I think the hardest part of squirrel life, at least for the males, must be finding a mate. That’s because there are between five and twenty male squirrels for every female. Moreover, that one female is only receptive to males twice a year for a few hours at a time. The males go into a fevered mania during that breeding period, monitoring the females and then joining in daylong contests for their affections. Researchers have seen as many as thirty-three males participating in these competitions. These mating bouts look, Koprowski and Steele write, like “pure and unadulterated chaos.”
The males fight each other for position, often doing serious damage with their powerful incisors and sharp claws. The dominant male then advances on the female. But the female usually has her own ideas and sprints away. The males give chase in single file. If they lose track of her, mayhem descends. They dash back and forth across the female’s territory, chirping in what sounds like a high-pitched sneeze. They will chase, with amorous intent, anything that moves. Researchers have seen frenzied males pursue blue jays, rabbits, crows, and, once, a softball.
A female may initiate these chases for her own safety, because it’s dangerous to mate in front of a lust-crazed mob. Attackers disrupt 20 percent of mating attempts, sometimes knocking the pair out of the tree. Usually the female stops in a safe location (i.e., close to the ground) and mates with the first male to reach her after a chase. If she’s managed to outrun them all, she calls out until a male finds her. The male guards the female for about twenty minutes after mating, but then the maneuvers begin again, and the whole circus can recur several times before the end of the day.
The fall breeding season is hard on males. They come out the other side injured and skinny. As Steele and Koprowski write, “Nothing demonstrated this to us more graphically than when we watched a rather groggy adult male fox squirrel emerge in the early morning hours and fall dead to the ground. Upon conducting a necropsy of this individual, we observed that he had 14 wounds from other squirrels and no visible body fat stores. He died primarily of malnutrition.”
And yet, this sad specimen was a winner: He had copulated five times that breeding season.
The Domestic Squirrel
Squirrel life isn’t always so competitive. They also cooperate. Eastern gray squirrels may live together in groups of two to nine, cuddling up in big leafy nests and grooming each other when they emerge in the morning. When it’s a group of females, they are usually related, and they keep coming back night after night—there’s an evolutionary benefit in taking care of someone when you share genes. The male groups aren’t as stable, but they are even more remarkable because they nest with compatriots that aren’t closely related. They are able to form alliances with other bachelors without the force of family.
The nests are properly called dreys. When Jo and I went looking for acorns we were looking down at first, searching the ground. But then, while under a big tree, I looked up. The leaves formed a thick layer of green around the farthest extent of the tree, but the interior stems of a coast live oak are bare. Looking up the trunk was like looking into the complicated mechanism of a massive green umbrella. I could clearly see a drey straddling two branches.
“Look, Josephine, do you want to see a squirrel house?”
She dropped the pinecone she’d been picking at and trotted over. “Where?”
I crouched next to her and pointed. “It looks like a big ball of leaves. See it?”
Jo laughed in her low, huffy chortle, which signifies deep satisfaction.
But even as I was pointing, I saw another, smaller drey, and then another, and another. Dreys are a perfect example of the unseen city: Even if you think you’ve never seen them before, you probably have—anywhere there are squirrels, there are dreys, hiding in plain sight. But they are easy to miss because they look so messy, like a mass of leaves lodged high in the tree. But masses of leaves don’t just lodge in trees. That takes intention.
Squirrels start by building a base of leafy forked branches, then pile twigs atop that until it’s at least a foot across. Then, according to squirrel researchers Monica Shorten and Frederick Barkalow Jr., they will “dive and wiggle into the middle of the heap, using hands and mouth to tug and bite, and, judging by what can be seen from a distance, the cavity is shaped by repeated body turns.”
After lining the interior with moss, leaves, shredded bark, and whatever else is handy, the squirrel has a waterproof home with an interior of about the size of a bocce ball, on average. Obviously the drey must be bigger for a larger group.
The entrance to a drey is always covered by leaves, but you can see squirrels coming or leaving if you are willing to spend some time waiting. Just before sunset is a good time to set up watch: That’s when they return to their homes. But unless you are up in the canopy, it’s hard to tell which squirrel is going into which drey. As we were looking up into the live oak’s branches, a squirrel materialized and clambered toward us.
“Does he live in that nest?” Jo asked.
I had no clue; he could have been lurking in the upper branches, so I answered with another question. “Maybe, but Josephine, how do you know it’s not a girl?”
“Because, Papa,” she said, laughing at my ignorance, “he’s not wearing earrings.”
Here’s how you determine the sex of a squirrel: Wait until it stands on its hind legs, and then look for nipples or testicles. Josephine was right about this particular squirrel—it was almost certainly a male, because it had no nipples. If you look closely, they are clearly visible, unless the female is less than a year old and hasn’t had babies yet. The males are trickier: They have pendulous scrotums, but they retract into their bodies during July and August, between mating seasons (in eastern gray squirrels).
Learning to recognize individuals is an important step in becoming a good field observer of squirrels, the researchers say, and learning to see which are males and females helps with that. Then you can begin to look for more subtle details, such as variations in color, patterns, or scars.
Individuals can also be identified by their behavior. The morning after we found the dreys, Josephine pointed out that our backyard squirrel had joined us for breakfast. It was perched on the fence a few feet from the dining room window, eating rose hips. I was sure it was the same squirrel, not because I could see any identifying marks, but because of the rose hips and his manner. Just as before, he was fervently unafraid. He continued shelling the pulp off the rose hips, then cracking the seeds inside, even when I opened the window and Josephine leaned out over the sill, not five feet away.
He returned the next day during breakfast, and the next. There was no doubt that it was the same squirrel. After finishing each rose hip he paused to wipe his short muzzle against the fence, first one side, then the other. He steadily depleted the supply of rose hips, clambering farther out into the hanging brambles to procure those he couldn’t reach from the fence. His movements were not particularly graceful. Twice I saw him fall, but he always caught himself immediately. Perhaps squirrels favor resilience over precision: Instead of calculating each movement like a rock climber, they just scramble forward and trust in their strong claws if a foothold fails.
After a week, there were no more easily accessible rose hips. There was one branch laden with red fruit, but it extended too precariously for our squirrel. He tested his weight on it and then retreated to eat the black rose hips of years past instead.
I picked one of the fresh rose hips to see what our squirrel was after. Inside were eleven slick seeds, each about the size and shape of a lemon seed. They were tremendously difficult to crack, and each time I succeeded in breaking through the husk with a knife, the pieces scattered across the kitchen. The black rose hips I picked contained only a couple of fat seeds, the rest being withered and thin. I picked a few of the fresh rose hips from the forbidden bough and left them along the top of the fence to see if our neighbor would take them, or if he now preferred the older vintage.
The next day my offering wa
s reduced to bits. I replaced it with several more rose hips, but these remained untouched atop my fence. Another puzzle. The squirrels gave me a clue the next morning. Often, I’ll hear squirrels—their claws on bark, or a tumult of clattering branches—before I see them. As I sat on the stoop lacing my running shoes, I became aware that there were at least two squirrels in the oak tree across the street. One bounded directly at me, and when it reached my front yard I could see that it held an acorn in its mouth. Perhaps the acorns had ripened and rose hips were suddenly passé.
The squirrel buried the nut and I kept my gaze fixed on the tuft of grass that marked the spot. Koprowski and Steele had written that “ultimately, the squirrels’ decision of what to eat and what to cache may determine the structure, composition, and population biology of our oak forests.” I would add that it’s not only our forests, but also our yards, medians, and city parks. I’d noticed two small sprouts emerging from the earth beside our house, both of them coast live oaks, and I realized it was entirely possible that this very squirrel had planted them. There was news breaking in my neighborhood that was going unreported: news of the squirrels’ plans for the long-term development of the urban forest, news of acorns ripening and the relative size of the year’s crop, news of the way the replacement of the eastern grays by fox squirrels had changed the rhythms of these cycles within cycles. I could see just enough to see what I was missing. I crossed the sidewalk and resolutely excavated the turf where I’d seen the squirrel bury the acorn. It was nowhere to be found.
BIRD LANGUAGE
One morning, after Josephine had talked her way into our bed—then spent the rest of the night rotating through a series of improbable sleeping positions—as we lay clinging to the last shreds of sleep, she asked why the birds were singing so loudly. I’ve grown so accustomed to the morning chorus of birds outside our window that I hadn’t noticed, but yes, they were rather loud.
“What are they saying?” she asked. “Why are they all tweet-twee-tweet?”
I considered this. Was there an answer to this question? Why do birds wake so early to talk to one another? And was it possible to divine the meaning of their songs?
There are scientists who think that birds sing at first light to signal that they have survived the night and are laying claim to their territory for another day. Others suggest that they sing in the time after waking when it’s still too dark to forage. I think both of these hypotheses can be combined with the one I find most compelling: They hash out their territorial rights when they first wake up, because it’s the time when there’s the least competition for the acoustic airspace. As I was researching this question I stumbled upon the story of the Talbots, a family living in southwest England, that demonstrated the point. I found and friended Ali Talbot on Facebook. A few days later I was chatting on the phone with her husband, Nathan. He laid out the story for me.
Every morning at 5:00 a.m., they would hear the siren. The Talbots live near a hospital, so sirens aren’t unusual, but this one was peculiar. Instead of sweeping by, it stayed put, as if the source was parked in their backyard. “The hospital is about half a mile from my house, so at first I thought it was an ambulance,” Nathan Talbot told me. “It woke me up every single day at 5:00 a.m. It was uncanny! It was like an alarm clock.” It cycled through the typical phases, sometimes stopping just long enough to make them think it was finished before starting again. And it happened every morning at the same time. Sometimes it would sound like the ringtone of a cell phone that never went to voicemail. Sometimes it sounded just like a car alarm. But there was something strange about it: Though the volume was just as jarring as sirens normally are, the timbre was slightly higher and thinner, more of a whistle than a siren. Eventually Nathan went out into his garden and sighted the culprit: a blackbird. It was perched right above his dormer window.
Wild birds all over the world have changed their tunes as the noises associated with people dominate cities. Most of these changes don’t involve mimicry—the blackbird in the Talbots’ yard was exceptional. Instead, birds are shifting their songs in order to compete with humanity’s hubbub, so they can be heard. In places where the morning commute creates tumult, birds have set their alarms earlier: Long before first light, they sing to declare the boundaries of their territories. If shifting their schedule is impractical, birds sometimes shift pitch instead, adjusting their vocal register up or down so they aren’t in competition with the buzz of engines.
One of the first people to realize that animals were listening to the songs of other species and adjusting their own songs to accommodate them was Bernie Krause, a musician turned natural-sound engineer. Krause was recording in Kenya’s Maasai Mara National Reserve when he had his epiphany. It was hours after midnight, and he was listening to the sounds of the reserves while drifting between wakefulness and sleep. “It was in that semifloating state—that transition between the blissful suspension of awareness and the depths of total unconsciousness—that I first encountered the transparent weave of creature voices not only as a choir but as a cohesive sonic event,” Krause wrote in his book The Great Animal Orchestra. “No longer a cacophony, it became a partitioned collection of vocal organisms—a highly orchestrated acoustic arrangement of insects, spotted hyenas, eagle-owls, African wood-owls, elephants, tree hyrax, distant lions, and several knots of tree frogs and toads. Every distinct voice seemed to fit within its own acoustic bandwidth.”
Put simply, each creature was filling a special place in the sonic spectrum, some of them the higher registers, others the lower. If this were a visual phenomenon rather than auditory, every species’ song would have been a different color of the rainbow, each one stacked above the next. When Krause printed out a visual spectrogram of his recording, it looked to him like musical notation: Each animal fit into its own track, where it wouldn’t overlap with and be muddied by the sounds of another. In a very real way, the animals were an orchestra: Each instrument made itself heard by producing a different set of frequencies. The elephants were the bass cellos, the hyenas the oboes, the hyraxes the clarinets, the insects the violins, and the bats the piccolos over the top.
In cities, however, a constant wash of mechanical noise fills a massive swath of the audio spectrum. Birds have adjusted, but there’s only so much they can change in what is in evolutionary terms—a short period of time. House sparrows are declining in some areas because, scientists suspect, they can’t communicate with one another. Some species of bat, which rely on echolocation to hunt, have moved out of noisy areas. And, of course, the problem isn’t limited to cities: Ship engine noise and the other sounds people make in the oceans can have deleterious effects on dolphins and whales.
All the noise is bad for animals, and for us. Constant exposure to mechanical noise is unpleasant, and there’s some evidence that it can chronically elevate stress and erode our health. One of its gravest effects may be the separation of humans from the orchestra of life. We’d be much more likely to quiet down if we were interested in listening to what our nonhuman neighbors were telling us—that is, if we all learned to speak the language of birds.
SONGS WITHOUT LYRICS
It turns out that learning to understand the bird language doesn’t require a magical amulet or an enchanted silver seashell, but instead something that’s arguably more difficult to come by: patience. When I picked up Jon Young’s book What the Robin Knows, I was a little worried I was about to waste my time trying to acquire occult knowledge. But as I read, I became impressed by the modesty of Young’s claims. He states the facts without embellishment, and offers a skill for the price of forced concentration.
I’d thought I’d start learning to identify birds by their songs, but Young admits that is sometimes impossible. He writes, “Even aces can have trouble identifying a new species on the basis of song alone.” Songs vary across the country, and across the yard. A Bewick’s wren may sing different songs than its father does a few hundred yards away. Instead of obsessing over species identificati
on, Young focuses on the salient landmarks in bird dialect, and on the way they correlate with behavior. He doesn’t try to recognize and read each trill and semiquaver for literal meaning. Instead, Young listens for the emotion and the intent behind the song. You’ve already done this, he points out, if you’ve ever listened to someone singing in a language you don’t understand: “Listening to Spanish, Italian, or German opera, you, like me, may have no idea what the words of a particular aria mean, but you don’t need this knowledge to understand the feeling they convey. You can tell if it’s a song of pleasure, jubilation, triumph, or tragedy.”
I found that if I focused on the birdsong, I could easily hear singing and scolding and—perhaps the most revealing sound-scape of all—silence. While reading Young’s book I couldn’t help but begin to notice the bird noises outside my window: peeps and chirps. It was a warm winter day, so I went out to the backyard to sit in the sun. As I was reading, monitoring the birdsong around me with a sliver of my attention, the chirping ceased. It was a subtle change, one I wouldn’t have noticed normally. The other sounds still continued, of course—the cars passing, the shouts of children at the nearby playground—but the underlying fabric of birdsong had disappeared, like a tablecloth whisked away from under the place settings with such delicacy that I would have missed it if I hadn’t been listening for it. I climbed the steps to my back door and stood on my toes to look over the fence. There were about a dozen students walking east on the greenway that borders my house. They were holding hands, forming a cordon that swept across the park. I felt a little shiver of triumph. The birds had told me that something was happening, and I had been ready to hear.
How to Hear Birds
Young’s method for learning bird language is simple: Find a spot and go there every day to watch and listen to birds. Though I had experienced my first triumph on that winter morning, I had actually been doing it wrong. First, I was reading, rather than giving my full attention to the birds, and second, my backyard is barely big enough for one little raised vegetable bed, and a high wooden fence surrounds it. I could hear the birds, but I couldn’t see them, so I couldn’t connect sounds to behavior.
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