Yellowstone Wildlife Study Raises More Questions Than It Answers

A long-awaited study on the impact of snowmobile traffic in Yellowstone National Park on wildlife has finally been released...some five months after it was authored.
Yellbison A bit surprisingly, the report says responses by wildlife "to over-snow vehicles were relatively infrequent, short in duration, and of minor to moderate intensity." More surprisingly, it adds that "the debate regarding the effects of motorized recreation on wildlife is largely a social issue as opposed to a wildlife management issue."
Unfortunately, the report raises more questions than it answers and doesn't seem to instill confidence if it's trying to present long-term conclusions based on short-term data.

The study is based on data collected from December 9, 2004, through March 25, 2005. During that period, the researchers monitored more than 2,100 interactions between wildlife -- either bison, elk or trumpeter swans -- and over-the-snow vehicles.
In arriving at their conclusion that the animals' responses were "relatively infrequent, short in duration, and of minor to moderate intensity," the researchers said that more than 81 percent of the animals were judged to have no apparent response to the traffic or quickly resumed what they were doing.
But let's turn the numbers around for a moment. One might also say that nearly 20 percent of the wildlife observed showed varying signs of disturbance -- they either reacted with a show of attention or alarm, by moving away, by outright flight, or by putting up a fight.
In a national park where managers are supposed to minimize impacts on animals, doesn't it seem significant when nearly 20 percent of the wildlife is disturbed to some extent by over-the-snow traffic?
"It's disturbing to see these findings largely dismissed, that 'it's not a wildlife management issue,'" Amy McNamara, the national parks program director for the Greater Yellowstone Coalition, told me after wading through the 59-page report. "There seems to be an effort to recast the data and say that over-snow traffic is causing 'relatively infrequent' impacts to wildlife, when in fact the impacts remain all too frequent."
Also to be considered when reviewing the report is that the data were collected during the winter of 2004-05 when daily snowmobile traffic was less than half of the allowable limit of 720 machines a day. With that in mind, can these results be satisfactorily extrapolated to say that wildlife conflicts aren't going to be significant enough to equate to a wildlife management issue?
Keep in mind, too, that last winter was relatively mild. As the researchers point out in their paper, the 2004-05 winter's snowpack was 20 percent below average, a significant point that not only led to reduced snowmobile traffic throughout the winter but also made life a bit easier for wildlife.
What happens during a normal or heavy snow year when deep snows lead bison and elk onto the groomed roadways that could, under the current proposal, be traveled by as many as 720 snowmobiles a day?
Perhaps also to be recalled is the Supplemental Environmental Impact Statement the Bush administration ordered back in 2003. In that lengthy document the preparers pointed out that:

"Winter recreation activities take place during the season when animals are stressed by climate and food shortages. Disturbance or harassment of wildlife during this sensitive time can have a negative effect on individual animals and, in some cases, populations as a whole."

Further, the document noted, it's not always easy to tell when animals are being disturbed.
Bisonsnowcoach While the latest report on snowmobile impacts on wildlife suggests that bison and elk have become "habituated somewhat to motorized recreation," the 2003 SEIS states that, "because many of these responses are difficult to detect, animals that may appear unaffected by human activities may nonetheless be suffering from adverse effects. ... Habituation may occur when flight or displacement are not possible (e.g., in critical or limited winter range, during severe winters when the snowpack is deep, or when the weakened physical state of the animal precludes it.)
"Although habituated ungulates may fail to exhibit overt behavioral responses, research has shown that physiological responses, including an increase in heart rates, may occur and can result in high energy expenditures. Increases in energy expenditures during the stressful winter period are considered deleterious to the overall physical condition of the animal."
That very same 2003 report concluded that if snowmobile use were allowed to continue in Yellowstone, "risks associated with harassment and displacement would increase, and physiological stress responses would rise due to higher traffic volumes."
There's one other question that needs to be asked. The cover page of the report carries a date of July 15, 2005. What transpired in the ensuing five months before it was finely released?
Unfortunately, I couldn't reach any of the authors of the latest report to run my questions by them before posting this. But I'll keep trying.

(Photos courtesy of Yellowstone National Park)