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August 13 - August 13, 2024
In many cultures, owls are deemed half bird, half spirit, crossovers between the real and the ethereal, considered by turns symbols of knowledge and wisdom on the one hand, and bearers of bad luck and illness, even death, on the other.
They are cryptic and camouflaged, secretive and active at a time when access to field sites is challenging. But lately researchers have harnessed an array of powerful strategies and tools to study them and unpack their mysteries.
Some owls cache or hoard their prey in special larders. Some decorate their nests. Burrowing Owls[*] live in underground burrows, sometimes alongside prairie dogs, and when threatened, will hiss like a cornered rattlesnake.
Owls are known as “wolves of the sky” for more good reasons than ever. Fierce hunters, they take all kinds of prey, from mice and birds to opossums and small deer, and even other owls. But they also occasionally scavenge, everything from porcupines to crocodiles and Bowhead Whales.
Owls may be known for their nocturnal way of life, but only about a third of owl species hunt solely at night. Others hunt at dusk.
Owls first appeared on earth during the Paleocene epoch, some fifty-five million to sixty-five million years ago. Tens of millions of years later, they split into two families, Tytonidae (barn owls) and Strigidae (all other owls).
Like all birds, they initially arose from a group of small, mostly predatory, running dinosaurs that were coexisting with other, larger dinosaurs sixty-six million years ago.
new research shows that owls are most closely related not to falcons or nightjars but to a group of day-active birds that includes toucans, trogons, hoopoes, hornbills, woodpeckers, kingfishers, and bee-eaters. Owls probably diverged from this sister group during the Paleocene, after most of the dinosaurs died off and small mammals diversified.
Now most owls share an array of remarkable features that distinguish them from other birds and give them a unique ability to hunt at night, including retinas rich in cells that provide good vision in dim light, superior hearing, and soft, camouflaged feathers tailored for quiet flight.
Some 260 species of owls exist today, and that number is growing. They live in every kind of habitat on almost every continent—from
Take barn owls. The oldest lineage of owls, barn owls probably first arose in Australia or Africa, spread through the Old World, and now live on nearly every continent.
That owl seemed like a messenger from another time and place, like starlight. Being near her somehow made me feel smaller in my body and bigger in my soul.
Smaller prey it will swallow whole. As with all owls, the indigestible parts—fur, bones, feathers, claws—are sequestered in the stomach and compressed into a pellet. The pellet remains there for hours until the owl regurgitates it, pushing it back up the esophagus and into the mouth for ejection.
In some ways, owls hunt like other raptors, pursuing their prey with strong talons and sharp beak. They have powerful muscles in their legs and feet and big talons, the better to seize and kill prey.
But most have long, well-muscled legs, up to half the length of their bodies, with strong bones, especially in their feet. Just before contact with their quarry, they thrust their powerful feet forward to strike, killing their prey with the force of the impact and crushing talons.
barn owls can hunt their prey in complete darkness using only sound.
The flat, gray facial disk of a Great Gray Owl is like one huge external ear, a feathered satellite dish for collecting sound.
Not all owls have the big, pronounced facial disks of Great Grays, Boreal Owls, and barn owls. It’s smaller in owls that rely less on sound for hunting—Great Horned Owls, Little Owls, pygmy owls.
The facial disk in owls that hunt primarily by sound is outlined with a ruff, or ring of stiff interlocking feathers that capture sound waves and channel them toward the ears, like people cupping their hands around their ears.
An owl’s auditory system shares with other birds another superpower we mammals don’t possess: it doesn’t age.
forward-facing eyes also give owls a vital gift for hunting: binocular vision.
For a sparrow or titmouse pursued by an owl, eyes on the side offer a wide field of view, the better to see that predator coming. Owls have a narrower total field of view, but their binocular vision gives them an enhanced ability to determine their direction of travel and the time required to reach a target—all big advantages in zeroing in on prey, especially if it must be caught with split-second timing.
Their night vision is better than ours, though not as keen as a cat’s.
owls molt to renew their plumage, regularly shedding feathers that are old or worn from rubbing together in flight or damaged by collisions with branches or grass or passing through the narrow opening of a tree hollow or cavity.
volunteers counted every feather on a dead female Great Horned Owl—a labor involving forty-six hours of work—they came up with 12,230 individual feathers. Eagles and most other birds of prey have about half as many.
Owls may not be silent fliers, but they are nearly so. In part this is because owls have low wing loading—their wings are big in relation to their bodies—so their flight is buoyant and slow, as slow as five miles per hour for a big bird like a barn owl, which makes it quieter. (Owls need to fly slowly to stalk prey in open fields and to navigate through trees and other obstacles in forests.) But it’s the marvelous and unique feathers and structure of owls’ wings that really hush their flight.
The only way for an owl to detect the true location of a vole’s snuffling under snow is to hover directly above it. And that is exactly what a Great Gray does. Most owls fly directly toward prey. Great Grays hunting in snowy areas fly to a spot above the prey and then hover for up to ten seconds before plunging straight down.
“We have a field station out in the desert,” he explains. “Deserts are phenomenally quiet environments, especially in the fall and winter. And so I went out there in September and put out a mouse in a small cage, with a microphone next to it. Then I put some dry leaves inside the cage with it. When you want to catch an owl, this is what you do so that the mouse walking around in the cage makes a sound that the owl can hear.”
They’re quiet, wary, secretive, and often elusive. They’re masters of camouflage—streaked like grasses; mottled, speckled, and striped like tree bark; pale like snow—to befuddle the eye of both predators and prey. They wear the look of the land around them to meld into it, a strategy known as crypsis.
The day Max found a family of four owls using only his nose, Hartman knew this was an important way of locating these owls. And it was completely noninvasive. “We didn’t have to see the owls or elicit hooting from them and attract unwanted attention.”
endangered Tasmanian Masked Owls. These owls are very rare and deeply secretive. They roost where they are least likely to be disturbed, in cliff-side caves or tree hollows or in the remaining old-growth forest of Tasmania, so they’re extremely hard to detect.
Barred Owls are native to eastern North America, but over the past century they’ve moved across the Great Plains and into the forests of the far West. There, they have effectively colonized the entire range of the Northern Spotted Owl, says Wood, displacing their slightly smaller cousins. “These two species just can’t coexist. They’re too similar ecologically, and it’s the spotted owl that loses because Barred Owls are bigger, more aggressive, and more flexible in what they eat—just all around competitively superior.
Barred Owls are really physically aggressive,” explains Wood. “Spotted owls quickly learn that if they’re vocalizing, this pisses off the Barred Owls, who don’t hesitate to swoop in and physically attack them to claim their territory. So where Barred Owl densities are really high, as they are in the Pacific Northwest, Northern Spotted Owls have gotten really quiet”—as
open water in winter—likely habitat for the owls. “The fish owls nest along rivers where the water doesn’t freeze,” she explains.
The fish owls nest in the holes at the top of broken trees, and they tend to use the same tree again and again,
Johnson likes to say that there are two important days in life, the day you were born and the day you find out why. Now he runs the Global Owl Project, a consortium of more than 450 researchers and conservationists in sixty-six countries working on the science and protection of owls.
It’s the job of a male Burrowing Owl to deliver food to the burrow to feed the female. She likes fresh food, so the male doesn’t kill the insects, just disables them, says Johnson. (Rodents he won’t leave alive because they’ll escape.)
He delivers spiders and moths and other insects and leaves them within a foot or so of the burrow mouth. “When you walk up to the nest site at night, you’ll see the eye shine from a lot of insects and spiders,” says Johnson. At one nest, he found thirty-two wolf spiders. (“That guy specialized in wolf spiders.”) The insects and spiders are still alive, but they can’t get away. “How do the owls know to do that?” he wonders aloud. “The male goes off, catches something, cripples it, brings it back, drops it off, and then goes to get another one. That’s impressive.”
owl is female because she’s bigger than her male counterpart would be, and darker. During the nesting season, the feathers of males bleach out in the sun as they stand guard over the nest.
She was taken to a raptor rehabilitation center before she could fully see and was cared for by people there, which caused her to imprint on humans rather than other owls. Now she’s not fearful of people and is psychologically inclined toward relationships with them.
This, together with her significant injury, meant she was incapable of surviving on her own. “The
“Owls basically see their world through their ears. They’re mostly active at night or at dawn or dusk, so vocalizations are essential to their communication. They don’t just hoot for the hell of it. They vocalize for a reason, and they convey meaning in their calls.”
Bloem’s freezer is full of pocket gophers, rats, and mice, which she disembowels before serving to Alice. During mating season, Alice will hoot the night through, which makes for spotty sleep. “And then you’ve got those razor-sharp talons,” she says. “If she has some cached food in her room that I am not aware of and I get too close, she runs over and pounces on my feet. Normally she doesn’t grab hard, but it’s still enough to poke holes.
Naturalist Ernest Thompson Seton called these owls “winged tigers.” The scientific name for the Great Horned Owl is Bubo from the Latin for “horned or hooting owl,” and virginianus because it was first spotted by western naturalists in the Virginia colonies.
“Owl vocalizations are generally accepted as genetically inherited, not learned,” so Alice’s hoots and calls were likely a programmed part of her behavioral repertoire. Unlike songbirds, which learn their songs through vocal learning, just as we learn to speak—by listening, imitating, and practicing—owl calls and songs are hardwired, genetically fixed.
Researchers have taken owl eggs and put them in an incubator and then played the songs of song sparrows and other kinds of birds to them, David Johnson told me. As soon as the owlets are adult enough to call, they always sing “owl,” the calls of their species.
Like most owls, Great Horned Owls are highly territorial. They perch at the edge of their territory and establish its bounds with their voices, uttering deep, soft hoots in a stuttering rhythm: hoo-h’HOO-hoo-hoo. Both males and females give territorial hoots on their own, singing simultaneously with a mate, or even dueling with a neighbor or stranger owl.
Hungry young owls beg for food with a harsh, screeching squawk. Females away from their young make this call, too. It’s a sound that’s easy to locate and effective in communicating over short distances.
if a nesting Great Horned Owl is threatened by a dog or other predator, it will fluff up its feathers and throw itself to the ground, flapping around as if its wing is injured and squealing once or twice—a highly risky move and an indicator of what good nest protectors these birds can be.
she discovered that owlets begin vocalizing in the egg, even before they hatch.
