Bridges as Habitat

April 16, 2009 § 3 Comments

Austin's Congress Avenue Bridge with Bats Emerging at Dusk

Austin's Congress Avenue Bridge with Bats Emerging at Dusk - Photo: Wikipedia

My friend Vicki returned recently from a trip to Austin, Texas. She told me about Austin’s Congress Avenue Bridge which houses the largest urban colony of bats – Mexican Free-tailed Bats to be exact. When the bridge was reconstructed in 1980, the design serendipitously ended up with a series of crevices on the underside of the bridge which just happen to be just the right size for these bats to roost in. The bridge is home to up to 1.5 million migratory bats during the summer. The bats eat lots of insects, which helps keep the mosquito populations in check. The city hosts bat festivals. Tourists come to view the bats from a specially built bat observation deck. There’s even a manual for bridge designers on how to make new bridges more bat-friendly. I want to go check it out.

Locally, I’ve seen cliff swallow nests on the bottom of bridges – at many times and in many places, including under the North Broadway Bridge by L.A. State Historic Park. In California, we have manuals on how to make bridges swallow-unfriendly. Truth be told, swallow-unfriendly is not so bad as it sounds – it’s actually a good idea to minimize adverse environmental impacts by keeping swallows from building under bridges where we plan to do construction work.

View of Sidewalk on Bridge - note the asphalt sidewalk repair in the foreground, and the uneven railing to the left.

View of Sidewalk on Bridge - note the asphalt sidewalk repair in the foreground, and the uneven railing to the left.

Diagramed Side View of Bridge.  Yellow Arrows show which way bridge shifted.  Red Arrow shows the gap where the bees were flying in and out.

Diagramed Side View of Bridge. Yellow Arrows show which way bridge shifted. Red Arrow shows the gap where the bees were flying in and out.

Side view of Bridge

Side view of Bridge

I was out exploring along a local creek last week and spotted a similar phenomenon here. I came across a bridge – which shall remain nameless – because I don’t really want the city to go out and “fix” it (but if you really want to check it out, you may be able to figure it out – or just ask me privately.) Part of the bridge had shifted and settled at some point, and, lo and behold, created bee habitat. A steady stream of bees were zooming in and out of a crevice. It’s L.A.’s own bee bridge!

So… all this got me thinking… Are there other examples creek freak’s asute readers are aware of where bridges serve as habitat – deliberately or inadvertently? Please post under comments if you’re aware of this – especially any that I can check out locally.

Is habitat something we could be factoring into future bridge designs? Could we build in various types of nooks and crannies for nests, perches, etc. I suspect that the engineers who design these bridges might not like lots of critters hanging out in their monuments… but if it turns out to be half as as successful as Austin, it could be a tourist attraction… and could begin to make up for a small portion of habitat we’ve lost along our woebegone waterways.

(Note: Nothing in this blog entry should be remotely construed as support for the demolition of historic bridges.)

Tagged: , ,

§ 3 Responses to Bridges as Habitat

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

What’s this?

You are currently reading Bridges as Habitat at L.A. Creek Freak.

meta

%d bloggers like this: