Interstate 35 Bat Colony
McNeil Road Overpass, Round Rock

Last updated September 21, 2001

Also see: Interstate 35 Main Page

Austin's large bat colony under the Congress Avenue Bridge downtown is well known. According to the Austin-American Statesman, it has up to 1.5 million Mexican free-tailed bats. What is less known is the bat colony underneath the Interstate 35 overpass at McNeil Road in Round Rock, about 15 miles north of Austin. It is smaller than the Congress Avenue colony, but still a good-sized colony. I don't know how long this colony has inhabited Interstate 35. Even during the day, a loud din of bat calls can be heard underneath the overpass. There is an accumulation of guano on the ground, with the associated smell.

The bats did not leave for their nightly feeding until after dusk, making them very difficult to photograph. But I did manage to get a few decent shots, as shown below. In case you're wondering, the bats do like to relieve themselves when they become airborn. I felt a lot of small droplets and pellets hitting me as I was taking the photos. A shower was on the agenda when I arrived home.

Photos taken 16-September-2001 and 20-September-2001

This mild-mannered overpass on Interstate 35 in Round Rock, Texas, is harboring the bat colony.

Signs around the overpass warn against handling downed bats. I didn't see any downed bats or carcasses on my 2 visits to the overpass. Maybe TxDOT does daily cleanup.

The bats live in the narrow spaces between the precast concrete beams.

When the time comes for the nightly feeding, there are thousands of bats in the air. This view shows the edge of the overpass with the bats on their way.

Another wide view.

A closer view of some bats underneath the overpass.

Another view underneath the overpass.