I'm wondering though, if this vocal behaviour would rub off on the new birdie.
...Does Ducky ever *harmonize* with Sam?
Nope. Not in the least bit. Sam's about 6 years old, hormonal right now. He's the one who's cockatiel "screams" (good grief, I can't even call the sounds he makes screaming compared to my other birds) are grating on our nerves.
Ducky doesn't seem responsive in any manner to Sam's noises. He doesn't mimic them, he doesn't join in on them. In the mornings it's very common to hear Sam going on and on and on. . . and there's not a peep out of Ducky.
Sam's boy sounds are severely reduced when I take him away from their cage. I have cages and play stands everywhere. Sam spends his days all over the house and that change of scenery really reduces his boy obsessions. I also have outside aviaries and flight cages so if the weather's nice he spends days out there. I change it up every day so he seems stimulated other than being occupied with his male thoughts.
Here's my noise experience from mixing different species (cockatoos, conures, tiels, etc.) - They don't seem to feed off each other, noise wise, unless they're the same or very similar species ie - sun conure will feed off a jenday, a jenday will not feed off a cockatoo. Exception is generally a warning call - like someone coming to the door. One goes off, the flock goes off.
Oh - I wanted to clarify because I know I posted conflicting info. I had indicated to Kaylayluh that in a petstore they're feeding off the other birds - energy. I want to clarify that it's about the energy that they seem to feed off of. Not the other birds actual vocalizations. Usually in a petshop it's a high stress environment so all the birds are screaming. It's that anxiety and energy that they're feeding off of. Same with the mixed flock going off with warning calls - it's the energy of something to be alarmed about. The energy seems it can be any species - birds, people, dogs. I've had hyper dogs and when they race around it causes the birds to scream.