This is something I've never seen in a zoo or park before, and I've seen lots of Satin Bowerbirds! Immature males look like females initially (a green coloured bird with a darker beak). They start developing the blue plumage in their third or fourth year, and it can take until their seventh year before they are completely dark blue. I'm guessing this bird is probably in his fifth or sixth year.
August 2009