By Wendy Langhans

……This is Wendy Langhans, Outdoors correspondent for KHTS AM1220, on temporary assignment in Washington DC……

(I always wanted to say that.)

As any tourist knows, statues are a common sight in WashingtonDC. They’re everywhere you look. 

And it seems that wherever there are statues, there are pigeons.  Along with, of course, pigeon scat.  This relationship is the source of any numberof jokes, including the famous one, “Some days you’re the pigeon and some days you’rethe statue.”

But pigeon scat no longer seems so funny to me, not afterthe I-35 bridge collapse in Minneapolisin 2006.  A number of news articles,including one from Newsweek,identified pigeon scat as a potential “contributing factor” to that collapse,because “dried pigeon dung can cause corrosion and weaken metal."

To understand why pigeon scat is corrosive, we have to goback to high school biology class.  Mammals,including humans, produce ammonia when the amino acids in their proteins arebroken down.  Ammonia is highly toxic, soliver enzymes convert the ammonia into a slightly less poisonous urea, which isdiluted with water and excreted in urine. 

But egg-laying reptiles and birds, including pigeons,produce uric acid.  And acid, as we know,corrodes metal. 

So why are there two separate biochemical pathways?  What’s in it for the pigeon?

The pigeon benefits in two ways.  First, uric acid is relatively non-toxic,which protects the chick developing inside the egg.  Second, uric acid doesn’t need to be dilutedwith water, which helps the adult pigeon conserve water. 

These benefits come at a cost, though; it takes moremetabolic energy to produce uric acid than it does to produce urea.  This brings up a second reason why pigeonscat no longer seems so funny to me. Yesterday we visited the World War II memorial.  At the heart of this memorial is a wall ofgold stars.  Each star represents 100 U.S.servicemen and women who lost their lives during that conflict.  There were 4000 stars on that wall.  It reminded me that all benefits come at acost.  This is as true for people as itis for pigeons.

Saturday, September 20, 8:00 AM.  Early morning bird hike at TowsleyCanyon.

For maps and directions, click here.

Sponsored by the Mountains Recreation and ConservationAuthority.

Saturdays, September 13 and 27th, and every Wednesday, 8:00 am. Trail Maintenance Volunteers at TowsleyCanyon.

Come join our trail maintenance volunteers for camaraderieand a heart-thumping workout.  For moreinformation contact Steve Ioerger at661-291-1565.

You can listen to stories like this every Friday morning at 7:10 a.m. on "The Hike Report",brought to you by your hometown radio station KHTS (AM1220) and by theMountains Recreation and Conservation Authority.

For the complete MRCA hike and activity schedule and fortrail maps, click here or go to www.LAMountains.com.