The Bourkes Parakeet can be visually sexed.
The female Bourkes Parakeet is smaller than the male and has a white brow above the nares, a white wing stripe, and are generally duller in color than the males.
The males are larger and have a blue band of feathers above the nares, blue along the bend of their wing, paler blue on the flanks, side of their rump, and under thair tail.
Females may have blue above the nares but it’s much duller.
Mature males have a blue crown on their forehead and brighter blue on their wings.
Hens and juvenile Bourkes parrots have a full grey head while the hen can be distinguised from the juvenile by their more pink coloration.
Adolescent Bourkes have duller coloration and lack the blue band above the nares.