I have parakeets and they like to shake their head up and down a lot what that means are they mating?

Answer 1

This is a affection behavior. (not a technical term). But they will bob their heads up and down, and then regurgitate food and feed it to their mate. I have had breeding pairs do this to each other but also just cage mates. I have had males do this to each other. Even solitary parkeets with a mirror will do this to their reflection and regurgitate on the mirror.

Answer 2

Generally it means that your bird is happy. They bob their heads up and down as a sign of affection or simply to play...mine often does it when I have music playing because he likes to 'dance'. ;p