Clouds of bats flying over Phoenix captured on weather radar, meteorologists say

That wasn’t clouds or rain filling up National Weather Service radar over Phoenix, Arizona, on Sunday evening, meteorologists wrote on Twitter.

It wasn’t aliens, chupacabras or gender reveal parties gone awry, either.

“Bats! Specifically they are probably thousands of Mexican free-tail bats that migrate here for the summer,” NWS meteorologists wrote on Twitter.

Radar images posted to Twitter and Facebook by the Phoenix NWS office show clouds of bats blossoming out over the city at dusk.

“That doesn’t look like a normal shower, the way everything is sort of fanning out,” said NWS meteorologist Sean Benedict, KTVK reported. “They don’t really have a uniform direction. That’s usually your clue initially that it’s probably animals flying around.”

“We actually detect them most evenings through the summer,” NWS meteorologists wrote on Facebook. Weather radar doesn’t show individual bats or small numbers of bats, but it can pick up immense clouds of the flying mammals as they emerge from caves or tunnels.

Biologist Angie McIntire with the Arizona Game & Fish Department agreed with the NWS assessment, saying they are likely Mexican free-tailed bats, according to KVTK.

Mexican free-tailed bats, which are about the size of two thumbs put together, can reach airspeeds of up to 99 mph, Bat Conservation International says.

They can reach altitudes of up to 10,000 feet as they forage nightly for insects and gather in colonies of hundreds of thousands of bats, the organization says.

The largest-known colony of Mexican free-tailed bats contains 20 million bats, according to Bat Conservation International.

“Mexican free-tail bats would probably be going to Mexico to spend the winter,” McIntire said, KTVK reported. “Some of them stay over winter here in Phoenix.”

This story was originally published September 15, 2020 at 9:56 AM with the headline "Clouds of bats flying over Phoenix captured on weather radar, meteorologists say."