Why is my Budgie biting me??

Question
I've have my budgie Birdy (I know, not a very original name!!!) for nearly three years. He's very calm and gentle, and loves to be around people. He is a very intelligent bird and I had no problem training him to sit on my finger and come out of his cage to sit on my shoulder, but just a couple months ago he started biting!!! When I try to get him to sit on my finger in his cage he bites (very hard, and it hurts!!!), but when he's out of the cage he's fine. I have no idea why or how this happened!!! Please help me to get my non-biting budgie back!!!

Answer
The reason your Budgie is biting is probably because he does not feel comfortable sitting on your finger in his cage.
A cage is a Budgies home. It's their safe-place; somewhere they can go when they are scared, tired, hungry, thirsty, etc. When a Budgie's home in invaded, even if by a humand-friend, he can feel threatened.
It sounds to me like your bird is simply protecting his home. :)
Hope this helps, and good luck with Birdy!