use of radio telemetry did in the 1960s. "This comes pretty close to being a magic glass for looking at rare, elusive carnivores," says Weaver. For lynx, it may signal another subtle shift: For decades, biologists have tied lynx prosperity to hares. This connection is likely to continue, but maybe now it should be spelled h-a-i-r-s.
Writer Gary Turbak lives in Montana.
Putting Lynx in the Limelight: NWF Takes Action
Lynx have been in the shadows too long, contends NWF biologist Mike Roy. "Lynx numbers have declined dramatically in the lower 48 in the last quarter century," he says, "but other, perhaps more-appealing carnivores get most of the attention." NWF has been working for several years to help redress this imbalance. In 1992, NWF drafted a petition for listing lynx under the Endangered Species Act. More recently, NWF has worked with Montana officials to limit lynx trapping in the state, and it has encouraged federal officials to close roads in national forests to help protect lynx and other sensitive species. To stay informed on issues relating to lynx and other western carnivores, write: NWF, Northern Rockies Project Office, 240 N. Higgins, Missoula, Montana 59802.