October 15, 2005

Austin's Twilight Show

A couple of weeks ago, while in Austin, I finally saw one of the most impressive bat shows around. From March to early November, over a million Mexican free-tailed bats roost by day in the slats under the Congress Avenue Bridge and at twilight they stream out in huge clouds, ready to hunt for insects to eat throughout the night. Bats Under Bridge When the bats first showed up, people in Austin were not too pleased, convinced that bats were dangerous creatures of the night. Fortunately, as they learned more about their summer visitors, Austinites welcomed the bats and learned that they could be quite a tourist attraction.

A Little History: When engineers reconstructed downtown Austin's Congress Avenue Bridge in 1980 they had no idea that new crevices beneath the bridge would make an ideal bat roost. Although bats had lived there for years, it was headline news when they suddenly began moving in by the thousands. Reacting in fear and ignorance, many people petitioned to have the bat colony eradicated.

About that time, BCI stepped in and told Austinites the surprising truth: that bats are gentle and incredibly sophisticated animals; that bat-watchers have nothing to fear if they don't try to handle bats; and that on the nightly flights out from under the bridge, the Austin bats eat from 10,000 to 30,000 pounds of insects, including agricultural pests.

As the city came to appreciate its bats, the population under the Congress Avenue Bridge grew to be the largest urban bat colony in North America. With up to 1.5 million bats spiraling into the summer skies, Austin now has one of the most unusual and fascinating tourist attractions anywhere. The Austin American-Statesman created the Statesman Bat Observation Center adjacent to the Congress Bridge, giving visitors a dedicated area to view the nightly emergence. It is estimated that more than 100,000 people visit the bridge to witness the bat flight, generating eight million dollars in tourism revenue annually.

Last weekend, DarkSyde had a most excellent post on bats and what we can learn from them. Evidently, they are such surprising creatures that the Creationists use them as evidence that evolution is a questionable science.

Because of recent fossil finds shedding light on the cetacean evolutionary tree, creationists have switched from using whales as an exemplar of Darwinian ignoratum, to using bats. If the goal is to confuse adoring fundie audiences while subconsciously playing on a repellent mythological sub-theme, bats are an excellent choice. The evolutionary origin of Chiroptera remains a topic of great interest and greater mystery. Adding to the confusion, there is reasonably good evidence, albeit controversial, that megabats and microbats developed flight independently of one another millions of years apart, but both from a recent common ancestral clade. Muddying that picture even further, it turns out that several species of what were previously called microbats actually descend from fruit bats.

Austin is lucky to have attracted these voracious insectivorious bats to their town. Do drop by to see the show next time you are in Austin.

Posted by Mary at October 15, 2005 03:46 PM | Science | Technorati links |

What an interesting community.

Posted by: Thomas Ware at October 15, 2005 05:40 PM

I used to paddle my kayak under the bridge at dusk. Freaking cool and creepy.

If you go back to Austin, visit one of the canoe or kayak rental sites along Town Lake and paddle yourself under the bridge to see them from the water.

Aside from a strange and creepy view of the bats, it's a lovely and incredibly accessible paddle, especially at dusk.

-- Lupe, now in Seattle.

Posted by: lupe at October 15, 2005 10:00 PM

Thanks for the post!

A couple of years ago I was visiting San Antonio. Around dusk I happened to be walking with a friend under a large structure (a huge sign attached to an old, probably empty, building) and a similar bat show began with the bats pouring out of the bottom of the sign.

We found ourselves in a sea of bats. Freaky at first, but fascinating nonetheless.

Posted by: Darryl at October 15, 2005 11:55 PM