Group living works well for hoary marmots
Hoary marmots are not the easiest animals to study. For one they live on rocky slopes high in the mountains where the weather is forbidding for most of the year. They were also known -- until recently -- as notoriously hard animals to trap.
 |
|
Research on hoary marmots in the Ruby Range will provide new insights on these social animals.
(photo: Tim Karels)
|
To look at them, one would never guess that these roly-poly little animals would be so difficult to entice. Sometimes referred to as tundra bears because of their chunky appearance and waddling gait, hoary marmots just do not look like picky eaters.
But researchers had tried to lure them with baits ranging from peanut butter to pancakes, finally giving up in frustration when the marmots spurned them all.
Tim Karels also had problems when he first tried trapping hoary marmots in the Yukon's Ruby Range in 1999. As well as peanut butter, he tried carrots, apples, margarine, raisins, and salted oats. He even tried natural vegetation, but nothing worked.
Finally, and somewhat reluctantly, he resorted to the method used by the only person he knew who had managed to trap a hoary marmot, and it worked like a charm. Human urine turned out to be the one bait that marmots just could not resist.
"It could be the combination of nitrogen and salt in the urine that attracts them. That is my guess. It is not the most attractive bait, but you use whatever is necessary," says Karels.
Solving this one technical problem has allowed Karels to proceed with pioneering research on these animals. As well as answering questions about an animal that is abundant in alpine areas throughout northwest North America, the information might also be used to help save Vancouver Island marmots, an endangered species closely related to the hoary marmot.
David Hik, a University of Alberta professor, had the original idea for the project. While studying pikas in the Ruby Range, he noticed that even as their numbers were plummeting (see yourYukon column 194), marmots seemed to be increasing in number.
Hoary marmots are the largest members of the squirrel family, so they were an obvious research choice for Karels, who has studied arctic ground squirrels in the Kluane area for many years. Karels is now working with Hik as a post-doctoral fellow at the University of Alberta.
The researchers want to know more about the marmots' hibernation patterns, and about how young adult marmots disperse when they leave the family home. After two summers of trapping, Karels has established that there are now about 100 marmots living in the four-square-kilometre study area.
More importantly, he now knows their family trees, at least for this current generation. And with animals as social as marmots, family seems to be everything.
Marmots trundle into their winter burrows in family groups that can number as many as 11 individuals. Karels says that the young marmots benefit the most from the extra body warmth provided by the combined bundle of fur and fat. It is important both while they are hibernating, and when they make their regular wake-up calls during winter.
When hibernating, marmots lower their body temperatures to about 4 degrees Celsius, but they do not stay in this state all winter. Instead they periodically raise their body temperatures back to their normal levels of 37 degrees Celsius.
"It is sort of a misconception that hibernation means nothing but this frozen world for eight months," says Karels. "They come out of it briefly, so they have to warm up for a short period."
They go through these changes as often as every few days at the onset of winter, and less frequently later on. And being social animals, they do it all as a group, which makes the whole procedure easier for all of them, particularly for the young.
Older offspring hibernate with the family group, even when they are mature enough to head off on their own. Some research suggests that these older siblings play a key role in helping the young-of-the-year survive their first winter.
No one knows exactly why marmots go through these periodic warm-ups during hibernation. It could be a way to get rid of bodily wastes, or to release energy more effectively from their stored fats, or it might even have something to do with sleep patterns in the brain.
European researchers have collected much of this information on hibernation by surgically implanting temperature recorders into the body cavities of alpine marmots. Next summer Karels would like to take a similar approach, implanting tiny radio transmitters and temperature recorders into some of the hoary marmots.
The instruments should collect data for two years, recording winter body temperatures and summer movements. This information would help the researchers track the marmots' energy expenditures during hibernation, and where the marmots go when they leave the family home in summer.
Karels hopes that eventually this research might help explain why there seems to have been a population explosion among the Ruby Range marmots. One possibility is that their numbers rise and fall in a cycle like those of many northern animals.
It is also possible that they are -- at least temporarily -- benefiting from the same changes in climate that have been wiping out pikas in the area.
Finally, Karels hopes that his research will benefit efforts to save the Vancouver Island marmots. As there are only 36 of them left in the wild, they cannot be studied directly. But information on hoary marmots might help with efforts to reintroduce captive-bred marmots back into the wild.
For more information on this marmot study, Tim Karels can be contacted at tkarels@ualberta.ca.
