Crazy canary

We've had Tango the canary for a few months now, he is very much a part of the family. We love his singing and funny antics, but this particular one has us stumped. Instead of hopping into his bath and splashing about like a normal bird, he lies flat in it and doesn't move for hours on end. There's no rhyme or reason to him doing this, it doesn't matter if the sun is in or out. We asked his former owners but they didn't see him do it while they had him. I've Googled this strange act, but to no avail. If anyone out there in blip land can help I'd be very grateful.