Getting to Know Central Park’s Squirrels

Editor’s Note: Squirrels are a familiar sight in Central Park, energetic and busy ambassadors to our shared greenspace. While the nature here is indeed “natural,” it takes intentional, proactive work to keep the Park a welcoming environment to wildlife like the Eastern gray squirrel. The Central Park Conservancy, including its Natural Areas, Tree Care, and Gardens teams, ensures the health and sustainability of the Park’s ecosystems and landscapes. We prioritize native plant species that nourish our wild residents, remove invasive species, and leave snags (dead or dying trees) in the woodlands—all in order to cultivate a habitat in which the Eastern gray squirrel, and many other species, can find sustenance and shelter. Although we share this space with them in our year-round care of the Park, perhaps no one is more familiar with their playful personalities than the data scientists and squirrel aficionados behind the Squirrel Census.

As anyone who has visited Central Park knows, there are a lot of squirrels therein, and the Park is big—well over 800 acres. That didn’t stop the Squirrel Census, an organization I created in 2012, from leading a count of the Eastern gray squirrels (Sciurus carolinensis) in the Park in 2018. Our six-person team clearly needed help with the endeavor, and we got it from the Central Park Conservancy, The Explorers Club, New York University, NYC Parks, a tweet from the mayor’s office, and 323 “Squirrel Sighter” volunteers.

Yes, this is real. The New York Times wrote about us, among other outlets, but even confirmation by The Gray Lady didn’t convince everyone that such an enterprise could be accomplished. Squirrels are, well, squirrelly, and small, and hard to track. They all look alike, many claim. Also: Why count squirrels?

Establishing our work on a methodology created by Vagn F. Flyger, a Danish-American biologist who many call the preeminent squirrel expert of his time, it took two weeks to perform the task and months to pore over the resulting data. Plugging the numbers into a Flyger formula, we estimated that there were, at the time of count, 2,373 squirrels in Central Park, or about 2.74 squirrels per acre (1,798 per square mile).

Based on previous counts we have performed, we determined this to be a healthy, sustainable number. That’s good news for the Central Park squirrels, because they don’t have options if living arrangements get too crowded. They’re on an island. It’s a rectangular green haven in a sea of cement, steel, and killer cars. If they cannot make it there, a squirrel version of Sinatra might sing, there isn’t anywhere else.

Because generations of these Central Park grays (and their DNA) have remained mostly untouched by their more rural Sciurus brethren, they are unique. It would be easy to make anthropomorphic jokes that they’re more citified, cultured. Maybe so. They have been forced to adapt to human cities; they have also earned a place as one of the more popular animal citizens in Central Park.

A Long, Long Time Ago…

Squirrels have been around a lot longer than us. The oldest tree-squirrel fossil, on display at the Smithsonian, is the Douglassciurus jeffersoni skeleton, a critter that lived about 36 million years ago in what is now Wyoming. Gripping a nut in its forepaws, it looks much like today’s Eastern gray. Since then, squirrels have spread around the world—and grown the squirrel family to over 285 species that are either the tree, flying, or ground variety.

The first Eastern gray squirrel caromed through the North American canopy about four million years ago. From its beginning, it took on a consequential, yin-yang role in the grand opera of nature, says Richard Simon, head of the wildlife unit for NYC Parks.

“Squirrels served as a food source for birds of prey and other carnivores, so they helped in that circle of life,” he says. “In a forest setting, they helped the forests grow by planting seeds, burying acorns.”

The Eastern gray is also built for forest survival: small, nimble, leery. The average adult ranges in length from 15 to 20 inches from head to tail and usually weighs somewhere between 0.8 and 1.3 pounds. It is diurnal; it’s up with the sun and returns to the nest at nightfall, and it’s most active a few hours after sunrise and before sunset.

An omnivorous scatter-hoarder, the Eastern gray’s days are spent foraging, eating, and caching acorns and other nuts. It also noshes on fruits, berries, insects, corn, wheat, tree bark, fungi, carrion, seeds, flower and tree buds, and sometimes bird eggs and fledglings, many of which are plentiful in Central Park.

The Eastern gray squirrel mates twice a year. It’s also smart, as one former NASA engineer can attest. And it’s surprisingly athletic. A gray squirrel can, of course, climb trees with ease. It can jump more than five times its body length, and it can run at a top speed of about 20 miles per hour—all handy attributes when evading predators that include hawks, falcons, owls, dogs, cats, wolves, foxes, coyotes, raccoons, bobcats, snakes, and of course, humans.

The Eastern gray’s tail, while impressive to look at, is not just for showing off. It contains a complex system of veins that helps keep the squirrel warm in the winter and cool in the summer. It is a communicative tool used to confuse predators about the squirrel’s size or to signal to and flirt with fellow squirrels. And it also uses it as an umbrella when it rains, for balance when traversing trees, or as an air rudder when jumping and, yes, falling. (Lucky for the Eastern gray, no matter how far it plummets it won’t reach terminal velocity, which is one reason it often survives slips from tree branches.)

Squirrels and the City

The Eastern gray was introduced into Central Park in the 1870s, part of a trend at the time to bring a bit of nature back into our sooty, crowded cities. Soon, the Eastern gray became a prerequisite resident for city parks and other urban greenspaces.

Along with the pigeon and rat, the Eastern gray is one of the few undomesticated mammals to figure out how to successfully live with us in our biggest cities.

“I call them ‘pedestrian animals,’” says Colin Jerolmack, Professor of Sociology and Environmental Studies at NYU. “The critters who have lived among people and in cities for so long that they have adapted their habits to our own, often to such an extent that they do better in cities than in their native habitat. They’re pedestrian in both senses of the word: They’re common, everyday animals (squirrels, pigeons, sparrows), and they literally walk the sidewalks.”

The Eastern gray has become an essential character in the rugged narrative of Big City life. New Yorkers can relate to its everyday willingness to get up each morning, get out in the world, and get to work, Simon suggests.

Squirrel Census Observations

Along with tallying squirrels, the 2018 Central Park Squirrel Census gathered data on general age, squirrel behavior, activities, fur color, predators in the area, communication, and other notes.

Among the findings, we confirmed that squirrels are strategically situated throughout the Park in clusters, like stars in a galaxy, with the densest constellations located in areas with thick tree canopies used for food and shelter. The area with the highest squirrel density is the Ramble, where we recorded 155 squirrel sightings in close to 10 acres (almost 15.5 squirrels per acre, or five-and-a-half times the average Park density).

Resourceful grays also hang out near entrances where trash receptacles, and perhaps the misinformed Park visitor, offer free food. Squirrels in more natural areas of the Park, including the northern third, are more likely to see humans as a threat and run from them. The large majority of Eastern grays observed in the census, however, were “indifferent” to us (as much as it hurts to admit it).

One of the more distinctive traits of the Central Park Eastern grays is seen in their varicolored fur patterns. While many people assume all Eastern grays look alike (gray), Central Park Eastern grays, like those in other New York City parks, have their own style. Six hundred and sixty-two squirrels sighted during the census were either all cinnamon or all black. Even more were a mix of colors. Some notes recorded by Squirrel Census Sighters:

• “Cinnamon face and stripes on back”
• “Blonde?”
• “Cinnamon pants and sleeves”
• “White tail tip”
• “Cinnamon oval on back”
• “Perfect mix of gray and cinnamon”
• “White ring on short tail”
• “Looked like she was wearing brown gloves”

But Why?

Many people ask us “why” we would perform a squirrel census. We have too many reasons to name here. (Our website and reports have plenty of information.) But it’s important to note that when you engage in any kind of census, you don’t just learn about the animal you’re counting; you also create a profile of—and better understand—the community or country in which it lives. Our census and all of the supplemental data we gathered, in other words, helped us perceive and appreciate Central Park—and all of its residents—in a fresh way.

On a more poetic note, when you take a moment to get out in the world and look around, you just might see something that stays with you—maybe even something that reflects the personality of the city that we call home.

Jamie Allen is the creator of the Squirrel Census, a data, science, design, and storytelling team. His writing has been published in The Paris Review, Salon, and McSweeney’s, among other notable publications. With the help of 323 volunteer Squirrel Sighters, the six-person team performed a count of Eastern grays in Central Park in October 2018. The following year, they released the Central Park Squirrel Census 2019 Report.