How Giant Face Owls Use Their Wings and Face to Find Moving Food With High Accuracy

According to a new study, several physical features of great gray owls, particularly parts of their wings and face, help them correct for sonic distortions caused by snow, allowing them to find hidden, moving food with astonishing accuracy.

giant-faced owls snag voles hidden in snow

(Photo : James Toose/Unsplash)

Hovering over a target assists giant-faced Great Gray Owls in locating prey hidden beneath two feet of snow.

According to a new UC Riverside study, several of the owls' physical features, particularly parts of their wings and face, help them correct for sonic distortions caused by snow, allowing them to find moving food with astonishing accuracy.

Unlike most owls, this species hovers just above a target area before diving straight down and punching through the snow with its talons.

"These aren't the only birds that hunt this way," said UC Riverside biologist Christopher Clark, who led the study. This species specializes in snow hunting.

Clark and his colleagues conducted a series of experiments this year in the forests of Manitoba, Canada, to better understand the owls' precision despite limited visibility and sounds due to snow. Their findings have been published in the Proceedings of the Royal Society B.

The owls' broad disc-like face, which they use like radar to find food, is a key discovery. The fleshy part of our ears functions similarly to their facial features. Sound is directed toward their ears, which are located near the center of their faces, through an opening under their feathers.

Low-frequency sounds are more sensitive to larger facial discs. Great gray owls are built for hunting voles, their preferred food, and have the largest facial disc of any bird.

Voles have high-pitched voices that get lost under snow cover and are frequently misidentified as mice. Their digging and chewing sounds, on the other hand, are picked up by the owls' facial radar.

The researchers dug holes next to the ones they saw the owls create while hunting to demonstrate how snow affects the voles' sound.

They installed speakers inside the holes that played a variety of sounds, including high-frequency white noise and low-frequency recordings of burrowing voles.

An acoustic camera comprised of multiple microphones recorded sounds emerging from the snowpack at six different depths.

Low-frequency noises transmitted the best, according to analysis. Only sounds with frequencies of 3 kilohertz or lower were transmitted through layers of snow 20 inches thick; all high-frequency sounds vanished.

The group's acoustic experiments also revealed that snow bends the voles' sounds, creating an "acoustic mirage" that could lead owls astray.

The birds compensate for the distortions caused by the snow by spending a brief moment directly above their prey.

Great gray owls also have wings that appear to dampen the sound of flying, which may allow them to focus on the noises made by the voles.

Because of its long, fringed wings coated in thick "velvet," this species is one of the quietest in flight among all owls, which may be especially useful during the hovering phase of the hunt.

Read more: New Species of Owl Discovered in Philippines

Characteristics and Behavior of Owls

Owls spend the night hunting in desolate areas such as cemeteries, run-down farms, and other open areas.

Many owls feed primarily on rodents and other small animals. Prey is typically consumed whole, but the entire prey is not digested.

The undigested portions of the prey, such as fur and bone, are compressed by an owl's digestive tract into a compact pellet that the owl coughs up and expels through its mouth.

Instead of building their own nests, owls simply take over other birds' abandoned nests.

Barn owls are commonly found in structures such as barns, belfries, and abandoned buildings.

During cold weather, they also nest in cliff crevices, hollow trees, and dense evergreen trees.

Human encroachment on owl territories has resulted in a decline in wild owl populations.

Many owl species are unable to adapt to human-caused changes in their ecosystems.

As a result, the future of many owls, including the well-known barn owl, is uncertain.

Owls are members of the phylogenetic family Aves. The more than 200 owl species are divided into two families.

Barn owls are classified into 17 families, with the remaining species belonging to the Strigidae family.

The earliest known owl fossils date from the Miocene period, which lasted 38 to 54 million years.

Based on fossil evidence, these ancient owls evolved into the two modern owl families.

The oldest barn owl fossils discovered so far are thought to be at least 24 million years old.

Fossil evidence suggests that between 10,000 and 30,000 years ago, giant barn owls thrived in the Caribbean and Mediterranean regions.

These Ornimegalonyx were 2 to 3 times the size of modern barn owls and twice the size of modern great horned owls.

Ornimegalonyx is thought to have preyed on animals as large as a giant sloth and giant rodents as large as a capybara.

The world's owl species number 134, with the Eurasian eagle owl being the largest and the elf owl being the smallest.

Although owls share many characteristics, there are some significant behavioral differences between species. The majority of owl species are nocturnal, with the remaining third being diurnal.

Related article: The World's Biggest Owls Are Now Endangered: Is it too late to save them?