Alexandrine parrot's strange behaviour

by Bec
(Gold Coast, Australia)

I have an alexandrine parrot that frequently displays a strange behaviour. Whilst sitting on his perch he holds one foot up next to his face (like he's holding an invisible phone) and makes the same short ascending noise over and over. He only ever does these two things at the same time and it is always exactly the same.

As he makes the noise he sort of runs his beak over his foot and pretend-nibbles it. He'll do this for ages and will often gradually get louder. He sounds content when he does it (never scared or distressed at all), but we don't know why he does it. Do you have any idea??