Why is new bird biting me

[cutetreee]

I got this hand raised 2 month old cockatiel yesterday. All yesterday she stepped up and seemed friendly. Now, she hisses at my hand and has done multiple bites (no pain) She doesn't like to step up anymore either.

Why is she being aggressive now?

 

[Shezbug]

She will be overwhelmed and terrified- she is now in a whole new environment than she has known and she is now with a new person and has new sounds etc. Give her time to settle in by not pressuring her to interact with you with step ups and such. Just leave her be in her cage and sit near her (without staring at her) and chat to her, sing to her, just be there.
Her "aggression" is her way of communicating with you- she is telling you she does not want you to be so close to her as she feels threatened.