Maddie Bender: This is the 60-second science of Scientific American. This is Maddie Bender.
Compared to its more famous, furry cousin, the tree squirrel, the golden retriever ground squirrel looks a lot like a chipmunk and hibernates most of the year. Let’s talk about bird brains: the brains of ground squirrels are about the same size as the pine nuts they eat.
Therefore, according to new research, these squirrels have observable personalities, which may be surprising. But Jaclyn Aliperti noticed this as early as 2015, when she joined a project at the Gothic Rocky Mountain Biological Laboratory in Colorado. For more than 30 years, they have been there to study the behavior of golden cloak ground squirrels. To her, some squirrels look scared and shy, while others are more than happy to get in touch and eat some snacks:
Jaclyn Alipetti: I turned my head and looked for a while, and they sneaked into my bag, trying to get peanut butter. They followed me instead of me following them, and I thought, “What happened here? It should be the other way around!”
Bender: Other scientists have observed individual animals that may seem to have personalities, but no one has rigorously evaluated them to determine whether their quirks fit the definition of consistent behavior over time.
From 2016 to 2018, Alipeti asked dozens of squirrels to participate in the four-part Olympics, and evaluated the four characteristics of rodents: activity, sociality, boldness and aggressiveness. Essentially, it’s a Myers Briggs personality test on ground squirrels.
Alipeti: [laughter] It’s almost the Myers Briggs of squirrels. But I think if we say this to people, they might not take us seriously.
Bender: The two tests were performed on a stage consisting of a small wooden box with four dents on the floor. Aliperti uses GoPro cameras to track the movements of the squirrel and analyze its movements-has the squirrel surveyed the floor? Is it beauty? Or is it trying to escape, as you heard in this clip:
[Squirrel escape sounds]
In the second test, for social skills, Aliperti slipped out of the trap wall, revealing a mirror on the stage. Since squirrels have not been proven to recognize their own reflexes, the experiment allowed researchers to observe how ground squirrels treat other members of their species. Some squirrels avoid the mirror, while other squirrels approach head-on and put their noses on it. This is a common behavior between mother squirrels and their cubs.
The third test involves a researcher slowly approaching squirrels in their habitat to see how close they can get. This is a measure of the squirrel’s guts. Finally, the scientists set up harmless metal cages and used sunflower seeds or peanut butter to lure squirrels inside. After entering the trap, the squirrel’s weight triggered the latch, and then—
[Sound of trap closing]
Bender: The cage is closed. Then, a researcher monitored the squirrel’s behavior for a few minutes to assess its aggressiveness or docility, and then let it go.
In this squirrel tetraathlon, each animal performed differently, but in the three years that Aliperti observed them, their respective performances remained consistent. Importantly, ground squirrels’ personalities change with their success in the wild: squirrels that are bolder, more active, more aggressive, and social are more likely to enter high places, where they can better watch out for predators.
Aliperti said it was surprising to find links between habitat visits and social interactions on several levels. Ground squirrels are widely regarded as unsocial, and one might predict that a less social squirrel will monopolize the entry of bass through territorial behavior. On the other hand, social squirrels may have greater power in numbers:
Alipeti: We think this may be related to space sharing. Perhaps the more social squirrels gather together, they share habitats, and they overlap more in space…If they have more habitats, then they may be closer to one at any given moment, so they can Jump there and look around and see the predator before it’s too late.
Bender: Aliperti’s research was recently published in the journal Animal behavior. [Jaclyn R.Aliperti et al., Bridging animal personality with space use and resource use in a free-ranging population of an asocial ground squirrel.]
If you study the same group of squirrels for many years, you will eventually get the favorite. Aliperti said she was able to identify her by the colored dye markings applied to all squirrels each year.
Alipeti: In particular, there is a man, we call him Cross Rump, because most of the time his dye mark is just a horizontal line across his ass. He is everywhere, he has a big home, he is checking all the ladies, he will cross the street and make me have a heart attack.And, you know, try to sneak in and eat our snacks
Bender: As expected, Cross Rump achieved excellent results in the proximity test, allowing the researchers to approach him a few inches. Aliperti said she would never forget the squirrel:
Alipeti: I have to say that squirrel is my favorite. Do not play favorites. But he is.
Bender: thanks for listening. For the 60-second science of Scientific American, my name is Maddie Bender.
[The above text is a transcript of this podcast.]