Your walks through Canada's national parks aren't as nature-friendly as you think.
Even the occasional hiker on a trail is enough to ward off elk and wolves and affect the predatory balance of wildlife in a park, a study released Friday shows.
By tracking animals using GPS and measuring trail use, researchers found that just one hiker an hour caused the elk and wolves to avoid going within 50 metres of a trail. Anything over two hikers an hour kept them farther away, up to 400 metres for wolves.
The new report follows a recent one from the same lab, which showed anything more than 18 hikers a day on a trail was enough to affect the ecosystem by scaring off predators from their prey.
Researchers say the findings hold true coast-to-coast, though the most recent study was based on results from three parks in British Columbia and Alberta.
"The same situation has been seen by national parks in Canada and internationally. People everywhere should understand the role they play in the ecosystem so we can avoid unwanted effects," said Marco Musiani, a University of Calgary professor of ecosystem and public health, whose lab oversaw both studies. "It tells us that humans are not passive visitors. They actually influence ecosystems when they exceed certain levels of use. And such levels are being exceeded regularly – in certain seasons, in certain weekends – on a number of trails in national parks."
The study was carried out in Banff, Yoho and Kootenay national parks and partially funded by Parks Canada. Banff is among Canada's busiest parks, with an estimated four million visitors annually.
The busier the trail, the greater the difference in how prey and predators respond. Elk, for instance, will not be as strongly deterred by a busy trail – the animals are regularly seen in the Banff townsite itself. Wolves, however, stay far away from humans, who the study says serve as a de facto "non-consumptive" predator when on trails.
"Therefore, we're really creating refuge where it's safe for herbivores and we're effectively influencing how the system works," Prof. Musiani said. In the long run, the study warns that affecting the habitat of herbivores and predators has "undesirable consequences."
Graduate student J. Kimo Rogala, who led the study, said his goal was to help hikers and park managers understand their impact – not discourage it.
"I wanted to do this type of research so it could be used as a tool," Mr. Rogala said. "What it says is that when this level of human activity occurs [on trails] you'll start to see wildlife moving away from these areas."
Trails in national parks are typically well-managed, said Nigel Douglas of the independent Alberta Wilderness Association, but the study clearly demonstrates the impact.
"It's a tough job. They have these two mandates – of trying to manage things for ecological integrity and trying to manage things for visitors," he said. "One of the things I get from a report like this is the constant reminder that things are a lot more complicated than we appreciate."
If tightly controlled national parks are being affected by human activity, the impact in unprotected areas – with more traffic and off-road vehicles – is likely much higher, he said. "This is the effect we're seeing on relatively well-managed trails on national parks – so what are the effects on trails outside national parks?"