Finch Losing Cheek Plumage, WHY?? (pics included)

[mondo]

Recently my javas are losing the feathers around their face and cheek...
at first I thought they're only molting... until this morning I found once of them lost the whole plumage on their cheek!!

My canaries aren't losing any...
except for the male who curiously lost feathers on his nape (back of neck)
its the javas that are severe...

so what do you think happened? what can I do?

aviary specification:
200cm long x 120cm wide x 250cm tall
outdoors, planted, in the tropics but is currently rainy season
receives morning sunlight even though they don't automatically sunbathe
inhabitants are 7 java finch (3 pairs) and 2 canaries.

[Rox]

Do you ever see the Java's preening each other excessively, which could cause feather loss or perhaps even fighting? Some of my orange cheeks got into an argument and now the one bird is minus a patch of cheek feathers...

I would keep an eye on them. My first thought was mites but since none of your other birds are showing signs of feather loss, it can't be that

[mondo]

Rox

Yes I thought it was mites too...
unfortunately I can't keep a close eye on them, they're too timid around me.
this sunday I'll clean up the whole aviary and disinfect the whole area... if this problem still occurs I'll have to lure them into a cage and apply medicinal shower hehe

[MiaCarter]

mondo - Aw, poor guy.

Agreed with Rox.
Plucking could definitely be to blame. Finding the offender is the tough part, especially if they're skiddish and only pick on one. (Otherwise, if they pick on everyone, the culprit is the bird with perfect plumage! LOL)

It could be mites too.
With mites, there's almost always one who's more profoundly impacted than the others. (Usually the bird with the weakest immune system or the individual just happens to be super sensitive to whatever bug is ailing them.) So I wouldn't rule that out.
I'm sure it will be a 'time will tell' sort of thing, as it will only get worse with time if it's mites.

In some ways, mites are the better scenario! Much easier to cure than a plucker!