On a drizzly day in Grünau im Almtal, Austria, a gaggle of greylag geese shared a peaceful moment on a grassy field near a stream. One goose, named Edes, was preening quietly; others were resting with their beaks pointed tailward, nestled into their feathers. Then a camouflaged speaker that scientists had placed nearby started to play. First came a recorded honk from an unpartnered male goose named Joshua. Edes went on with his preening. Next came a honk that was lower in pitch than the first, with a slight bray. Edes looked up. As the other geese remained tucked in their warm positions, incurious, Edes scanned the field. He had just heard a recorded “distance call” from his life partner, a female goose whom scientists had named Bon Jovi.
Edes and his fellow-geese live near the Konrad Lorenz Research Center for Behavior and Cognition, which is named for a Nobel laureate whose imprinting experiments, in the nineteen-thirties, convinced goslings that he was their mother. (They took to following him in a downy line.) Greylag geese in the area have been studied continually ever since. The director of the center, a biologist and bird ecologist named Sonia Kleindorfer, showed me footage of Edes to demonstrate the subtlety of goose communication.
Geese maintain elaborate social structures, travel in family groups, and can navigate from Sweden to Spain. In a fight, an unpartnered greylag goose has a higher heart rate than a partnered one, and the heart rate of a recently widowed goose can remain depressed for about a year. These birds have things to discuss. Still, geese are not the Ciceros of the bird world. A lyrebird sings long, elaborate songs; ravens really can say “nevermore.” Geese are known for nasal honks. How much nuance can there be in a honk?
Greylag geese, it turns out, have at least ten different kinds of calls. “We are completely underappreciating the way they communicate,” Kleindorfer told me. “They give a departure call when they leave, and a contact call after they arrive. They know if their allies are there, if the bold geese are there. There is so much information that geese are getting from calls.”
Bird vocalizations are usually divided into songs and calls, but these are wobbly categories. What is designated a song in one species may be shorter in duration than what, in another species, is termed a call. Onomatopoeic groupings such as tseets, chirrups, rreeyoos, seeew-soooos, and dahs are also indeterminate: people transcribe the same sounds in different ways, and no bird version of the Académie Française exists to adjudicate. The vocalizations of birds are fundamentally incommensurate with human ones. We have a larynx and two vocal cords; they have what’s called a syrinx, which is a bit like having two larynxes that you can use at the same time.
Kleindorfer, the daughter of a mathematician and an actress, looks like a cross between a hiker and the film star Sophia Loren. From February to April, she researches Darwin’s finches in the Galápagos; from September to December, songbirds in Australia; and, for the rest of the year, the geese outside her office door. Early in her education, as an undergraduate at the University of Pennsylvania, she was taught that “male songbirds sing, females don’t, and if females do sing it’s an error.” The attitude at the time, she told me, was that “females are drab, inconspicuous, and quiet.” A few years after earning a Ph.D. in zoology at the University of Vienna, Kleindorfer took a job as a research biologist at Flinders University, in Australia, where songbird species originally evolved. “Imagine my surprise,” she told me. “I heard all these females singing songs as complex as the male songs.” Much of her ensuing career has focussed on bird vocalizations that were either underappreciated or unknown.
Kleindorfer decided to study bird eggs and early development, which were then neglected research topics. “Maybe this was because only females have eggs and I was a woman in science,” she told me. “I don’t have a better reason.” Kleindorfer had noticed that mustached-warbler chicks seemed to respond to the alarm calls of adult warblers, even though the thinking at the time was that such calls were directed at other adults, or possibly at predators. “If I put a snake nearby, the parental alarm call made the chicks in the nest jump,” she said. “If I put a marsh harrier”—a hawklike predatory bird—“nearby, the response to the parental alarm call was that the chicks would duck.” The chicks were responding appropriately to different alarm calls—a satisfying finding.
Kleindorfer also studied the superb fairy wren, a songbird that weighs about as much as a walnut and sports a flirty, upright tail. Despite their fanciful names, fairy wrens are commonplace in Australia. They are socially monogamous but sexually promiscuous—they are essentially in open marriages—and they bring up their young collectively. Arguably, they have even more to chat about than geese do. Fairy-wren nests are about the size of cupped human hands, built to contain pale, speckled eggs that are smaller than thumbnails. Kleindorfer and her team wired up nests with cameras and microphones and soon discovered something that they hadn’t known to look for. “The mothers in nests were producing an incubation call—a call to the eggs,” she told me. It was like a lullaby. Why would a mother bird make any sound that could attract predators to the nest? “Songbird embryos don’t have well-developed ears, so this was completely unexpected,” she said. “That started a twenty-year project—why is she calling to the eggs?”
The team compared incubation calls to the begging calls of young chicks. “It was very odd,” Kleindorfer recalled. “Each nest had its own distinct begging call.” What’s more, each begging call matched an element from the mother’s incubation call. This suggested, startlingly, that birds could learn a literal mother tongue while still in ovo. (Humans do this, too; French and German babies have distinct cries.) Even “foster” chicks, who as eggs were physically moved from one nest to another, learned begging calls from their foster mothers, rather than from their genetic mothers. This was big news in the ornithology world. “The paradigm of how songbirds learn—after hatching, from their father’s song—was overthrown,” she said. The same process was soon documented in more songbird species.
Language is often cited as the quality that distinguishes us as humans. When I asked Robert Berwick, an M.I.T. computational linguist, about birds, he argued that “they’re not trying to say anything in the sense of James Joyce trying to say something.” Still, he and Kleindorfer both pointed out that humans and songbirds share a trait that many animals lack: we are “vocal learners,” meaning that we can learn to make new sounds throughout our lives. (Bats, whales, dolphins, and elephants can, too.) “To me, the most amazing thing is that every generation of vocal learners has its own sound,” Kleindorfer said. “So, just like our English is different from Shakespeare’s English, the songbirds, too, have very different songs from five hundred years ago. I am sure of it.” We humans have long tried, often mistakenly, to differentiate ourselves from nonhuman animals—by arguing that only we have souls, or use tools, or are capable of self-awareness. Perhaps we should see what the birds have to say.
Animals have prominent speaking roles in many of our oldest stories. Eve has a memorable conversation with a snake. In Norse mythology, two ravens, Huginn and Muninn, serve as spies to the god Odin, whispering to him the news of the world. In many cultures, the “language of birds” refers to a divine or perfect language—the language of angels. In the scientific realm, however, the notion that nonhuman animals use language is often seen as foolish or naïve. Some birds may be excellent mimics, like parrots, but they can also mimic chainsaws or barking dogs; scholars don’t usually consider imitation a form of understanding. The prevailing dogma is that birds sing either to impress mates or to defend their territory. (I suspect that most of human communication could also be slotted into those categories.) In college, I was taught a stranger but similarly diminishing idea: that songbirds sing in the morning to burn fat, so that they are light enough to fly around during the day. Apparently, this idea is no longer taken seriously.
Even among species we view as being closer to ourselves, such as primates, scientists have tended to talk about “communication” instead of “language.” But it’s tricky to say where the line is, or what we mean by “communication,” since even bacteria communicate, as Berwick pointed out to me. “I think it’s best to think of language not as speech but as a cognitive ability in the mind that sometimes leads to speech,” he said, giving the example of inward conversations we have with ourselves. The linguist Noam Chomsky has said, “It’s about as likely that an ape will prove to have a language ability as there is an island somewhere with a species of flightless birds waiting for humans to teach them to fly.” Chomsky’s 2017 book on the evolution of language, co-authored with Berwick, is titled“Why Only Us.”
Over the years, however, some researchers have looked closely at the contexts in which certain animal vocalizations are made. In the late nineteen-seventies, two primatologists, Dorothy Cheney and Robert Seyfarth, were studying vervet monkeys in Kenya. Vervets have dark faces and pale fur; they are about the size of a small backpack and are hunted by pythons, eagles, and leopards. Cheney and Seyfarth documented something remarkable: one recorded vervet vocalization made vervets look up, presumably for eagles; another made them look down, presumably for pythons; and a third sent them running up into the trees, a good defense against approaching leopards. Young vervets sometimes use these calls faultily, perhaps sounding a leopard alarm for a warthog. But they get better as they grow up. They learn.
A newer generation of scientists has been trying to understand bird vocalizations. The alarm calls of Siberian jays can be said to have been partially translated. One of their screeches indicates a sitting hawk (which prompts other jays to come together in a group), another a flying hawk (jays hide, which makes them difficult to spot), and a third a hawk actively attacking (jays fly to the treetops to search for the attacker, and possibly flee). When cheery birds known as tufted titmice make a piercing sound, other titmice may respond by collectively harrying an invading predator. Some birds even lie. Fork-tailed drongos—common, innocuous-looking little dark birds that live in Africa—sometimes mimic the alarm calls of starlings or meerkats. Duped listeners flee the nonexistent threat, leaving behind a buffet for the drongo.
Upon seeing an owl, a chickadee might sound a loud chick-a-dee-dee-dee, adding dees in relation to how dangerous the predator is perceived to be. This call is also understood by nuthatches, which will join in to mob and harass the predator, forming a kind of defensive alliance. If you record an Australian bird warning of a nearby cuckoo—cuckoos leave their eggs in the nests of other species and often kill their step-siblings—birds in China will understand the call.
