Visual Sex Determination of African Grey Parrots

This is to be used only as a quick guide and is not intended to replace DNA or surgical sexing. Most aviculturists are aware of the males being darker in color. This can only be based on the fact both birds originated in the same region of Africa or they are chicks from the same clutch. Also, hens may have a gradual dark-to-light transition of gray from the neck to the belly, while males have a more uniform gray in the same area.

Importers used the under-tail coverts as the guide for sexing. This should not be termed "vent area" or "ventral feathers." The under-tail coverts are directly under the tail feathers and consist of about 10 feathers. Feathers of the hens will be edged in gray, while those of the males will be solid red. Males will occasionally have a hairline of white on the edge.

This is not for babies, and should be used for older greys, approx 18 months and older. The pictures are not great, but they will give you a reasonable idea of what to look for. The grey on the hens can be 1/16th of an inch to almost 1/3 of the feather. I have seen some hens where you could see the grey edge halfway across a room.
 

WING FEATHERS
Observe the birds from about 5 to 10 feet away while they are on a perch or hanging upside down from the cage top and flapping their wings. With this action, three bands of gray can be seen on the underside of the wing. The top band is the feathers making up the ventral antebrachial coverts. The band directly below is the feathers of the minor ventral wing coverts. The last band consists of the primary remiges. In a hen, these bands respectively "appear" gray, white and black. The male "appears" to have only two bands of gray and black. If you hold a bird, rather than viewing from 5 to 10 feet away and study this, your eyes "see" the actual different bands, and you cannot easily distinguish males from females. 
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