Last week four of us hiked the Redbank Trail near Lawsonham, Pennsylvania.  At our turnaround point we stopped at a picnic shelter and lean-to that had a new pit toilet restroom with a shiny green door.  As I left the restroom I noticed tooth marks on the doorknob.

Then I noticed tooth marks all along the bottom of the door and even at the top. See the red arrows.

The animal apparently propped its upper teeth against the edges and scraped with its bottom teeth.

It scraped the hinges.

And it ate the aluminum door jamb!

Who did this?  What Pennsylvania wild animal eats outhouses and chews metal?

The North American porcupine, Erethizon dorsatum.

Here’s one eating an outhouse in the Western Arctic National Parklands, posted by NPS on Flickr.

Porcupines eat outhouses?  Yup.  They crave salt and there’s a lot of salt in urine so they try to eat their way in.  There’s also salt on the doorknob from our sweaty hands.  I learned this from Matt Miller’s Cool Green Science blog.  Read more here!

Years ago Pennsylvania’s porcupines only lived north of I-80 but for more than a decade they’ve been expanding their range southward. When they reach Pittsburgh they’re going to find a lot of doorknobs.  😉

(door photos by Kate St. John. Porcupine-outhouse photo from Western Arctic National Parklands on Flicker, Creative Commons license; click on the image to see the original)

p.s. Porcupines are already south of Pittsburgh in the Appalachian Mountains of Maryland but they prefer to live in heavily forested areas.  I can’t imagine them moving into cities … but you never know.

p.p.s.  See the comments. Porcupines have been seen in the metro area. Uh oh!