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Bats are world-class echolocators, capable of navigating tight spaces and detecting minuscule insects. Photo: iStock / ivkuzmin

Bats are world-class echolocators, capable of navigating tight spaces and detecting minuscule insects. But smooth manmade structures can foil their sonar, a study published today in Science finds, potentially causing fatal collisions.

Why it matters: Bats are voracious eaters of insects, including many agricultural pests. They play a key role in keeping bug populations down. But urban noise pollution, habitat loss, pesticide use, wind farms and a fungal disease are causing bat populations to plummet. This study could explain why dead bats are frequently found near buildings.

What they did: Scientists at the Max Planck Institute for Ornithology created a rectangular flight tunnel, and placed a two metal plates in the tunnel, one vertically against the wall and one on the floor. Of the 21 greater mouse-eared bats flown in the tunnel, 19 touched the vertical plate at least once. None of the bats touched any other part of the tunnel. Then the scientists placed vertical plates near real bat colonies — and the wild bats crashed into them, too.

What's happening: The researchers think that the unnaturally smooth manmade surfaces reflect sound in a way that makes them almost undetectable. A bumpy surface would scatter sound in a way the bats could use. A smooth surface can redirect it away from the bats' ears, rendering the structure auditorily invisible.

Go deeper

2 hours ago - Health

U.S. surpasses 25 million COVID cases

A mass COVID-19 vaccination site at Dodger Stadium on Jan. 22 in Los Angeles, California. Photo: Mario Tama/Getty Images

The U.S has confirmed more than 25 million coronavirus cases, per Johns Hopkins data updated on Sunday.

The big picture: President Biden has said he expects the country's death toll to exceed 500,000 people by next month, as the rate of deaths due to the virus continues to escalate.

GOP implosion: Trump threats, payback

Spotted last week on a work van in Evansville, Ind. Photo: Sam Owens/The Evansville Courier & Press via Reuters

The GOP is getting torn apart by a spreading revolt against party leaders for failing to stand up for former President Trump and punish his critics.

Why it matters: Republican leaders suffered a nightmarish two months in Washington. Outside the nation’s capital, it's even worse.

Erica Pandey, author of @Work
6 hours ago - Economy & Business

The limits of Biden's plan to cancel student debt

Data: New York Fed Consumer Credit Panel/Equifax; Chart: Axios Visuals

There’s a growing consensus among Americans who want President Biden to cancel student debt — but addressing the ballooning debt burden is much more complicated than it seems.

Why it matters: Student debt is stopping millions of Americans from buying homes, buying cars and starting families. And the crisis is rapidly getting worse.

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