NOTE: The Arizona Sonora Desert Museum no longer send docents out on Thursdays in the summer but the bats still come every summer, roughly June - September.
I had heard rumors that thousands of bats live under the North Campbell Street bridge (just south of River) each summer and that they take flight at sundown in the summer. This is a fun an educational event for the whole family. There is a similar colony of bats under the Pantano Bridge. Occasionally Pima County Parks and Recreation will host docent led educational event.
At Campbell and River you can park at the southwest corner of St. Philips Plaza near what was Scordato's, (they have moved) or across the bridge and walk across the wash if there is no water in it. OR you can ride your bikes. The Loop is right there.
Here are a few photos I took of the event.
Just before sundown, a few scout bats flew out from under the bridge.
Then, all of a sudden, as if on queue, thousands of bats take flight right about sunset.
My advice. Make an evening of it! Take the kids. Take a picnic or visit one of the restaurants near St. Philip's Plaza after the event.
And if you are feeling really adventurous, arrange to go to Ruby and spend the night camping. Watch the bats fly out of the mine shaft. Be sure to call in advance. The website is rather dated.