I realize that it’s quails, not partridges, that have a feather tuft, but this is the mental image I have of partridges in pear trees. To make the tuft, after the last decrease round, k2tog across (3sts remaining). Work these 3 stitches as i-cord for 1”. Break yarn. Pull yarn tail through stitches and down center or i-cord. This will make the i-cord shorter and a bit wider.
For the beak, cast on 5 sts, knit 1 row, and follow decreases from pattern for the wings/tail.
For tail, cast on 6 sts, knit 1 row, and follow decreases from pattern.