Squirrels: Nature's Real Gardeners

Image of Eastern gray squirrel in Hyde Park by Monkeywing — Above: An Eastern gray squirrel buries a cache – or perhaps merely pretends to do so in a clever attempt to foil would-be nut robbers – in London’s Hyde Park. Transported to places well outside their range a century ago, the animals have adapted well to their adopted homelands. (Photo by Monkeywing) Top, featured image: A red squirrel in Bas-Saint-Laurent, Quebec, enjoys a maple seed. (Photo by Gilles Gonthier)

By Nancy Lawson

In 1749, Pennsylvania put a bounty on Eastern gray squirrels—threepence per scalp. Their crime? Eating too much corn. It wasn’t the first time humans waged war on the bushy-tailed rodents: Massachusetts had already offered fourpence.

A century later, cities along the Eastern seaboard began releasing gray squirrels into urban centers for the enjoyment of local residents, even supplying nest boxes and community-stocked feeders. Treated more like outdoor pets than wild animals, squirrels were also transported far from their native stomping grounds to cities like Seattle and London, where Eastern grays are now blamed for marginalizing other species.

Squirrels are caught between unbridled admiration and relentless persecution, reflecting our contradictory relationships with animals.

A microcosm of our contradictory relationships with animals, human-squirrel interactions have long been shortsighted. Caught between unbridled admiration by those who delight in their acrobatic ways and relentless persecution by others intent on “doing battle” with them, common tree squirrel species are sometimes subjected to draconian treatment. Though the scene of perceived seed-stealing crimes is more likely to be a birdfeeder these days than an agricultural field, the measures are still drastic; one of my friend’s relatives shoots squirrels to guard the feast he’s laid out for songbirds.

Humans can be cruel and irrational, especially when the motivation is revenge. John Griffin, director of urban wildlife solutions at the Humane Society of the U.S., has seen his share of squirrels left to die after homeowners set traps and never looked back. “There’s a real disconnection from nature that exacerbates the problem,” says Griffin, an expert in humanely evicting animals from attics, chimneys and other structures. “If you have an animal who’s a nuisance or in your house, typically it’s framed as, ‘This animal is targeting me in some way, I’ve got to solve it; I’ve got to solve it on an emergency basis’—without really understanding what’s going on.”

Making a House a Home

Image of baby squirrel in hand — Humane wildlife companies make sure to keep squirrel families together when performing evictions. Mothers bring babies to alternate den sites, which they keep on reserve in the landscape in case anything happens to the original nest. (Photo by Humane Wildlife Services)

If they can intercede before clients act on those instincts, humane wildlife companies explain that a squirrel in the attic is likely a mother seeking a safe space to raise her young. They determine where the animals entered. They remove babies, place them in a box nearby, install a one-way door and wait for the mother to move her family. Once everyone’s out, humane services seal entry points to prevent recurrence. When the call for help comes too late, they are sometimes left to pick up the pieces of botched jobs: In one case, Griffin arrived to find an illegal body-crushing trap clamped down on a squirrel who just happened to be walking by. Beyond the obvious cruelty, such approaches don’t solve the problem, targeting random animals while the squirrel family in question is still cozily ensconced in an attic.

Image of squirrels scaling a wall to get the attic — Squirrels are acrobats, able to scale walls like mini Spidermen to access nesting sites in attics. (Photo by Humane Wildlife Services)

Failure to consider animal behavior or repair structural damage creates open invitations for wildlife. Squirrels’ ingenuity knows few boundaries, and their maternal instincts are so strong they’ve been known to fight off dogs and, on rare occasions, chew through metal to get to their young. They can scale walls and squeeze through 2-inch holes. “There’s no difference to a squirrel in terms of what’s natural and what’s human-built,” says Griffin. “They’re like a house can opener.”

Stocking the Pantry

Image of Eastern gray squirrel by Joseph Palatinus — An Eastern gray squirrel works hard for his food in a suburban Chicago yard. Eastern grays can even dig through snow to find their buried treasures. Late winter can be a particularly difficult time for squirrels because food resources are scarce – another reason to tolerate and even welcome their presence at your bird feeders. (Photo by Joseph Palatinus)

Anyone dismayed by squirrelly bird feeder antics will recognize that description. But understanding more about what Wilkes University professor Michael Steele has called their “high-maintenance lifestyle” may garner sympathies of even the most frustrated squirrel detractor.

Image of Eastern fox squirrel with acorn — An Eastern fox squirrel works on an acorn in a Texas yard. Researchers have documented Eastern gray squirrels, Eastern fox squirrels, and Mexican fox squirrels excising embryos from white acorns before burying them–a food preservation method that keeps their winter supplies intact. (Photo by Ken Slade)

Unlike other squirrel species, tree squirrels don’t hibernate and must regulate food supplies all year. Research by Steele and others has documented their ability to decide which seeds are better eaten immediately and which ones can be stored. Some species can even keep fast-germinating white oak acorns from sprouting by excising embryos before burying the seeds. They remember cache sites, monitoring and relocating food throughout the season.

Image of squirrel on roof — A red squirrel in Camrose, Alberta, where the species can find plenty of its main food supply: conifer cones. Red squirrels are also excellent food preservationists, placing mushrooms on tree branches before storing them; the subsequent drying process kills insect larvae and nematodes that could otherwise destroy winter caches. (Photo by Marilylle Soveran)

“One of the big misconceptions is that their behavior just seems so random, that they’re just out there popping around,” says Steele. “And the thing [people] have to realize is that just about every minute of every day is a careful behavioral decision that they’re making in order to survive.”

Eastern gray squirrels even engage in “deceptive caching,” digging a hole and pretending to bury a seed they keep in their mouths. “That actually meets the criteria of tactical deception,” says Steele, “which was generally only thought to occur in primates.”

While creating their food caches, squirrels plant trees that feed hundreds of species. Many of those species in turn sustain others; oak trees alone support more caterpillars, the mainstay of most terrestrial baby birds’ diets, than anything else in the forest. “We suggest that the importance of tree squirrels in some biomes or ecosystems may be significant enough to elevate them to the status of keystone species,” write Steele and co-author John Koprowski in their book, North American Tree Squirrels.

The Gifts They Bring

Image of squirrel with walnut — An Eastern gray squirrel in Massachusetts finds a prized walnut. As a “scatter hoarding” species, Eastern grays bury nuts far enough away from parent trees that some will invariably sprout, eventually providing even more food and cover for wildlife. (Photo by Lorianne DiSabato)

Our backyard squirrels, then, are nature’s ultimate gardeners, returning to earth the seeds of wildlife-sustaining plants that we humans cut down. How ironic is it that animals who help birds far more than any birdfeeder could are the object of such angst among birdwatchers and gardeners? How much more fulfilling would our relationship with other species be if we remembered they all have a place in the landscape?

How ironic is it that animals who help birds far more than any birdfeeder could are the object of such angst among birdwatchers and gardeners?

Even when growing food, we don’t have to issue a bounty on squirrel heads to protect our gardens. Rock squirrels and tree squirrels have made themselves at home on Tammi Hartung’s Desert Canyon Farm in Colorado, eating birdseed and chewing through irrigation system emitters. Rather than chastise the squirrels, Hartung lets them join the feast and plants hedgerows rich in food for wildlife. Realizing the squirrels are thirsty, she places saucers of fresh water near drip lines. A hot pepper-petroleum jelly mixture slathered around emitters offers extra insurance.

Her methods are successful because she avoids jumping to conclusions, says Hartung, the author of The Wildlife-Friendly Vegetable Gardener. “Just sit for a little while and pay attention to what’s actually going on,” she advises. “Then you can figure out a better way to handle it.”

Through closer observation on my own land, I’ve learned that squirrels and other animals bring more gifts than they take away. We just have to be willing to accept them. Last spring, a friend suggested I remove the oaks, hickories and walnuts popping up in my grass and wildflower areas. Years ago, I probably would have. But now I’ve ceded some landscaping work to nature’s real gardeners, who, if only we’d let them, could eventually plant enough seeds, berries and nuts to feed us all.

Protecting Your Own Nest

Image of squirrel in tree — (Photo by Marilylle Soveran)

It’s easier to prevent squirrel entry than to perform evictions. Limit roof damage by keeping branches at least 6 feet away, recommends HSUS urban wildlife solutions director John Griffin. Cover attic side vents and seal holes at roofline intersections. Just be sure to check for animals first; if a family is inside, wait for them to leave or consult with a humane wildlife company. Avoid those that claim to humanely relocate squirrels, a method that often separates families and leaves dependent young behind. Adults also suffer a cruel fate: relocation even a short distance away is often deadly for squirrels and other animals, who may have more trouble competing for resources with their own kind and avoiding predation from others in unfamiliar territories. Get more tips on coexisting with squirrels »

This is an updated version of an article that originally appeared in the November-December 2015 issue of All Animals magazine.

For More Information

A journey through the science of squirrel behavior: Much of what we know about gray and fox squirrels comes from the research of Michael Steele and John Koprowski, who tell the story of their studies in the engaging book, North American Tree Squirrels. Since its 2001 publication, Steele has continued to make groundbreaking discoveries about squirrels and their role in oak seed dispersal, the subject of a new book in progress with the help of a grant from the National Science Foundation.

A squirrelly encyclopedia: Squirrels: The Animal Answer Guide, by Richard Thorington Jr. and Katie Ferrell, covers everything from where squirrels sleep to how they find the food they’ve buried.

Essay on the history of the Eastern gray squirrel: See The Urbanization of the Eastern Gray Squirrel in the Journal of American History for a fascinating and sometimes disturbing account of squirrel-human relationships.