The nightly emergence of millions of bats from the Ann Richards Bridge on Congress Avenue is a popular attraction in Austin during the summer. While many will tell you all those bats all fly south to Mexico for the winter and leave the bridge abandoned, it’s a little more complicated than that.
“You know that was kind of a surprise. There was a really large emergence from Congress Avenue bridge and apparently they came out when there was still a little light in the sky,” says Diane Odegard of the conservation group Bats International.
The bats don’t all leave for the winter, Odegard says, adding that bat colonies move with a little more fluidity than we might think, making them really hard to track. Some of our bridge bats could simply stick around through the colder months.
Other bats who summer farther North actually come to Central Texas to winter. They sometimes make use of the bridge and emerge when it’s warm enough to find bugs.
“They can go into a torpor state which is kind of like a hibernation state but they can only do it for 10 days to two weeks without food and water," she says. "So, if it’s really cold for very much longer, than that they can get into trouble in our climate.”
So, bats are with us year-round, but it’s just best to see them in the summer when there are both more of them and more sunlight to see them.