It was a bad way to get famous. But if not for the scandal–inflamed headlines, outraged politicians, and rumors, rumors, rumors–the study of wildlife by analyzing stray tufts of their hair might never have gotten much public notice at all. Hair sampling, however, has certainly gotten widespread news coverage. The furor started last fall over a U.S. Forest Service project to detect lynx in the northern United States by collecting fur snagged on rough pads that scientists had attached to trees. The project has political implications because finding lynx, a species protected by the federal government as a threatened species, could spark arguments about closing off portions of woodland to logging and other commercial uses.
Newspapers set fur flying in December 2001, with reports that seven field workers had contributed captive lynx hair labeled as if it had come from the wild. The collectors responded that they were merely testing the quality of the laboratory analysis. Government evaluators were called in. The General Accounting Office (GAO) released the results of its investigation on March 6 at a congressional hearing.
This lightning rod of an episode has sizzled with commentary about hidden agendas, abused trust, enviro-outrages, and much more. Not much of the debate has been about the science.
Fur sampling has recently caught the attention of various biologists trying to study animals in ways that don’t change behavior. Success with this method requires cutting-edge genetics as well as old-time woods know-how, such as what stinks enough to attract the animals.
Since the early 1990s, researchers have been applying the technique to spectacled bears, cougars, foxes, pine martens, chimpanzees, gorillas, and many other species. For examples of the basic fur-sampling methods with their trials and triumphs, consider North American bears and Australian marsupials.
Bear researchers pioneered genetic fur sampling, according to Michael Proctor of Kaslo, British Columbia, and he can count the reasons. Start with 500 for the pounds that a big adult male grizzly in Proctor’s part of Canada can weigh. Add 10 for the number of front claws, each several inches long, and another 1 or 2 for the cubs that a typical mother grizzly defends fiercely. However, for the number of grizzlies that a person tramping northern forests is likely to see, add a big fat zero.
Subscribe to Science News
Get great science journalism, from the most trusted source, delivered to your doorstep.
“Bears are really hard to count in forests,” says Proctor.
In the early 1990s, Pierre Taberlet of the University of Grenoble in France led an effort to study DNA in bear scat and tufts of fur caught on a scratching post wrapped in fence wire. His team thus identified the last 15 or so brown bears still surviving in the Pyrenees.
Proctor traces the notion of studying North American bear fur to an informal population biology colloquium attended by Canadian biologists Bruce McLellan, David Paetkau, and perhaps a bottle of scotch in a hotel room in 1995. Soon after, a wilderness-savvy student–Proctor–was looking for ideas for a bear project, and McLellan suggested that he try collecting fur.
In his project, Proctor and his colleagues surrounded a strongly scented area with barbed wire strung tree to tree. Brushing against snags, the researchers reckoned, wouldn’t much bother an animal wearing a grizzly coat.
A roll of barbed wire weighs 100 pounds, so Proctor persuaded a friend with a helicopter to help him lug the fencing into the wilderness. By the time Proctor had flown home and hiked back in, the wire ball was already dotted with fur. “A bear had been using it as a scratching post,” he says.
The hair trapping stations that Proctor and his colleagues finally developed offered various exciting scents splashed on the ground. Proctor also hoisted a burlap bag of strong-smelling dead animals high in a tree to act as a beacon. A mini-corral of knee-high wire tugs a bit of fur, ideally with its follicles, from bears crossing the fence to reach the marvelous smell. The follicles, not the hair strand itself, yield the DNA that the researchers use.
“There’s an artistic lore built up on attracting bears with scents,” says Proctor. “I take a barrel of dead fish and leave it in the sun for a year. ” As for the odor of a finished batch, “we’re talking deadly,” he says.
To count bears, the researchers scattered 64 stations over a 4,000-square-kilometer sweep of wilderness near Golden, British Columbia. A station covers no more space than a small kitchen, says Proctor. Each one “is like a needle in a haystack,” says Proctor. “The miracle is that it works.”
The researchers didn’t count on attracting every bear in their wilderness. Instead, they modified a census-taking method called mark-recapture. In this approach, a researcher traps individuals of the species of interest, marks them, and then sets them free. The researcher then traps animals several more times, keeping track of how many of each haul already have markings and how many are new captures. From these numbers comes the estimate of the total population.
The bear researchers compare the DNA of bears snagged during one trapping session with that of those snagged in later ones, and they work out estimates of the grizzly population in their test area.
Since the first bear count Proctor and his colleagues ran, the method “has taken over the world,” he says. So far, there have been 14 bear-hair-trapping censuses in British Columbia and Alberta, and he’s seen colleagues elsewhere tune the method to their own bear issues.
The largest bear-hair census in the United States to date is providing the first reasonable estimate of how many grizzlies and black bears roam Glacier National Park, says Kate Kendall of the U.S. Geological Survey (USGS) in West Glacier, Mont., who coordinates the project. For decades, estimates had been based on the notoriously fickle numbers of sightings of what might or might not be the same individuals. This information yielded a figure of 250 or so grizzlies living in the park. Two years of hair trapping and genetic analysis, however, has raised the estimate of grizzlies to about 400, Kendall says.
She and her colleagues collected bear hair that naturally snagged on underbrush near trails and caught in traps styled after Proctor’s. To prepare the lure for the hair traps, Kendall arranged for barrels of dead fish and decaying cow blood to age in a shed at a local sewage-treatment plant, where staff complained about the smell.
Even before the scent was deployed, it attracted a mystery writer, Nevada Barr, who was plotting a book around bear censusing in the park. She was the only person ever to ask for a tour of the brew shed, says Kendall. The novel, Blood Lure (2001, Putnam Publishing Group), begins with the heroine reeking of bear attractant.
Hair trapping doesn’t replace other study techniques so much as provide different types of information, Kendall explains. The technique doesn’t yield the specific physiological profiles and diaries of daily activity that researchers get when they trap an animal, attach a radio transmitter, and then follow the signal. However, radio-collaring requires so much skilled person-power, especially for huge, far-ranging beasts, that researchers are limited to small sample sizes.
Michael Vaughan of Virginia Polytechnic Institute in Blacksburg chose hair sampling to learn where a bear crosses the road. In the Great Dismal Swamp along the Virginia–North Carolina border, highway engineers are upgrading a two-lane road on the swamp’s eastern border. Vaughan fears that a more formidable highway might isolate the swamp bears. Their forays across the road now maintain their genetic diversity.
In 2001, Vaughan and his colleagues stretched a strand of barbed wire for 7 miles along the highway and picked off hair that it snagged over nine months. Bears were indeed crossing the road, but mostly along one stretch about a mile long. Fortunately, the highway engineers had noted especially soggy terrain there and were planning to elevate the roadway. Vaughan predicts that bears will venture under the stretch of elevation.
How creatures move in big areas is exactly the sort of question that hair trapping can answer, Proctor says. He’s built up a considerable bear database. One of the patterns that’s emerging, he says, is that highways discourage roaming by female bears much more than by males.
Proctor is also using his database to confirm how young grizzly bears leave Mama and go out on their own. “It’s not just ‘OK, I’m a teenager and I’m moving out,'” he says. He finds that young grizzlies tend to settle close to their mother’s home.
Australia’s two species of hairy-nosed wombats are a far cry from grizzly bears, but they, too, are good candidates for fur trapping. “They’re like giant prairie dogs,” says Faith Walker of Monash University in Clayton, Australia, as she struggles for a North American analogy.
About knee-high to a person, wombats dig wide, interconnected burrows. Walker has wormed herself some 20 feet back into a particularly palatial one. The complexes, with their mounds of excavated dirt, are so large that they are visible in satellite images.
After a night of foraging alone, a wombat spends its day in burrows. Judging by a captive animal growing up in a preserve, Walker suspects that wombats sleep on their backs with their feet in the air. On her daily rounds of burrow entrances, Walker says, she’s heard snoring.
“They’re very, very shy,” Walker reports. Even for a wombat-savvy tracker flashing a spotlight in the right place at night, she says, “what you see is a rear end running away from you.”
Researchers have not been very successful in studying wombats with live-radio collars or traps. “They don’t have much neck,” says Walker. Also, they burrow so much that they often knock off their transmitters. Confinement in traps drives wombats to thrash and struggle.
Researchers have turned to hair sampling. Walker stretches double-sided, highly sticky carpet tape between garden stakes in front of the entrance to a burrow. The next morning, if she’s lucky, she can select one or two hairs from captured tufts for identification.
Walker is studying the southern hairy-nosed wombat. She has good data on who’s related to whom, she says, and she’s found that unlike most animals, the wombat females move out of the area and the males stay near their birthplace.
The Queensland Parks and Wildlife Service is also collecting hair tapes. The scientists there are using them to monitor the highly endangered northern hairy-nosed wombat, which numbers 150 or fewer in the one wild population.
Now, back to the lynx. In the 1990s, the Fish and Wildlife Service began to consider listing the Canadian lynx on the U.S. Endangered Species List. Last month, Kevin McKelvey of the Rocky Mountain Research Station in Missoula, Mt., explained at a congressional hearing that although biologists knew of a few remote populations of lynx, they wanted to check for current inhabitants throughout what had once been the lynx’s range. Investigators turned to hair sampling because the animal they sought is hard to spot in the wild.
McKelvey and his colleagues designed little scratching pads that field workers fastened at lynx height to trees. To lure lynx, the researchers attached eye catching pie pans and scented the pads with an intriguing beaver gland secretion mixed with catnip oil. Starting in 1999, collectors in 12 northern and western states set out more than 13,000 of these pads. Any hair that showed up was sent to the lab of Scott Mills at the University of Montana in Missoula.
An earlier Forest Service study, with a different lab, used fur snagging to see if any lynx still roam the Cascade Range of Oregon and Washington. In 1999, preliminary results pointed to 14 places, including spots in the Wenatchee and Gifford Pinchot National Forests. Late in 2000, the study leaders asked hair-genetics pioneer Paetkau to take a look. He found evidence that the results were implausible; widely scattered DNA samples seemed to have come from the same lynx. When he extracted more DNA from the fur samples, he found evidence only of bobcats.
The new lynx survey also called for hair samples from that region. According to the report from GAO, one of the workers collecting the hair contacted a coordinator of the lynx survey in 2000. The collector said that he had taken fur from a captive lynx and submitted it with a data sheet that indicated the sample came from the wilderness in this region. He said that he was trying to see if the lab really could identify a lynx.
Government investigations found that six more fur collectors had submitted fake samples during 1999 or 2000. These were the only lynx samples labeled as coming from the Wenatchee and Gifford Pinchot National Forests.
His lab did identify them correctly, says Mills. He pointed out, however, that the test design did not allow for such mislabeled samples. Instead, the lab had processed test samples before receiving fur from the more than 500 collectors.
Also, the lab processed a bit of known lynx DNA and a blank along with each sample submitted.
Once Mills heard about the mislabeled samples, the data were removed from the analysis. However, he told the hearing, the hair alone would not have been enough to make the surveyors conclude that lynx were living in those places.
In his testimony to Congress, Mills explained that “follow-up snow tracking and trapping efforts are built into the study to separate actual lynx populations from transient individuals, fur farm escapees, or, as we have learned, mislabeled samples.”
Field workers are currently investigating another anomaly that turned up in the survey. Four samples, out of more than 1,200 processed, suggested lynx hair came from the Boise National Forest in Idaho and Shoshone National Forest in Wyoming. No one has reported lynx there in recent history.
Watching from the Canadian side of the border, Proctor shudders at the mess that has resulted from a violation of a research protocol. Yet, he says, the hair research itself seems coincidental to the fuss.