Little is known about pikas and marmots, but there is emerging evidence that climate change is going to make their survival even tougher as their high country habitat shrinks or disappears.
Pikas, small fur balls known for their signature high-pitched squeak; and marmots, a much bigger mammal with a long, shrill whistle, thrive in cold and snowy conditions in lofty places.
David Hik, a renowned biologist in the department of biological sciences at the University of Alberta, recently shared results of his long-term research project on collared pikas and hoary marmots in the Yukon.
Hik said it is still challenging to predict population dynamics of herbivores in northern mountain environments, but certainly both the timing and amount of snow is absolutely critical.
“We’ve learned that what these guys are doing is inseparable from climate systems,” he said at a Bow Valley Naturalists meeting in Banff, Feb. 23.
Hik’s presentation was the first in a series of programs planned by BVN for this year to focus on what are known High Elevation Localized Species (HELS).
Pikas and hoary marmots are found throughout alpine meadows in the mountains of Western Canada, but very little is known about their ecology and vulnerability to disturbance and environmental change.
Recent studies suggest the extent and timing of snow cover plays a critical role in determining the survival, reproductive success, behaviour, and growth of mammalian herbivores living in alpine environments.
Hik’s Yukon study site is in the Ruby Range, about 20 kilometres east of Kluane Lake on the boundary of Kluane National Park, and has been intensively studied since 1995.
The valley itself is only four square kilometres, but smaller sites are located along a 100-km transect extending all the way to Nunataks in the St. Elias Icefields and the slopes of Mt. Logan.
Hik said changes in ocean temperatures that drive the global climate system and weather patterns appear to have a “significant and measurable influence” on the survival and reproduction of these small mammals.
“In the past decade, the progressive loss of persistent snow cover that provides protection from extreme conditions can lead to population declines, at least in the Yukon, where populations of these species have been studied for the past 17 years,” said Hik.
“Unfortunately, there is almost no other information from other regions in Canada, even though marmots and pikas are widely distributed. Herbivorous mammals living on the tops of mountains are likely to be good indicators of how species might adapt – or not – to climate warming.”
As part of the project, collared pikas and hoary marmots were trapped, fitted with identification tags, measured, weighed and sexes were recorded. Some genetic work has also been done.
Over the past 17 years, scientists have noticed that populations of both collared pikas and hoary marmots in their study area have gone up and down over time.
They discovered that poor survival of pikas was associated with late snowmelt and deep snowpack, but good survival seemed related to early snowmelt and shallow snowpack.
Research indicated the litter size didn’t vary between years and the number of litters didn’t seem to change, but the timing of births seemed to change when there was late lying snow.
Hik said the average birth date in 1999 and 2000 was significantly later than other years, but there appeared to be no effect on growth and survival.
“It wasn’t limited food or predation and or mating wasn’t even an issue; they weren’t dying because they didn’t eat, but clearly they were bouncing all over the place,” he said.
“There was a lot of variation of snow and timing of snow. The huge variation could certainly account for different patterns of survival and productivity.”
Pikas spend their summers gathering and stowing vegetation in great haypiles in their homes in crevices between rocks and boulders.
Interestingly, Hik’s study also discovered that in the icefields, pikas were not strictly vegetarians.
“We found they eat the brains of dead birds. They were supplementing their diets in spring with bird brains,” he said.
As for marmots, a highly sociable species that hibernates much of the year, changes in population numbers have also been observed over the past two decades.
Hik said the timing of snowmelt is really influential on reproductive success of marmots.
“If snowmelt is delayed by a month, we lost two-thirds of the reproductive effort in that year,” he said. “Females make choices to survive themselves, rather than wean their young.”
Also, it is interesting to note that the number of times marmots arouse from their winter slumber during hibernation increases with shallower snowpack.
“If it’s a deeper snowpack, there may be fewer arousals,” he said.
Hik said marmots and pikas are reacting differently to climate changes.
“They eat the same plants, they’re living on top of each other, experiencing the same environments, but they’re not doing the same thing,” he said. “They’re doing different things at the same time in relationship to climate variability.”
Scientists say there is evidence pointing to loss of habitat as trees and shrubs move further up slopes because of rapid changes in the climate.
They have been able to reveal this through repeat photography, remote sensing and plot-based studies.
The thinking is that a 100 metre rise in tree line will lead to alpine habitat fragmentation, while a 525 metre rise will lead to alpine habitat loss.
“Eventually, this means less alpine meadows, and this means species that depend on the alpine like pikas, sheep, and marmots are going to find themselves in a bit of difficulty,” said Hik.
In Banff, BVN has launched a project to compile information on the distribution of four species that live in the high country – hoary marmot, pika, mountain goat and white-tailed ptarmigan.
BVN is asking people to keep track of their sightings of these species and record those observations on the HELS section of their website.
Parks Canada’s database for Banff, Lake Louise, Yoho and Kootenay, meanwhile, shows just 20 recorded observations of American pikas from 1978 to 2008 and 107 marmot sightings in the same period.
“When I heard about the HELS mapping by BVN, I got really excited,” said Hik. “I think this is an opportunity to try and get baseline information on the status of the species.”
