When Drake was sent away to boarding school, following the quake known as the Gotham Cataclysm, he was forced to give up the Redbird by 'selling' it to a disguised Alfred.
His resolution doesn't seem to come to a pass, as the Batcave still holds one or more Redbirds in storage along with other Batmobiles,[REF] and only a few days later Tim Drake is shown driving a new or a refurbished Redbird, identical to the previous one [REF] .