There are a lot of weird squirrel stories floating around out
there. These nut-crazed little critters have been spotted canoodling car engines and
casually snacking on discarded egg rolls.
There’s little squirrels won’t sink their teeth into—and their taste for
electrical wiring has infamously triggered citywide power outages.
Squirrels have even sparked an international rivalry through the color of their
fur alone: For years, five North American towns have been vying to be hailed as
the “White Squirrel Capital of the World” (the
title is supposedly held by Olney, Illinois). But that shortlist of shenanigans
is just the tip of the bushy-tailed iceberg. Here are six stupendous snippets
of squirrel science to help you celebrate squirrels today and every day.
1. Tree squirrels might give investment
bankers a run for their money.
The
moment a squirrel first encounters a tasty morsel of food, it has to make an
important decision: Is it better to eat this now, or will it be more valuable
in the future? A lot goes into answering that question, says Amanda
Robin, who studies squirrel behavior at the University of
California, Los Angeles.
Depending
on the season, food might be scarce, making the prospect of a little nosh extra
appealing. The nut itself could be highly perishable, and not worth a laborious
dig. Or there could be lurkers nearby, waiting to poach a hastily buried treat.
Many squirrel species make a ritual out of hoarding snacks—not unlike us
humans. These rodents may not be ticking items off a grocery list or stashing
leftovers in a refrigerator, but their food-storing strategies are no less
sophisticated.
Recent work from a research group led
by Lucia
Jacobs, a behavioral biologist and squirrel expert at the University
of California, has shown that fox squirrels (Sciurus niger), arboreal squirrels native
to the eastern half of North America, will cache anywhere from 3,000 to 10,000
nuts each year. And the stockpiling isn’t done willy-nilly: The squirrels
meticulously categorize their treats by source, variety, quality, and even
preference as they bury them in various locales.
“Even
if you give squirrels a random series of nuts, they will put the almonds here,
but the hazelnuts there,” Jacobs says. This technique, called
“chunking,” essentially bins important bits of information into manageable
blocks, and is thought to help squirrels keep track of their yearly inventory.
It’s the same mnemonic device that makes a phone number easier to remember when
it’s written out as 867-5309 rather than 8675309.
And that’s only part of the squirrel sorting scheme: When they
chance upon larger, more valuable nuts, squirrels will also venture farther from
foraging sites before settling down to dig. The idea is that more far-flung
locales might be tougher for competitor squirrels to find and pillage. Jacobs
likens the process to investment banking, with each new find triggering a fresh
round of caching calculus. The more precious a food item, the more important it
is to stow it away with care. In other words: have nut, will travel. “These are
economic decisions,” Jacobs says. “They just want to minimize that risk-return
ratio.”
2. With so many nuts to keep track of, squirrels need
astoundingly good memories—and oh, do they deliver.
Once a squirrel learns a trick, it won’t hesitate to use it again
and again. It’s a lesson learned the hard way by certain homeowners, who pray
in vain that the next screen door
or bird feeder won’t be torn to shreds.
In 2017, Pizza Ka Yee Chow, a squirrel researcher at
Hokkaido University in Japan, put this mental longevity to the test with a
group (or scurry) of eastern gray squirrels (Sciurus carolinensis),
which are native to the eastern half of the United States and southeastern
pockets of Canada. Chow presented her squirrels with a tricky task: pressing
levers to access big, juicy hazelnuts. The critters quickly finagled their way
through, and Chow took the puzzle away. But even after nearly two years had
passed, the same squirrels, which hadn’t seen the contraption in the interim,
still knew how to nab the nuts.
They even proved handy when offered a modified puzzle that also
relied on levers, but looked completely different. After a brief moment of
hesitation, the squirrels realized that even with this new challenge, the same
logic applied. Considering that 10 years old is a ripe old age for your
garden-variety tree squirrel, a 22-month memory ain’t too shabby. “Their memory
is just excellent,” Chow says. “It’s really amazing.”
3. Squirrels are marvelously mischievous.
Stop a dog on the street, and chances are it has a bone to pick
with a squirrel. These critters are known to tease and deceive—and their
penchant for mischief truly knows no bounds. Many of Chow’s experiments have
been at least partially foiled by roving bands of squirrel saboteurs. “They’ve
bitten off the screws and nails on our puzzle boxes,” she says. “And they’ve destroyed
some of our cameras: They’ll bite off all the buttons… and then I have to use a
pencil to get at the start and stop record buttons.” And, Chow adds, as the
squirrels fiddle with the equipment, they end up taking a lot of selfies. That
last one sounds funny—but those glamour shots can get in the way of recording
real data.
Even amongst their own kind, squirrels are master manipulators.
When eastern gray squirrels forage in the presence of others, they’ll sometimes
engage in what’s called deceptive caching:
If it senses a hungry interloper, a squirrel will fake the act of burying a
seed, all the while keeping the true prize tucked away in its mouth. A squirrel
can get pretty elaborate with the ruse, making a big show of packing the hole
with soil and leaf material, before bounding off to deposit the actual seed
elsewhere. The second squirrel, of course, raids the decoy only to be
disappointed. “Up until the point where we found it in squirrels, this kind of
tactical deception was thought to only occur in primates,” says Michael Steele,
an evolutionary biologist and squirrel expert at Wilkes University. “To
discover it in [what people consider] a lowly rodent was pretty exciting.”
According to Chow, squirrels are so clever that, in theory, we
could probably get these tiny titans of trickery to use their powers for good
(à la these trained crows that
are solving France’s litter problem one theme park at a time). But that doesn’t
mean we’ll necessarily be seeing recycling rodents in our near future. “They’re
so impatient,” Chow says with a laugh. “They’re just like, ‘Give me the nuts!!’”
4.
Squirrel speak is all kinds of complicated.
Squirrel chatter might sound like a blur of nonsense, but that
couldn’t be farther from the truth. Within that fast-paced gobbledygook is
actually an intricate repertoire of vocalizations that—depending on the
species—might involve anything from come-hither calls to signaling the presence of a predator.
Even arboreal squirrels, which tend to be fairly solitary
creatures, will still raise the alarm when
threatened by a passing hawk or a particularly ornery dog. And many of these
sounds have impossibly delightful, onomatopoeic names: The “kuk” is short, low,
and repetitive—the standard scolding you’d get from a disgruntled squirrel
that’s recently been driven up a tree. The “quaa” is higher and more
protracted, while the third sound, the moan, is even shriller and more
ululating.
And it seems squirrel body language is just as important. These
rodents’ fluffiest appendages often
offer the most tell-tail signs of danger. Two common tail movements are the
twitch—which looks something like a shudder—and the flag, which engages the
tail in a rhythmic whipping motion, almost like a revolving dough hook. Combined
with a stern flick of the tail, a reproachful chitter from a squirrel might
portend the approach of one type of predator over another. Scientists are still hard at work deciphering
the squirrelly code—but while some progress has been made, much of the jargon
has proved a tough nut to crack. Say quaat?
5. Squirrel sashays and shimmies could someday inspire
new-and-improved search and rescue technology.
Though not all squirrels are entirely aerodynamic, for those
that live amongst the trees, their day-to-day movements can put the best Cirque
du Soleil shows to shame. “They’re so agile, leaping from tree to tree,” Chow
says. “They’re like little monkeys.” Chow recalls seeing a tree squirrel on one
of her first trips to England and being struck by its agility and flexibility.
“The squirrel was very goal-oriented,” she says. “It made me want to understand
how they maneuver in this world.”
They may pale in comparison to their flying squirrel relatives,
but even tree squirrels are equipped with extraordinary anatomical adaptations
that enable them to clear ten-foot gaps between branches and stabilize on
uneven surfaces. Gray squirrels’ hind legs, for instance, are exceptionally powerful,
packed with muscles that can propel their light bodies forward over large
distances. They’re also equipped with hyper-mobile ankles, allowing them to
rotate their paws and grip onto surfaces in nearly any orientation. “Their
ability to navigate through trees and balance so well is kind of a superpower,”
Robin, the UCLA researcher, says. “At least, it’s one that I don’t have.”
These aerodynamic feats are reason enough to give squirrels
their due. But a team of researchers led by Robert Full at the University of
California, Berkeley is putting their appreciation to work in pursuit of even
loftier goals. By studying how squirrels move
through space, Full and his colleagues are figuring out how to build
bio-inspired robots that might power the search and rescue operations of the
future.
A Squirrel I Call Rocky
6.
Sometimes, it seems like squirrels are everywhere. You’re
not wrong (unless you’re in Antarctica).
To date, there have been nearly 300 species of squirrels
discovered worldwide. And these globe-trotting goobers come in all shapes and
sizes, ranging from the aptly named African pygmy squirrel (Myosciurus pumilio),
which runs just five inches from nose to tail, to the glorious, technicolor
Malabar giant squirrel (Ratufa indica),
whose three-foot-long body can be seen soaring through the lush green canopies
of Indian forests.
These raucous rodents are native to every continent, with the
notable exceptions of Antarctica and Australia (though due to the deliberate introduction of
two species in the late 19th and early 20th century, the outback is technically
no longer squirrel-free). But travel far back enough along the squirrel family
tree, and you’ll find that squirrels appear to have originated in just one
place: North America.
“They evolved here—they’re ours,” Jacobs, the UC Berkeley behavioral biologist,
says. “Then they spread all over the world.”
For better or worse, squirrels are here to stay. You don’t get
to be one of the most successful invasive species on the planet without some
serious know-how… or without stepping on a few toes along the way. At the end
of the day, though, whether squirrels have wriggled their way into your bird
feeder or your heart, they’re worthy of respect—grudging though it might
sometimes be.
-Katherine J. Wu
“Six Stupendous Reasons to Appreciate the Heck Out of
Squirrels: Take a deep dive
into the world of these surprisingly brainy, aerodynamic, nut-crazed critters”
PBS/Nova
My Squirrel-Proof Bird Feeder
