In Phoenix on Sunday, the National Weather Service's radar captured what first appears to be rain clouds blooming over the Valley of the Sun. Turns out, it was likely a large colony of Mexican free-tailed bats on the move. From WSMV:
"That doesn't look like a normal shower, the way everything is sort of fanning out. They don't really have a uniform direction. That's usually your clue initially that it's probably animals flying around," said NWS meteorologist Sean Benedict[…]
The radar likely shows the bats coming out of a cave, a tunnel, or a bridge and then dispersing to find bugs to eat across the city. There are 28 bat species that hang around in Arizona, but of course, they're not always easy to see in the dark. That's why radar can be so helpful for scientists to track them. [Arizona Game and Fish Department biologist Angie] McIntire said she would love a collaboration of sorts to combine the Game and Fish Department's knowledge of bats with the National Weather Service's expertise of radar.