Robin losing feathers

Hi all,

We have a pair of robins in the back yard that are very friendly (they will sometimes eat out of our hand). They raised two successful chicks a few weeks ago and now have at least one more from their next brood (we saw the chick for the first time today!). The one we think is the female appears to be completely fine. The other, presumed male, has been getting scruffier and scruffier over the last couple of months however and has started lose a lot of feathers from his chest and under the wings. He also seems to be breathing more heavily than the female, but otherwise is still very active and seems generally OK. We initially thought it might just be from the nesting effort but the feathers continue to get worse and now we think it might be mites or some other problem.

Here are some photos to show you what I mean:

One month ago: http://www.redyeti.net/rspb/Robin1.jpg

Today: http://www.redyeti.net/rspb/Robin2.jpg
Today: http://www.redyeti.net/rspb/Robin3.jpg
Today: http://www.redyeti.net/rspb/Robin4.jpg

We're wondering if there's anything we can do to help. Given he's so tame we can probably spray him with something occasionally, or put something in his food, water or waterbath if that might help?