Some interesting toothwork on trail markers in North Alabama: Almost every metal sign on the trails at the Land Trust of North Alabama’s Monte Sano Preserve is incised with dozens or hundreds of striations.
The artist? Gray or fox squirrels? We saw plenty of grays. Perhaps night-working flying squirrels? I’d welcome your thoughts!
Rodent incisors grow continually through their lives, a self-renewing mechanism necessitated by the walnut cases, seed husks, and other rock-like coatings with which plants so inconveniently wrap their progeny. These ever-growing teeth need continual shaping and sharpening. Might this be the reason for the rodents’ attention to the trail markers? I’ve seen similar markings on horn and bone. But these biological remnants are calcium-rich, unlike aluminum trail signs. It would be interesting to hang some files in the woods and watch the evolution of dentistry.
David George Haskell 
I love what your eyes show me.
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I wonder what’s in that paint. :)
Titanium dioxide…but no calcium?
I’ve seen those same markings at the State Botanical Garden of Georgia in Athens
Interesting. I wonder if GA and AL squirrels are particularly prone to do this?
“files” may have probs w/ethics committee?
No doubt!
How about a couple of cameras to record the nightly dental routine?
Good idea! Unfortunately these trails are some distance away and I visited only briefly. A good project for the future.
I saw these same markings on aluminum tags at Dr. Evans’ chestnut oak study plot in Sewanee. Some of the tags were completely gone or had a small scrap left where the nail held the tag on the tree.
Any idea who dunnit? I know deer will rip at dangling objects.
I’ve observed this mammalian vandalism on Corps of Engineers boundary markers around Percy Priest Lake near Nashville.
Biodiversity these days has no respect for authority.