My dad owns a cockatoo named Harry and sometimes in the middle of the night he will scream and wake him up so my dad runs down stairs to calm him down and it works. Sometimes he will be whispering in his cage at 3 am or something like that. He also yelled Hello a few times while nobody was down there. We did figure out that the apartment that my dad lives at is very "active" if you know what i mean. The other bird my dad owns(Brady a cockatiel) doesnt do this. What do you think is going on?