This is also the current tag in the MA and Northern New England games.
Between engine trouble and a flat tire, I ran into a lot of trouble on this one, so was not able to move it as far as I would've liked. Anyway, a few bike lengths north of my bike in the tag shot you'll find a small section of the wall that has collapsed:
Egg is hiding here, in the collapsed section:
I helped him with a little more cover from the elements by piling another rock against the one he's hiding under:
and left a clue to make him a little easier to find: