When nestling House Finches defecate, the feces are contained in a membranous sac, as in most birds. The parents eat the fecal sacs of the nestlings for about the first five days. In most songbird species, when the parents stop eating the sacs, they carry the sacs away and dispose of them. But House Finch parents do not remove them, and the sacs accumulate around the rim of the nest. Learn More...