I'm just going to go through the head shots. The vents are mostly stretched out, which makes it hard to tell the shape, though the first and last ones looks male. The one titled "Lighter brown" looks like a pretty prominent bulge under the vent, which says male.
Head 1 - male
Head 2 - probably female
Head 3 - probably female
Head 4 - Need to see this one's chest as well, but probably female
Head 5 - male
Head 6 - unknown
Head 7 - probably female
Head 8 - not feather sexable
Head 9 - not feather sexable
Head 10 - not feather sexable