I think it's too synthetic - if you clip the Ro off
Roberta, it sounds like bird-a, but if you clip the Ro off
Robert there's no "bird" there. It's
Bert.
And also it's kinda unappealing. Birds have many negative connotations, also "bird" has been used as (slightly denigrating I believe) slang for woman.
Robin's not an option?
I think
Bear from
Roberto would be better than Bird from
Robert.
- mirfak