By Benjamin Alva Polley EBS COLUMNIST
One summer evening, I was stationed at an isolated fire lookout in the Bob Marshall Wilderness when I overheard hoary marmots squealing alarms outside the glass-walled building. Also known as “whistle pigs,” a hoary marmot’s call is a long-drawn-out whistle followed by a long pause, then repeated at intervals. I kept searching as to why they were making a commotion. I scanned the trail for visitors, but they rarely came this late because I was 14 miles back. I checked the skies, searching for golden eagles, and swaggered outside to look over the cliff’s edges for other predators. The warnings continued for a solid 20 minutes.
Then, the calls abruptly changed. Instead of sustained seconds of a keened whistle followed by a long pause, they were a series of short, rapid half bleats with brief breaks. These shrieks continued for another 10 minutes. I realized a marmot colony was strung along the mountain kingdom’s broken cliffs. Their warnings were an invisible wire alerting others of danger beyond my periphery.
Animal language may be more complicated than we previously acknowledged, with some animals using sentences that contain nouns, verbs and adjectives, which researchers have discovered can be understood across various species. According to Dr. Erick Greene, a University of Montana biology professor, birds can understand “squirrelese,” and squirrels can understand “birdese.” Animals can also convey a lot of information in their alarm calls, including a predator’s level of threat and its specific behavior. For example, a squirrel can indicate whether a red-tailed hawk is flying around hunting or just passing.
Scientists have found that this information can travel incredibly quickly and across long distances. However, many alarm calls are subtle; most people don’t notice them as they sweep through the forest. Greene is studying bird language with the help of a mock predator. He had a taxidermist create several mechanical birds of prey, which he calls “robo-raptors,” using the taxidermy remains of northern pygmy owls. Greene’s research team arranges these birds in an undisclosed Rocky Mountain coniferous forest and observes the reactions as they remotely control a stump to reveal the decoy. When the “robo-owl” swivels its head, the birds suddenly hush, followed by a frenzy of sound as chickadees and red-breasted nuthatches flock and mob the owl, warning all eavesdropping species, from red squirrels to mule deer, that there’s a predator intruding.
Researchers like Greene have found that mammals, birds, and even fish recognize alarm calls from other prey species. Many small birds catch the newswire of one species and take notice. Chickadees and other members of the Paridae family act as forest crossing guards. Other prey species can listen at the same frequency and take notes by ducking or hiding. Squirrels, gophers and other birds mimic these alarm calls to help amplify the warning system. This sophisticated system, which can travel faster than 100 miles an hour, precedes the predator by a few minutes, showcasing the speed and efficiency of their communication.
Greene aspires to comprehend the language of the forest by decoding the nuances of bird alarms and their communication patterns. He gives an example of the chickadee bird, a well-known bird named after its call. Chickadees repeatedly make this call to urge other birds to mob and harass predators until they leave. Adding more “dees” to their call signals the predator’s size to other birds. One additional syllable means a larger predator threatens them—but may not threaten larger species.
For instance, a northern pygmy owl, about 2.2 ounces and 6.75 inches long, can easily match the chickadee’s maneuverability through the forest and pose a considerable risk. Therefore, chickadees add five to 12 “dees” when they spot a pygmy owl. Squirrels larger than the owl continue eating pinecones and making squirrel midden when they hear this specific call because they are not at risk. But small songbirds hide immediately, especially red-breasted nuthatches that winter flock with chickadees. It’s also likely that squirrels will take notice if they hear the chickadees’ description of a northern goshawk.
To investigate this sophisticated interspecies communication, Greene and his team joined forces with researchers from the Cornell Lab of Ornithology. They measured bird alarm calls using an acoustic microscope, and the signals appeared as a spectrogram on the screen, highlighting the collaborative spirit in understanding bird language.
Dr. Con Slobodchikoff, a Northern Arizona University biologist, debuted a similar instrument to decode prairie dog language. Slobodchikoff has pioneered research on prairie dog colonies in New Mexico, translating their complex language. His work, along with that of other researchers like Dr. Erick Greene, is revolutionizing our understanding of animal communication and behavior.
Biologists meticulously observed predators’ and prairie dogs’ behavior, noted their responses to alarms, and used advanced computer analysis to decipher the alarm call’s acoustic structure. The computer software generated a sonogram, a graphic representation of a vocalization’s frequencies and time values. Each alarm call, lasting one-tenth of a second, was repeated frequently, ensuring the findings’ accuracy.
Through rigorous statistical methods, researchers decoded the variability in a single chirp. A different key distinguished a coyote from a domestic dog or a person. To test this variability, the researchers had the same individual walk into a prairie dog colony wearing different colored t-shirts at various daily intervals. The subsequent alarm calls contained the person’s size, shape and clothing color. In some experiments, prairie dogs could even describe objects they had never witnessed.
The alarm calls are composed of smaller sound units akin to human phonemes—vowels and consonants. Each alarm call is like a human sentence, with nouns representing the species, verbs representing the activity, and adjectives describing the physical characteristics. For instance, a prairie dog chirp decoded from the experiment sounds like this: “A tall and thin, yellow-haired person wearing a green shirt and blue pants is running.” This groundbreaking research provides new and thrilling possibilities in experts’ understanding of animal communication.
However, prairie dogs also have social chatter that scientists haven’t yet decoded because they cannot tie some conversations to specific behavior changes during these vocalizations. “This research shows that prairie dogs have the most sophisticated animal language that has been analyzed so far,” Slobodchikoff said. “However, as other scientists start looking at animal signals concerning the messages’ context, we will see other animals have just as sophisticated languages. We will find that other animals have even more sophisticated languages.”
Mock road experiment
As we delve deeper into the intricacies of animal communication, we are confronted with a global issue. The artificial noise from quarries, natural gas development, factories, trains, airports and automobiles disrupt these critical communication lines. In the United States alone, studies reveal a staggering statistic: Over 80% of the land area now lies within two-thirds of a mile from a road.
Dr. Jesse Barber of Boise State University created a “phantom road” in a forest outside Boise, Idaho, examining how human noise interferes with animal and bird communication. That forest is an important rest stop for migrating birds. No road exists, but Barber and his team amplify the sounds of a busy highway on speakers that they can turn on and off. They found more than a one-quarter decline in bird abundance when the artificial road noise was switched on; some birds avoided the area almost entirely. In a 2013 study, Barber deduced that these birds changed their behavior and decided to route through a quieter area due to road noise.
“What we found was that the birds that did continue migrating here had lower overall body condition, and they gained significantly less weight when the road was ‘on,'” Barber said.
The impact of artificial noise is more than inconvenient for migratory birds—and other animal species—which are declining worldwide. It’s a threat to their very survival. One factor in this decline might be how artificial noises hinder their ability to gather information, such as warnings about danger and food sources, forcing them to alter their overall behavior. If birds can’t hear others’ warnings of danger, they must spend more time looking out and less time foraging. In winter, birds must gather enough calories to survive long, cold nights. Unnatural noise could create a trade-off between collecting food and being vigilant.
Species like prairie dogs and chickadees are more than just local communicators. They are purveyors of information, passing out vital facts to their immediate family groups and whatever other species may be eavesdropping. This is not a localized phenomenon but a global one, happening with all life forms.
Freely available information helps others. The information generated by chickadee or ground squirrel species worldwide is always trending in the communities where they live among hundreds of sparrows, thrush, warblers, woodpeckers and other animals that know the lingo. This communication feed could mean a better meal for this woodpecker so it can live another day.
Before industrialization, people listened to this language, which was older than words. This newswire is all we had. In our self-created anthropocentric universe, we began to think we had a monopoly on language. But now we again realize how these nonhuman languages invisibly string the world together. These soundscape components are evolutionarily crucial for species survival, and these species have evolved together in these socially complex networks. If we, as a collective, quiet the human world a few decibels, we may hear many other things we’ve been missing from this intricate, vast interspecies communication web. The power to make a difference is in our hands.
Back at the fire lookout, I continued eavesdropping on the marmot calls. I am sure I wasn’t the only species listening. I looked over the reef’s wall again as a mountain lion stole silently on big furry paws, creeping below. I watched the profile of its long, black-tipped tail airbrushing the sky as the muscular feline crouched, then leaped toward a bumbling marmot. The marmot dived down its black hole, barely escaping. I snapped photos before the tawny mountain lion vanished into the shadows. Later, I realized the first marmot whistle meant danger, and the second described lion hunting.
I was nervous knowing my neighbor was this large and stealthy, and lived here like a ninja. I looked over my shoulder more frequently whenever I left the safety of the fire lookout’s confines and tried to decode the language of other species to hear if they were alerting me of danger.
Benjamin Alva Polley is a place-based storyteller. His stories have been published in Audubon, Esquire, Field & Stream, The Guardian US, Outside, Popular Science, Sierra, and other publications on his website. He holds a master’s in Environmental Science and Natural Resource Journalism from the University of Montana.
