escapee wrote in
:

http://www.animaux.net/squirrel/

This is directly under the bird feeder, and only sunflower seeds are
in the feeders. We do have squirrels who are on the feeders
constantly and we don't chase them out. Is this squirrel feces?
Gauge the size based on the black oil sunflower seeds.

I would have guessed snake, but maybe squirrel, possum or raccoon.
Assuming you have to climb or fly to get to the feeder, I don't think
it's a bird because I don't think birds (having cloacae instead of
intestines) can excrete the fibrous portions of the shell (must
regurgitate if ingested ... probably didn't ingest). If they could I
would expect it to be watery. If it were a larger bird using gizard
stones to masticate the shells, I would expect the fibers to be less
intact.

Kind of odd to be right under the feeder. Looking the the bottom
pictures, unless it rained or something the suspect seems to just be
hanging out at the feeder, seeds go in crap comes out. Or maybe some
unreleated creature saw the pile of shells and decided it was a good
place to take a dump?

How to identify crap: http://memorias.ioc.fiocruz.br/98sup/30p.pdf