Dung ho
Scat-sniffers use new methods to evaluate stress of Yellowstone wildlife - without adding to it
Story and photos by MICHAEL MILSTEIN
Gazette Wyoming Bureau
YELLOWSTONE NATIONAL PARK, Wyo. - Amanda Hardy bends down, grabs a chunk of yellow snow off the path through Yellowstone National Park's Upper Geyser Basin and sniffs it.

Elk urine smells sweet, she notes.

Bison urine -- well, that's another matter.

"You'd be surprised," Amanda Hardy says while on a circuit through the geyser basin early on this winter morning. "It's a very obvious difference."

A difference that most people would not be very interested in discerning. But one that Hardy, a Montana State University graduate student, has gotten to know all too well in the course of research now attempting to measure stress in Yellowstone Park wildlife, without adding to that stress.

Hardy, in fact, is collecting not only urine that stains the snow, but also bison and elk dung which, she adds, "is really starting to pile up" back in her storage room.

Eventually she will sort through those piles - probably numbering in the thousands by the time she is through - and then, in the laboratory, analyze them for hormones that reflect stress in animals just as a pulse of adrenaline through the veins usually signals stress in humans. By tying stress hormone levels to the spots where she collected the samples, she hopes to tell whether snowmobile and other human traffic along roads and trails disturbs the wildlife that often grazes placidly nearby.

Amanda Hardy, a student at Montana State University, collects bison dung for a study on wildlife stress.

"A lot of us don't show it when we're stressed but yet it affects us," said Robert Garrott, a Montana State professor of wildlife ecology and Hardy's advisor. "This is our best shot at providing some tenable evidence of whether there is stress in these wildlife populations."

It's a novel means of studying stress in wildlife that does not require capturing the animals for examination or blood samples - an action that's is not only laborious and expensive, but also stresses animals further, making it impossible to tell whether or not they were stressed to begin with.

"You can go out there and, without bothering the animal, get a sense of the conditions that are affecting it," said Scott Creel, a professor of biology at Montana State who is helping Hardy apply the method in Yellowstone.

Bird researchers have long used the same method and Creel has used it to study stress within the social hierarchy of wild dogs in Africa. It was not the lower-ranking animals that constantly got beat up on that showed the most stress, he found, but the highest ranking animals that were constantly defending their foothold at the top of the totem pole.

Another Montana State graduate student last year finished similar research that had him collecting droppings of bighorn sheep in the northern reaches of Yellowstone and analyzing them for stress-hormones. His conclusions countered the common assumption that wildlife endures the most stress in the winter, when animals would seem to have a harder time eking out a living. Instead, he instead found the highest stress-hormone levels in droppings from the fall rut, when rams compete for ewes by bashing curled horns against each other.

"The stress patterns, he determined, had more to do with the breeding pattern than with anything else, such as environmental conditions," Creel said.

Hardy's research extends beyond just scooping poop. In more general terms, she wants to assess the reaction of Yellowstone wildlife to winter recreation and compare her findings with the results of a similar study about 20 years ago in Yellowstone by Keith Aune, now a Montana Department of Fish, Wildlife and Parks biologist.

"We have two or two-and-a-half times the number of people in Yellowstone now than we did then and it's important to know how that's affecting the wildlife," says Hardy, now in the first year of her two-year project.

Nearly every day during the winter season she snowmobiles given stretches of park roads along the Madison and Firehole River valleys and walks specific foot trails, noting the presence of wildlife including bison, elk, moose, coyotes, swans, eagles and - on the rare occasions when they're visible - wolves. She uses an electronic rangefinder to measure their distance from the nearest roads and trails and then records their reactions to her presence or other human passers-by, keeping track of whether they walk or run away or simply stay put.

"Since he looked at us and then walked away, I'd call that an 'ambled away' response," she says as a cow elk sidles away from the trail.

Bison in general seem less skittish than elk, although animals may react differently depending on where they are and what disturbances they have encountered previously. People appear to bother wildlife less while walking on trails in popular places such as the Upper Geyser Basin, where animals expect human traffic, than they would wandering into an area without trails where wildlife may be less familiar with people.

Amanda Hardy records the reactions of elk to people who where walking Geyser Basin path recently.

It's inevitable that people and wildlife run into each other more often in winter, when grazing wildlife moves to lower elevations, where people also like to spend their time.

"We've put our roads in some incredible winter habitat - in the thermal areas and along the rivers," Hardy says. "If the animals stay at lower elevations, they're going to run into more people and they're going to have to tolerate more stressed."

She stops along the Upper Geyser Basin trail and uses a silver spoon to scoop up a sample of what appears to be relatively fresh bison dung and caps it inside a plastic test tube, noting the time and place of collection. Dung more than a couple of hours old, it turns out, freezes solid and will not easily yield a small sample.

Later analysis of Hardy's sample may tell her whether the bison that left its calling card along this trail was under more than the normal winter stress. By comparing its stress levels to those reflected in dung she collects from untrammeled parts of the park, she may then finally draw some conclusions about how much stress trails and the people they convey inject into Yellowstone's winter wildlife.

"Even if we see no difference in the distribution or abundance of animals between 20 years ago and now, they still could be under much more stress," Garrott says. "You can't go up and ask them how much stress they're under, so you have to come up with more inventive ways."