Bird Guy wrote in :

I'm wondering if the finches are just incredibly messy eaters, or are
these really the shells from the nijer seeds...

I see Juncos and Doves feeding from the ground under the feeder so the
finches apparently are dropping some. I suppose it's inevitable with
such tiny seeds. I've also seen sock-type feeders where the mesh is a
little too open and the seed falls out as the sock is jostled.

--
Tony Mortadella