Eavesdropping in the alpine

If you're hiking above treeline in the Yukon, especially near a slope of tumbled boulders, keep an ear out for a high-pitched, repeated "eeeep" sound. That's the call of the collared pika.

By Claire Eamer

If you’re hiking above treeline in the Yukon, especially near a slope of tumbled boulders, keep an ear out for a high-pitched, repeated “eeeep” sound. That’s the call of the collared pika.

“Pikas are very vocal little critters,” says Sarah Trefry, who recently completed a study of pika communication. She did her research at Pika Camp, a seasonal research camp in the Ruby Range of the southwest Yukon.

Lively little balls of fur related to rabbits and hares, pikas live in small dens among the rocks of talus slopes, and spend their summers scurrying between their dens and nearby alpine meadows, building up their haypiles—caches of green vegetation.

Pikas don’t hibernate, so they’re fiercely protective of the haypiles that will get them through the winter. And with reason.

“If given the opportunity, pikas will steal from another pika’s haypile, rather than forage for their own food,” Trefry says.

“Pikas call often and repeatedly during the summer months, when they are foraging for hay, to deter their neighbours from intruding on their territory. It’s sort of like a ‘Hey, I’m here, so you stay on your own territory!’ But pikas also become very vocal when there are predators around, such as short-eared owls, ravens, or short-tailed weasels. In this context, pikas seem to be telling each other, ‘Watch out! predator near!’”

Trefry was interested in how the pikas communicate and in what else they might be listening to in their alpine world.

“Pika Camp was a great place to test questions about animal communication because there are three species of mammals living together that use alarm calls—hoary marmots, arctic ground squirrels, and collared pikas,” she says. Pikas, she discovered, make use of all of those alarm calls.

Trefry spent long summer days crouched among the boulders near Pika Camp, pointing a microphone in the direction of small, noisy mammals or taking careful notes of their responses to a variety of digitally recorded calls, both of pikas and of other animals.

“One aspect of field work that I really enjoy is observing wildlife doing its own thing, and the chance to get up close to some neat animals. For example, one day while doing behavioural observations on a pika, sitting very quiet and still, the pika came and sat on my knee for a while.”

To determine what calls the pikas pay attention to, Trefry played them calls of neighbouring pikas, more distant pikas, arctic ground squirrels, hoary marmots, and golden-crowned sparrows. Then she analyzed their responses.

She discovered that pikas are not at all interested in what sparrows might have to say. They simply ignore them. However, the other calls definitely got their attention.

When she played back the alarm calls of marmots or ground squirrels, the pikas usually raised their heads, perhaps to check for danger or to listen carefully for more calls. They reacted even more strongly to the calls of other pikas, usually moving towards the callers and sometimes answering with calls of their own.

A slightly more puzzling reaction was the tendency of some pikas, especially males, to yawn in response to the call of another pika.

“An animal would move towards the playback speakers, stop and open its mouth, with no audible sound, nor any measurable ultrasound…. Grooming of the face and whiskers often followed,” Trefry reported in an article about her research.

Yawning means different things in different animals. Dogs, for example, may yawn as a sign of fear or anxiety, Trefry says. In collared pikas, the yawn might be a ritual response to an invader in the pika’s territory.

Or there might be a more direct physical reason for yawning. American pikas use secretions from scent glands in their cheeks as part of their breeding behaviour and to mark their territories. Trefry speculates that collared pikas might do something similar. The yawning might stimulate secretions from the scent glands.

“The grooming behaviour observed following yawning would transfer secretions onto their feet, and subsequent movements around their territories would leave a scent trail.”

That explanation is still just speculative and will require more research to prove or disprove. However, Trefry’s study demonstrates clearly that pikas do more than make noise and hay as they scurry around their alpine territories. They’re also communicating with each other—and eavesdropping on the conversations of the neighbours.

For more information about pikas, contact Sarah Trefry at s.trefry@unb.ca.

This column is co-ordinated by the Northern Research Institute at Yukon College with financial support from Environment Yukon and Yukon College. The articles are archived at www.taiga.net/yourYukon.

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