Here's a fun fact: Arizona is home to 28 species of bats, second in the nation to Texas. They're spread all over the state, but one colony of Mexican free-tailed bats has claimed as its summer home a flood-control tunnel near Camelback and 40th Street. The colony reportedly numbers 10,000-20,000 bats, which leave the tunnel nightly in search of some tasty insects. To witness this exodus, park near the intersection before sunset and start following the canal at the northwest corner of the intersection. Walk on the right side of the canal, and when you see a path heading off to your right, follow it until you arrive at the tunnel. You'll need to be quiet while you wait, as the bats don't like a lot of commotion. But eventually, you'll be rewarded with the sight of thousands of bats heading out for dinner. Don't worry, the bats aren't interested in humans and we've never seen a bat run into a spectator. As you head back to your car, keep your eyes peeled for bats picking off bugs from the surface of the canal.