HomePLANTS & ANIMALSHow giant-faced owls snag voles hidden in snow

How giant-faced owls snag voles hidden in snow

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A new study led by the University of California, Riverside, discovered that giant-faced great grey owls can pinpoint prey hidden under up to two feet of snow by hovering for a few moments over it. Some of these owls’ physical characteristics, such as the shape of their wings and face, aid in correcting for sonic distortions caused by snow. It allows them to find their often rapidly moving prey with incredible accuracy.

Most owls fly straight at their prey. But great grey owls hover above the target area for a few seconds before dropping down and punching through the snow with their talons.

“These aren’t the only birds that hunt in this manner. But they are the most extreme because they can find prey so far beneath the snow cover,” said study lead author Christopher Clark, a biologist at UC Riverside. “This species is the expert at snow hunting.”

The researchers conducted a series of experiments in the forests of Manitoba, Canada. They digged holes next to those observed by the owls while hunting. They inserted speakers playing a variety of sounds. It includes high-frequency white noise and low-frequency recordings of burrowing voles (one of the owls’ favourite preys).

The experts discovered that low-frequency noises transmitted the best by analyzing the sounds emerging from the snow at six different depths. “The fact that low-frequency sound travels through snow explains the species’ facial disc. Because they have better low-frequency hearing with such a large disc,” Clark explained.

Furthermore, the analysis revealed that snow typically bends the voles’ sounds. It resulted in an “acoustic mirage” that could lead the owls astray. However, by hovering directly above their prey for a brief moment, these birds are able to compensate for the distortions caused by the snow. “The distance the sound has to travel from just overhead is shorter. There’s also less snow for the sound to travel through from that spot,” Clark says. This definitely aids owls in landing where they need to.”

Furthermore, the owls’ wings appear to dampen the sound of flying. It may allow them to better focus on the sounds of their prey. This discovery is of interest not only to owl experts, but also to engineers working on quieter flying machines.

“Airplane noise dropped dramatically between the 1940s and 1960s. But planes haven’t gotten much quieter since then.” “Understanding how these owls’ wings work could inspire new planes and drones that make less noise,” Clark concluded.

The findings were published in Proceedings of the Royal Society B: Biological Sciences.

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