When I got home, I Googled the caterpillar for an I.D. I think it was a Luna Moth caterpillar.
The color should have been a clue, but I have seen some bright green hornworm caterpillars in recent years. Never having seen a Luna Moth caterpillar before, I took a photo with my iPhone and let it be.
Should I have moved it off the post, made of composite materials, or left it be? It is a Luna Moth caterpillar, isn't it?
The Nature Conservancy installed the sign last year; caterpillar arrived this month.
More on High Mountain here.