Preening gland

Cockatoos are one of the exceptions too. They don't have a preen gland. They have a fourth type of feather which continues to grow and breaks off creating the powder down which they keep their feathers clean and waterproof with. This is the white powder that you get on you when you play with a Cockatoo. These feathers are found underneath the wings around the hip area of the bird. All members of the cockatoo family have this. With a black cockatoo it is a black coloured dust, Galah's it is a grey colour. When a cockatoo has PBFD they do not develop these feathers and this is one of the main causes of the feather loss in them. A healthy Sulphur Crested Cockatoo always has a dusty appearance to their black beak. I have found it does not really develop the powder down properly until they are about 4 to 6 months of age. If a Sulphur older than this has a glossy black beak it has a problem with it's powder down or is not preening properly.

If I am wearing a dark coloured top and my Charlie gives me a cuddle I end up with white dust all down my front and sleeves.

Yes they have a preening gland but they also have the powder down. This extra feather is really interesting. It doesn't moult out when the bird moults, it continues to grow and breaks off creating the dust. Some of the Macaws don't have a preening gland and Amazons don't have one either.

It is the preening gland that also secretes Vitamin D which is produced from sunlight. It is UVA and UVB that is essential in the production of Vitamin D which allows the absorption of Calcium in the system. This is why birds require at least 15 minutes per day of natural sunlight. That is sun that has not passed through glass, plastic, perspex, fly screen or shade cloth. These all filter out the UVA and UVB and renders the sunlight basically useless.

The cockatoos have the gland but it is not used for preening the feathers and keeping them clean. I should have said in my previous post that they have one but don't use it as other birds do for preening.