Researchers begin to unlock owl’s secrets of the night
Owls are a staple of children’s books and cultural kitsch. Yet for all this apparent familiarity, only lately have scientists begun to understand the birds in any detail, and to puzzle out the subtleties of behavior, biology and sensory prowess that set them apart.
The New York Times
WASHINGTON — The day after a frigid, star-salted night spent tramping through the Alexandria, Va., woods with David Johnson of the Global Owl Project, and listening to the stridently mournful cries of wild barred owls that remained hidden from view, I stopped by the National Zoo around sunset to take visual measure of the birds I had heard.
The two barred, or Strix varia, owls were just rousing themselves in the outdoor enclosure, and they looked bigger and more shaggily majestic than I expected, with capes of densely layered cream-and-coffee plumage draped on their 17-inch frames and pompous, Elizabethan feather ruffs encircling their necks. Like any good royalty, they ignored me.
That is, until I pulled out my phone with the birdcall app and started playing the barred owl song. The female’s languid eyes shot wide open. The male’s head spun around by 180 of the 270 degrees an owl’s head can swivel.
With the distinctive forward-facing gaze that can make owls seem as much human as bird, the pair stared at me. I played the call again, the male grew bored, and I was about to put the phone away when suddenly the female — the larger of the two, as female birds of prey often are — pitched her body forward on her perch, lifted up her heavy, magnificent wings and belted out a full-throated retort to my recorded call.
After a brief pause, she hooted the eight-note sequence once more, at which point an astonished zoogoer nearby burst into applause.
“Everyone loves owls,” said David J. Bohaska, a paleobiologist at the Smithsonian’s National Museum of Natural History, who discovered one of the earliest owl fossils. “Even mammalogists love owls.”
Owls are a staple of children’s books and cultural kitsch — here wooing pussycats in pea-green boats and there delivering mail to the Harry Potter crew. Yet for all this apparent familiarity, only lately have scientists begun to understand the birds in any detail, and to puzzle out the subtleties of behavior, biology and sensory prowess that set them apart from all other avian tribes.
Researchers have discovered, for example, that young barn owls can be impressively generous toward one another, regularly donating portions of their food to smaller, hungrier siblings.
The scientists also discovered that barn owls express their needs and desires to each other through a complex, rule-based series of calls, trills, barks and hoots, a language the researchers are now seeking to decipher.
“They talk all night long and make a huge noise,” said Alexandre Roulin of the University of Lausanne, who recently reported on barn-owl altruism in the journal Animal Behaviour with his colleague Charlene A. Ruppli, and Arnaud Da Silva of the University of Burgundy. “We would never put our nest boxes in front of a farmer’s bedroom, or the person wouldn’t be able to sleep.”
Other researchers are tracking the lives of some of the rarer and more outlandishly proportioned owls, such as the endangered Blakiston’s fish owl of Eurasia. Nearly a yard high, weighing up to 10 pounds and with a wingspan of 6 feet, the Blakiston’s is the world’s largest owl, a bird so hulking it’s often mistaken for other things, according to Jonathan Slaght of the Wildlife Conservation Society’s Russia program. It could easily look like a bear in a tree or a man on a bridge.
This powerful predator can pull from the river an adult salmon two, three or more times its own weight, sometimes grabbing onto a tree root with one talon to help make the haul.
Ferocity is essential for a bird whose frigid, spotty range extends across northeastern China, the Russian Far East and up toward the Arctic Circle, one that breeds and nests in the dead of winter, perched atop a giant cottonwood or elm tree, out in the open, in temperatures of 30 degrees below zero.
Slaght’s colleague Sergei Surmach videotaped a female sitting on her nest during a blizzard. “All you could see at the end was her tail jutting out,” Slaght said.
Aeronautical engineers are studying owls for clues to better wing designs. Many species are renowned for their ability to fly almost silently, without the flapping noises and air whooshes that might warn prey of their approach.
The birds own the night, although some hunt at dusk and dawn and even during the day. And hunt owls tirelessly do. By one estimate, a group, or “parliament,” of 10 owl families living in a barn in Central Florida cleared the surrounding sugar-cane fields of about 25,000 cotton rats a year.
Owls were long thought to be closely related to birds of prey such as hawks and eagles, which they sometimes superficially resemble — hence the names hawk owls and eagle owls. But similarities of beak or talon turn out to be the result of evolutionary convergence on optimal meat-eating equipment, and recent genetic analysis links the owls to other nocturnal birds, like nightjars.
Through the Global Owl Project, Johnson is working with researchers in 65 countries to compile a vast database and celebration of all the world’s owls, with descriptions, natural history, genetics, vocalizations, rough population estimates, owl myths and legends.
Westerners love owls, he said, a tradition that dates back at least to the ancient Greeks and the association of owls with the wise goddess, Athena, and her gray “shining eyes.” In some countries, though, owls are seen as bad omens and harbingers of death — perhaps, Johnson proposed, because owls often nest in cemeteries, where trees are left to grow undisturbed and the nesting cavities are comfortably large.
Would that owls might lend us their ears. Species like the barn, barred, screech and horned have some of the keenest auditory systems known, able to hear potential prey stirring deep under leaves, snow or grass, identify the rodent species and even assess its relative plumpness or state of pregnancy, based on sound alone.