Worm gathering aka grunting
 

http://www.plosone.org/article/info%...nal.pone.00034
72


"Recordings of vibrations generated by bait collectors and moles
suggest that ³worm grunters² unknowingly mimic digging moles. An
alternative possibility, that worms interpret vibrations as rain and
surface to avoid drowning is not supported."

More at above URL.

Bill

--
Garden in shade zone 5 S Jersey USA
"In no part of the constitution is more wisdom to be found,
than in the clause which confides the question of war or peace
to the legislature, and not to the executive department."

- James Madison