Uptown Squirrel

Roman Mars:
This is 99% Invisible. I’m Roman Mars.

Roman Mars:
This past fall, 200 people gathered at The Explorer’s Club in New York City. The building was once a clubhouse to famed naturalists and explorers. Now it’s an archive of ephemera and rarities from pioneering expeditions, from treks to the world’s tallest mountains, the North Pole and the Moon. Woolly mammoth tusks frame a fireplace. A menacing polar bear towers near the landing with claws at the ready. And a cheetah, rumored to have been shot by Teddy Roosevelt, sits on a plinth just upstairs.

Kaitlyn Schwalje:
The gathering was in honor of a new expedition, one in search not of a single animal but of thousands.

Roman Mars:
That’s reporter Kaitlyn Schwalje.

Kaitlyn Schwalje:
The club was hosting a biological census. An ecological survey so difficult, so complicated, so taxing that it had never been attempted before and may never be attempted again.

Jamie Allen:
It is a really big project. I don’t think we’ve ever been involved in a project of this scope in our lives. It’s like moving a small little army around.

Kaitlyn Schwalje:
This is Jamie Allen. The census was his idea, and when he started it was a small operation.

Roman Mars:
But now Jamie is merely the tip of a vast pyramid of census-related personnel, including a logistics chief, a chief cartographer, a veterinarian, an epidemiologist, a specialist from the Fish and Wildlife Service, and of course a web team.

Kaitlyn Schwalje:
And that’s just the core staff. Below them are the foot soldiers, the volunteers who must go out into the field and do the actual counting.

Jamie Allen:
Three hundred-plus volunteers, counting 700 hectares, 100 meter by 100 meter, and 3,000-plus sheets of paper that we have to … It’s, yeah.

Kaitlyn Schwalje:
A vast filing system, multiple offices, and a team of hundreds, all for the sake of answering one question.

Jamie Allen:
I want to know how many squirrels are in Central Park.

Roman Mars:
Squirrels. They’re counting squirrels.

Stu:
Date – October 14, 2018. Time – 5:26.

Kaitlyn Schwalje:
On a chilly Sunday evening, I’m following Stu, one of the Central Park census volunteers, around the park’s northern end. We’re on the hunt for eastern grey squirrels, which is like THE squirrel. It’s what you’ll find in just about any American city, but especially Central Park.

Stu:
We need to be on this path down here.

Kaitlyn Schwalje:
Okay, how we do get in there?

Stu:
Well, I’ll pretend you’re not here, right? I just keep doing it?

Kaitlyn Schwalje:
Yeah, yeah.

Stu:
All right, cool.

Kaitlyn Schwalje:
Following his lead, we head off the path, over fences and through tall brush. My face is going to be covered in poison ivy soon.

Stu:
Oh God, without a doubt.

Kaitlyn Schwalje:
We’re slowly making our way to his designated area, hectare 38E.

Roman Mars:
Hectares are plots of land that measure a little less than two and a half acres each. The job of a census volunteer is to count all the squirrels they can find within their assigned hectares, and only their assigned hectares.

Kaitlyn Schwalje:
Although this doesn’t stop Stu from getting incredibly excited by every squirrel he sees.

Stu:
Oh look, there’s a squirrel! I can’t count you, buddy. You’re not in my hectare. Go on. Back. See you later.

Roman Mars:
After every hectare in the park has been surveyed, all the data will get plugged into a wildlife counting formula popularized by the great mid-century Danish-American squirrel biologist, Vaughn Fleeger. The formula will account for squirrels that were double-counted and ones no one managed to find, and then finally spit out a number that the world has been waiting for – the squirrel abundance number – the total population of eastern grey squirrels in Central Park, give or take.

Kaitlyn Schwalje:
At which point, you would be totally justified in asking, as many do, what precisely is the point in knowing the squirrel abundance number?

Jamie Allen:
What they’re saying is like, “You’re counting squirrels?”. Squirrels have a specific context in people’s minds, and it’s to be ignored. It’s assumed, I think, that because they’re so common, we know everything we need to know about squirrels, but the opposite’s true.

Roman Mars:
The very fact that no one has bothered to do a Central Park squirrel census before to gather this most basic of data points about one of the most common animals in our landscape reveals a kind of societal blind spot we have in regard to squirrels.

Kaitlyn Schwalje:
For a long time now, we’ve taken them for granted, including the story of where all these squirrels came from.

Roman Mars:
The squirrels we see in our cities and towns are so everyday, so ubiquitous, so just there, that it’s easy to assume they’ve always been there. But the truth is, they haven’t.

Etienne Benson:
Mid-19th century, you could walk through a place like Boston or Philadelphia or Manhattan and you would not see a single squirrel.

Kaitlyn Schwalje:
This is Etienne Benson. He’s a historian of Environmental Science at the University of Pennsylvania, and he says the cities of the early 19th century were effectively squirrel-less.

Roman Mars:
These were animals you could only see if you left the city.

Etienne Benson:
And then even perhaps left the farm and went deep into the woods, and it was only when you went deep into the woods that you would have the chance to see something like a squirrel.

Roman Mars:
In fact, squirrels were considered so elusive, the very wealthy liked to keep them as exotic pets. In 1856, an article in The New York Times described how one such pet escaped from its owner’s home in Manhattan. And when it was discovered in a tree, a crowd of people gathered in amazement, trying to lure it down. Eventually the crowd grew so large and rowdy that the police had to forcibly disperse it.

Kaitlyn Schwalje:
So how did these eastern grey squirrels, these reclusive woodland creatures, make their way into our urban spaces? Well, for starters, says Etienne, they didn’t, at least not on their own.

Etienne Benson:
What was so fascinating to me was to find out that they had been intentionally introduced.

Roman Mars:
The squirrels that we all take for granted as we walk through the park or on our way to the gym or the office are only there because we put them there. They were deliberately brought into cities and fed and sheltered.

Kaitlyn Schwalje:
The first city that we know of to introduce squirrels was Philadelphia in 1847. Like many East Coast cities of the mid-19th century, it was already a highly urban environment. People yearned for a taste of the wilderness, that the squirrel would seem to embody.

Etienne Benson:
They were captured in the wilderness, brought into the city, and placed on a single tree, almost as if they were animals in a menagerie or a zoo.

Roman Mars:
The tree was in the middle of a small public square, and it was equipped with a wooden shelter and a fence, so the squirrels could stay safe from the elements and any would-be predators in their little squirrel home.

Kaitlyn Schwalje:
A few other cities, like Boston, replicated this model, and at first the number of squirrels was teeny tiny. Philadelphia started out with only three.

Roman Mars:
Think of it as a trial run.

Kaitlyn Schwalje:
Only this first trial run, it went terribly.

Etienne Benson:
When I started working on this topic, I thought okay, you introduce a few squirrels into an urban park, in a few years you’re going to have thousands of squirrels. No problem. But at the very beginning, they were essentially incapable of surviving.

Kaitlyn Schwalje:
The cities of the 19th century just didn’t have the kind of large parks and extensive tree cover we see today.

Etienne Benson:
When you thought about urban landscapes, they were very unfriendly to an animal that required trees for food.

Roman Mars:
In the classic storybook image of a squirrel, it’s always clutching an acorn. And that’s basically true. A wild squirrel requires deciduous nut-bearing plants, such as oak trees, in order to survive.

Kaitlyn Schwalje:
Without trees, the city had to provide for the squirrels. But the squirrel feed often proved to be either insufficient or nutritionally worthless, so those first squirrels either died off, were killed, or were adopted as pets.

Roman Mars:
In 1855, a reporter for the Boston Evening Transcript described the introduction of squirrels as “an absurd and reprehensible experiment.” All of which raises a question.

Gabriel Willow:
Why are there now squirrels everywhere in American cities? I think it’s more a model of “If you build it, they will come.”

Kaitlyn Schwalje:
Gabriel Willow is a naturalist who specializes in animal species that live in urban environments.

Gabriel Willow:
I study nature and educate people about the natural world, specifically in New York City.

Kaitlyn Schwalje:
And he says that in the late 19th century, green spaces like New York’s were undergoing a transformation. Areas of open land, once multi-purpose fields used for everything from cattle grazing to slaughterhouses and militia training, were being transformed into spaces of leisure. And by the 1870s, city dwellers were leaving behind small busy squares in favor of large idyllic parks.

Roman Mars:
And although they were designed for people, these new urban oases just might be the best thing to ever happen to the eastern grey squirrel.

Kaitlyn Schwalje:
Because the parks weren’t just big. They were also designed to mimic the natural world. Take Central Park and Prospect Park in New York, for example, both designed by Calvert Vaux and Frederick Law Olmstead.

Gabriel Willow:
They were working with the existing geology and the hydrology. They took naturally existing small ponds or marshy areas and made lakes out of them.

Kaitlyn Schwalje:
They also chose to keep the area’s dramatic rocky outcroppings instead of blasting them away, as had been done with the rest of the city’s grid.

Gabriel Willow:
And so they were working with certain natural elements.

Roman Mars:
These natural parks were filled with hedges and lakes and streams and lots and lots of trees, including, to the great fortune of squirrels everywhere, oak trees.

Gabriel Willow:
Red oak is very common. White oak is very common. Pin oak is very common. There’s a lot of acorns around.

Kaitlyn Schwalje:
Everything a would-be squirrel resident might want or need.

Roman Mars:
And it was in this oak-dotted acorn-strewn landscape in Central Park in 1877 that a handful of eastern grey squirrels were introduced for a second trial run.

Gabriel Willow:
And it was in that landscape that these squirrels virtually exploded in population.

Roman Mars:
By the turn of the century, what had started as just a few dozen squirrels now numbered in the … actually, this is around the time that people just stopped counting.

Kaitlyn Schwalje:
I mean, how could you, with so many squirrels running around? Guesses range from the high hundreds to over 5,000. In Central Park and beyond, squirrels became as commonplace as fire hydrants and telephone poles and all the other new-found accessories of the urban landscape.

Roman Mars:
And as this new approach to urban parklands spread to other cities, so did the idea of populating them with squirrels.

Kaitlyn Schwalje:
Eastern grey squirrels were introduced again to places like Philadelphia and Boston and West Coast cities like Seattle, Vancouver, and San Francisco. Eastern greys were also introduced overseas, to England, Italy, and South Africa.

Roman Mars:
And it wasn’t just the oak trees in these newly lush environments that were providing sustenance for the squirrels. At the time, people considered it their moral duty to feed them.

Gabriel Willow:
Up until the early 20th century, the dominant way of understanding the proper relationship between humans and animals in the city is centered on charity. It’s centered on the idea that humans have an obligation, a responsibility to create a friendly welcoming environment for certain kinds of animals to flourish.

Roman Mars:
The ideal city was one that provided a home for good animals and banished the bad.

Gabriel Willow:
If you go back even and read John James Audubon’s account of bird species, he might talk about the bloodthirsty hawk or the wily raven, and so people used to shoot hawks and falcons and eagles and other birds of prey, because they’re predators, because they would eat other animals. People thought, “Oh, they’re just mean.”

Kaitlyn Schwalje:
Whereas other animals like pigeons and, of course, squirrels were considered peaceful. More than that, they interacted with humans. The sight of an undomesticated animal not only approaching you but effectively communicating with you by soliciting food was a sign of its civilized nature, so it was only proper that you should feed them.

Roman Mars:
Historians would later give these wild animals and the residents who brought them into the city a name: the more-than-human community.

Gabriel Willow:
The idea was to create a kind of, well you might even call it a kind of fantasy world, in which every animal that is in the city is kind of living peacefully with the others at the indulgence of the humans that run the place.

Kaitlyn Schwalje:
Thanks to the more-than-human community model, urban squirrels lived large for decades, nuts, trees, and humans feeding them extra food and killing off all their predators. They had it made.

Gabriel Willow:
And in the case of New Haven, for example, there’s even an article that I found that describes them as becoming so obese that they began to fall from the trees.

Kaitlyn Schwalje:
As the 19th century led into the 20th, and the squirrels were busy spreading out into suburban attics and college campuses, no one stopped to wonder if there could be such a thing as too many squirrels.

Roman Mars:
But as hard as it is to admit, there is now evidence to suggest there might actually be too many.

Matthew Harper:
There is an ongoing attack against the power grid, and it’s being led by squirrels.

Kaitlyn Schwalje:
Matthew Harper is an information security expert with 20 years of experience, and he says when it comes to threats to the U.S. power network – forget terrorism, forget Russian hackers.

Matthew Harper:
In the case of the utility infrastructure, it’s the humble squirrel that’s causing most of the issues.

Roman Mars:
By some estimates, one out of every five power outages in the United States are squirrel-related.

Kaitlyn Schwalje:
To be fair to the squirrels, they really start out with the best of intentions. Squirrels need to build nests, and they usually build those nests in trees, but they also build them in anything that looks like a tree, like utility poles or transformers. And like all rodents, a squirrel’s incisor teeth never stop growing, so they have to chew to keep them filed down. They mostly chew bark and branches and nuts, but they also chew things like power cables. So inevitably, some unlucky squirrel will gnaw through the insulation of a power line or step on two exposed wires at the same time and …

Roman Mars:
Oh.

Kaitlyn Schwalje:
… killing the squirrel and shorting the system.

Roman Mars:
To keep track of all those system shorts, Matthew runs a website called “Cyber Squirrel One”.

Matthew Harper:
Which is a website which tracks squirrel activities and attacks against the power grid.

Kaitlyn Schwalje:
And yes, this is real. Cyber Squirrel One consists of a big map marking the largest power outages caused by squirrels in the past 30 years. Pick a year and you can find hundreds of pins indicating squirrel incidents, splayed out across the Lower 48 and Canada.

Roman Mars:
There’s a drop-down menu if you want to see outages caused by other animals, but don’t bother. When it comes to power problems, it’s mostly just squirrels.

Kaitlyn Schwalje:
Can you give me some examples of squirrel-related power outages?

Matthew Harper:
I’m just pulling it up now. Squirrel … here we go. Last year, in 2018, a college in California actually ended up having to cancel classes.

Roman Mars:
Then in November of 2018, a single roving squirrel knocked out three substations in upstate New York, causing a string of power outages for more than 12,000 people.

Kaitlyn Schwalje:
That same month, another squirrel took out a polling station in Virginia on the day of the presidential election.

Roman Mars:
Then in December, a squirrel cut the power of an entire shopping mall in South Carolina one week before Christmas.

Matthew Harper:
A particular case in Canada back in April of 2009 impacted 55,000 people.

Kaitlyn Schwalje:
And those are just the big ones. In Austin, Texas, squirrels were responsible for over 400 separate outages in 2015 alone.