Breeding behaviour of Quaker Parrots

by Hazel
(Weston, NSW, Australia)

In the last few days my Quakers have started some very unusual behaviour. They are in a cage with a pair of Cockatiels, and in the past there have been no problems, although the male Quaker is the dominant bird.
Recently, he has started picking the female Cockatiel up by her crest, pulling feathers out. He gets very restless when I hold him, trying to fly around the room, etc.
To coincide with this, the female has started making a noise like a squeaky toy and bobbing her head, while claiming a shelf in the aviary previously claimed by the male Quaker as his territory.
Is this a mating ritual, or does she have something stuck in her throat? I'm new to this business!