Hey, what's the deal with those strange bird noises under Camden Bridge?

A reader encounters strange, tropical bird noises with no strange, tropical birds in sight.

A reader encounters strange, tropical bird noises with no strange, tropical birds in sight. Tim Kiser, Wikipedia

Hey, What’s the Deal With... is a new City Pages series that asks: Hey, what’s the deal with that?

We’re all about putting mysteries to rest, no matter how small. So it gave us no shortage of delight when a tipster told us about weird noises they encountered while walking under the Camden Bridge in Minneapolis, which spans the Mississippi and connects 37th Avenue Northeast and 42nd Avenue North.

“I noticed a lot of bird sounds,” the tipster said. “Didn’t see any birds around.”

It gets weirder. Some of those bird sounds were tropical-sounding, like the shriek of a parrot. There was a “beeping” sound too. The underside of Camden Bridge is either full of invisible macaws, or something else is at play here. We decided to investigate.

It’s not every day you call the city and ask if they have a bridge that makes bird noises, but when you do, expect a lot of pregnant pauses on the other end. Receptionists were (understandably) confused, and the Minnesota Department of Transportation’s Bridge Office (yes, there is a Bridge Office) referred us to a pair of engineers, neither of whom got back to us.

Luckily, city of Minneapolis Spokesperson Casper Hill helped us out. The good news: Our Facebook tipster is not losing their senses. There really are disembodied bird sounds under the bridge. As to whether they’re “tropical” though…

“That is an interesting way to describe it,” he says.

The noise is coming from a speaker attached to the underside of the bridge. It pipes in the sound of “predators and frightened birds,” as Hill put it, in order to ward off pigeons. There’s a similar device hard at work on the St. Anthony Parkway Bridge.

Pigeons, as it turns out, are an infrastructure problem. Pigeon guano, besides being gross, is slightly acidic. Over the years, if enough pigeons use a specific bridge as a house or a toilet—or both—they can rust the beams.

Which means the caretakers of bridges nationwide spend a lot of time either cleaning up decades of built-up guano, or dreaming up new, inventive ways to keep the birds away. That can mean installing spikes or nets to keep them from sitting comfortably on flat surfaces, trapping them, or simply scaring them off by playing sounds they hate.

So the next time you hear some weird bird sounds under a bridge, but there are no birds in sight, rest assured—everything is working exactly as it should.

In Hey, What’s the Deal With... we’re tackling everyday oddities, random curiosities, and what-the-actual-fuck mysteries about life in the Twin Cities. Got a pressing but somewhat trivial Q about something you saw, heard, or thought about while stuck in traffic? Email [email protected].

Previously in Hey, What's the Deal With...