Do young birds fly if they live on ground?

. I have a large garden. I also have lots of bird feeders. I have a young blackbilack bird . She's been drinking and eating just living on the land. My boyfriend said it's a youngster and should fly soon. It's been a week now. Poor thing. Just had a Thunder storm. My neighbor said he will make a bird box for it so fingers crossed will keep dry in that if she wants