Do you see him plucking his feathers? He looks to be in GREAT condition, and there should be feathers in that spot. Didn't you say he is going through a heavy molt? Hopefully he'll grow them back, but if not, don't worry, he's still as handsome as ever.
My GW looks like that, except a little worse. He almost has no feathers only on the inside of his legs. Outside of that, he hasn't plucked anywhere else.
Just asking, does he stick his leg through the bars of his cage ever? You know to grab a treat or play around or something? My dads cockatoo has a small bare patch on his one leg similar in appearance to what Rio has for years. It's not plucking or molting, it's his love of reaching his little leg though the bars of his cage to grab treats or unsuspecting passerby's clothes:09: That has literally worn his feathers off in that area. It's only on the one leg because that's his dominate foot (kind of like we're either right or left handed, parrots have a dominate foot).
Yes giradia is a concern like above post have mentioned! Please do have him tested and do the fecal sample testing! I've dealt with it before with one of the rescued dog and it took me months to get rid of it.
Symptoms: A Giardia infection in psittacine birds may be asymptomatic or the birds may exhibit signs of weight loss, bulky or loose foul-smelling stools, vomiting, diarrhea, anorexia, depression, and recurring yeast infections.
Dry skin and feather picking is typical in budgerigars and cockatiels suffering from Giardiosis.