Amanda Kelley got into squirrel studies for the money.

"Squirrels live in trees, there's money for forestry, so that's how I got my first in," the University of Alberta biologist says with a laugh when asked why she chose to study squirrels.

It also doesn't hurt that they are easy to trap and track, she adds.

That ease in trapping has really helped Kelley in her most recent research: investigating how squirrels' personalities change as they age.

Amanda Kelley

Researcher Amanda Kelley takes a selfie with one of her test subjects - a red squirrel. (Amanda Kelley)

"Personality's a bit of an interesting thing," says Kelley, who is also the field coordinator for the Kluane Red Squirrel Project in the Yukon.

Most studies to date have ignored animal personality, she says. Researchers have only recently begun to take interest in how an animal's unique behaviours could affect their ecosystem at large.

"When we started looking at personality, we found that it was really important for a lot of things — who an animal mates with, the success of their kids, where they end up living when they grow up, all sorts of things," Kelley says.

The tricky part is how to scientifically study animal personality.

"I have what I affectionately refer to as a 'thunderdome' — and that's just a plastic white box with a clear lid," says Kelley. "I put the squirrels in there and video their behaviours."

Specifically, Kelley is looking at two traits: activity — or how much the animals move around, and aggression — which is scored by holding up a mirror in front of the squirrel and watching how they respond.

"The responses are really variable. Some of them bounce around a lot some of them sit there the whole time," Kelley says.

And the young squirrels' behaviour also changes over time, she says.

"Personality changes as squirrels grow up," Kelley says. "When they're very young, they have extreme personalities — so some are really active and aggressive, whereas others are kind of slower and not as good with confrontation."

But as they grow older, the squirrels become "conformists," she says. Measuring the same squirrel's behaviours eight months later showed the "intense" squirrels calm down and the reluctant squirrels had grown more confident.

While it's still early in her research, Kelley says her preliminary findings show the changing personality may be correlated with the younger squirrels leaving their mothers to establish their own territory. Between the two tests, they've also survived their first winter on their own.

"It's a very risky time of their lives, so behaviours can have really severe consequences," she says.

Kelley is now working on writing up her findings.