My zebra finch finally stopped biting completely!!!
I literally cried. After about 10 days of patient work, Ruby finally took a bath without freaking out today. I know it sounds small but if you've been through the bonding process with a nervous bird you know how HUGE this is. Never give up, it's so worth it.
I've had birds for 15 years and I've seen this many times. In my experience it usually comes down to a subtle environmental change you might not even notice.
So what I ended up doing was leaving the radio or TV on when I'm out — background noise helps. Within a few days there was a noticeable improvement. Definitely worth trying.
Anyone near Hamilton should check out the bird section at Pet Valu — surprisingly good for the area.
My zebra finch did this too! Turned out it was because of hormonal season — spring is brutal. Once I addressed that, everything went back to normal.