New bird

Hello! Yesterday I got this little guy, and I’d like some advice! The attendant from the store told us we should let him inside the cage for 3 days and to not let him leave it. Is that really recommended?

He seems really, really frightened! Should we let him be or try to interact with him? He runs away whenever we get close

We’ve been thinking about at what age we should get him a little partner too (he’s 3 months), and if it’d better if it were a female or male.