What an Owl Knows: The New Science of the World's Most Enigmatic Birds

by Jennifer Ackerman

pick up the sounds of the owlets in the egg about two days before they hatched. They break into the air cell in their egg and start breathing air. That’s when they start vocalizing. You can actually hear the little chitters of the chicks in the egg.”

they interact mainly through vocal communication over multiple seasons and over years.” It makes sense that their voices would be distinct and stable, to recognize one another and maintain long-term pair-bonds, to reunite in consecutive breeding seasons, to know who their neighbors are.

seizing birds and bats in full flight.

It’s also notorious for feeding on its predatory cousins—hawks, buzzards, and other diurnal raptors—sometimes systematically searching rock crevices and snatching a Northern Goshawk or Eurasian Hobby from its nighttime roost. “We’ve found Peregrine Falcon bands in their nests,” says Savelsberg, “along with the remains of coots, geese, Long-eared Owls. You name it, they eat it.” They will even eat a hedgehog after peeling its spiny skin.

pure muscle, muscle covered in velvet, so soft and strong at the same time.

Courtship in owls is like this. No strutting around or flashing of splashy, colorful feathers, mostly just mutual hooting. “If you’re an owl, you’ve got to sing to attract a mate,” says Holt. “Big owls hoot. Little owls toot. That’s their whole thing, vocalizations.” But what hooting it can be, the choicest and most persuasive owl language.

“because owls don’t make their own nest structures, but he’s hoping to attract a female to come and check him out and check out the real estate.”

Owls may be skilled hunters and mate finders, but skilled nest builders they are not.

Short-eared Owls tend to simply nestle in the grass, scratching out a bowl-shaped pit and filling it with grass and downy feathers.

Snowy Owls excavate their shallow nest bowls on mounds on the Arctic tundra.

Most owls don’t construct their own nests at all, but rather they appropriate structures built by other animals. The male usually finds a territory with abundant prey and some good nesting possibilities, but the female selects the actual nest sites.

Some species, like Long-eared Owls and Great Horned Owls, settle into old, abandoned stick nests vacated by magpies, crows, or hawks.

Barn owls typically nest in the rafters of barns, in empty...

or in cavities alon...

Burrowing Owls live up to their name by nesting in underground tunnels dug by ground squirrels, prairie dogs, bad...

The smaller species—Northern Pygmy, Northern Saw-whets, Flammulated, screech owls—find natural tree cavities or ready-made holes created by woodpeckers, sometimes in snags, standing dead trees that...

Taking up residence in a prebuilt nest is not a bad strategy. It means a breeding bird doesn’t have to expend en...

Night work in bear country: searching for owls is not for the faint of heart. “It’s not uncommon for bears to be found around Great Gray nests,”

“They prefer the same types of habitat and sometimes even eat the eggs and chicks.” But, she says, she has developed some comfort with it.

this bedecking is not about mate attraction or courting. The male starts ornamenting only after the female has begun laying eggs. It’s partly to provide soft nesting material for her to shred and line the nest cup, but it goes well beyond that. You can’t really shred a corncob or a seed potato. One

It’s a big flag to their species—and to ours—that the burrow is occupied. One male decorated his burrow with 122 pieces of coyote scat.

“We work with forest managers and timber harvest projects, even responsible foresters who think they’re never going to cut down a tree with an owl nest. But it took us two years to find that nest even knowing one was there somewhere—it was just so hard to see it from the ground. It’s really scary to think that that tree could so easily have been cut.” This is why it’s so urgent to locate and map owl nests, whether in cavities in an aspen grove or on broken-top snags or in old hawk nests high up in a Ponderosa Pine. If the nests aren’t found and flagged, their host trees may come down.

describes a nesting hollow in a tree that had been used for more than ten years by a pair of Powerful Owls. Fires ripped through the area and burned the tree from the inside out. After the fire, the pair sat in an adjacent tree. “Large forest owls make a really obvious grieving noise when they’ve lost a chick,” she says. “And they did the same thing for this tree hollow. It was quite heart-wrenching.” Once

It’s quite another to see a big female like this so nearby, tucked into her nest like a queen settled on a rough-hewn barrel-shaped wooden raft.

The whiteness of the eggs we see in that little cavity is usual for owl eggs but unusual in the bird world at large. Most bird eggs are elaborately colored for camouflage.

The eggs are concealed, so there’s little reason to expend precious energy producing pigments for them. Owl eggs are also different in shape from most bird eggs, rounder, probably for reasons having to do with flight,

The eggs of birds that are airborne most of their lives—murres, sandpipers, albatrosses—are elliptical, the theory goes, streamlined to fit through the pelvis of the birds’ smaller, lighter, and more compact skeletons. Owls, which tend to fly only in short glides, have a heavier skeleton and a wider pelvis that can accommodate more spherical eggs.

after the chicks hatch, demand for food increases exponentially, and by day ten or eleven, the chicks’ needs are so great that the female joins the male in hunting.

I’ve seen a male Great Horned Owl spread his wings over the female and chicks to shield them from the pouring rain, drenching his own feathers in the process.

Eastern Screech Owls in Texas bring live blind snakes to their nestlings, not just for food but perhaps to keep their nests tidy and sanitary as well. The chicks will eat some of the snakes, but most of the tiny (and seriously bizarre) serpents will live alongside the owlets in the nest debris and eat the parasitic fly and other insect larvae in decomposing pellets, fecal matter, and uneaten prey.

Scientists have found that nestlings with live-in blind snakes grow 50 percent faster and experience lower mortality than broods lacking serpentine company.

Successfully raising young is such an energy-demanding task that the adults routinely lose as much as a third of their body weight during the nesting season. In pouring their resources into their offspring, they also forgo molting their feathers—a process that consumes significant energy. Duncan

During the day most owls hide away in roosts to rest in safety after a long night hunting. Screech owls creep into dark tree cavities.

Great Horned Owls seek perches high up in densely needled conifers. Some owls take shelter in caves, like barn owls, Little Owls, and masked owls. The Spectacled Owl rests in the canopies of rainforests and gallery woods, where predators are few. Male Powerful Owls roost in high trees, sometimes atop their dead prey. Saw-whets will nestle in almost any kind of refuge, as long as it offers impenetrable protection—snarls of honeysuckle and dense groves of rhododendron or thickety pitch pine.

“Even though this is the biggest owl in Europe, the owl often slept with one eye open, and kept that eye facing away from the cliff wall, as if watching for threats,”

unihemispheric sleep has never been observed in owls, which might have something to do with the way their front-facing eyes are wired to their brains. In other birds, each half of the brain receives input from the opposite eye. In owls, each hemisphere receives visual input from both eyes. “So, when owls sleep with one eye open, both the left and right sides of the brain receive similar amounts of visual input,” he says. “In theory, this may cause both hemispheres to sleep less deeply than when both eyes are closed,” but this has never been proven.

in Kikinda, a small town in northern Serbia near the Romanian border. It seems an unlikely spot for the planet’s largest gathering of any owl species. But each year from November to March, hundreds of Long-eared Owls roost each day in the trees at the center of town.

Why the birds are here in Serbia in such great numbers has to do with agriculture, specifically with food supply for the owls and the agricultural methods that sustain it. The whole region of northern Serbia is agricultural, and farmers avoid rodenticides and use more old-fashioned methods of harvesting that leave plenty of grain on the ground.

the most common small forest raptor in North America. When I started working with saw-whets in the mid-1990s, they were the symbol of the state Wild Resource Conservation Program and a candidate species for the state endangered species list because everybody thought they were really, really rare. And it turns out they’re just really, really rarely seen because they’re so highly secretive and highly nocturnal.”

Testing owls for lead poisoning is a relatively new thing. Lead analysis used to be routine only in eagles and vultures, scavengers that were likely to feed on the gut piles that hunters leave behind, laced with lead fragments from bullets. But there’s a growing concern that owls are also ingesting lead from spent ammunition, perhaps by eating a squirrel that was shot but not killed and still carries bullet fragments.

Thirty percent of Barred Owls tested positive for lead, 30 percent of Eastern Screech Owls, and 19 percent of Great Horned Owls. “Unfortunately, lead is everywhere,” says Pierce, in opossums, squirrels, even box turtles.

Baby owls need this. When an owl chick hatches, it doesn’t instinctively know what it is. Imprinting on a member of its own species helps a baby bird learn and interpret species-specific behaviors and vocalizations so it can choose appropriate mates later in life. If an owlet imprints on a human, the owl will never be owl enough to survive in the wild.

It’s easy for an owl to make the mistake. Our faces look owllike to them, just as their faces look humanlike to us. As Laura Erickson put it, “They respond to us the way we respond to them.” If a baby owl imprints on humans, it won’t fear them. But it won’t necessarily be friendly toward people either or welcome their contact.

to read a bird by looking at its eyes, its feathers and tufts, its feet, and its body posture. All these body parts reflect an owl’s feelings, its emotions, its thoughts.

birds “that tell people things.” Birds move between earth and sky, day and night, so who better to turn to for clues? There’s even a name for it, avimancy, from the Latin for bird and the Greek for prophecy.

Later, my cousin wrote to me to say that the night her mother died, an owl “kept hooting nearby. Maybe it was just a coincidence,” she said, but in the forty-one years she had been visiting her mother, she had never heard an owl hoot anywhere near the house.

In many parts of the world, owls were—and still are—viewed as messengers bringing news from this world or others, from the past or the future.

It’s not hard to understand how a half-glimpsed barn owl, ghostly white, with its strange funereal night cries and habit of haunting vacant buildings, might give rise to the notion of a birdlike incarnation of a demon or spirit being.

The “old” part is still a question. Although owls in the wild can live up to twenty-five years, most have a much shorter life span. Big owl species live longer than smaller ones.

Also, he says, owls are playful, especially young owls. Scientists suspect that play depends on cognition, and that species with relatively bigger brains tend to play more. Play is not easy to recognize or define in the animal world, but evolutionary psychologists have come up with a set of criteria for identifying it. Play is activity that’s exaggerated, awkward and inappropriate, nonfunctional, and repetitive. It’s generally spontaneous, intentional, pleasurable, and rewarding, and initiated only when an animal is relaxed.