Not far from the Arizona Biltmore, there's a "bat cave" where more than 20,000 bats live. Every year, beginning in May and lasting through September, bats migrate to the area to give birth to their young. Around sunset each evening, the bats can be seen flying out of the tunnel in large groups, hunting for bugs. According to the Arizona Department of Game and Fish's Bat Conservation and Management program, there are two types of bats in the cave: Mexican free-tailed bats, and western pipistrelles. People can learn more about them each month during the summer, when the Game and Fish Department holds bat workshops near the cave. The bat cave is actually part of a Maricopa County Flood Control ditch, and getting there requires parking near 40th Street and Camelback Road, then walking along the north side of the Arizona Canal for about half a mile. The bat cave entrance is north of the canal and is marked with signs.