bird croaking

by Olivia
(maryland)

Hi, i've got a 6 year old parakeet budgie. for the last few years he's taken on a worrisome habit. when he's alone or left to be quiet, he'll start this strange croaking noise. he seems to be filling himself up with air, because his upper chest will distend grossly outwards and it looks very strange. he lets the air out if you disturb him.

i've been concerned about it and whether its a health problem, or if its possibly something he does because he's bored or picking up some OCD behavior. i'm just afraid its reflecting some respiratory problem or blockages farther down. he's pretty active otherwise, and while he's not fit and gets winded easily he is always bright and responsive. thanks for any advise.