When my two Green Wings are surprised or alarmed by something they both say, "HI" in a rather loud high pitched voice. Is this unique or is it a Macaw quirk/trait? Anyone else out there that does this.

Must be a macaw thing, Mine all do it too.

Yup, macaw thing.

My GWs also make jungle/monkey sounds.

Yeah, the goons do it here, too. They also say it when they see themselves in the mirror, see another macaw on tv, or when I switch two at a time to one place from another, even though they weren't out of each other's sight at any time, and indeed, are usually riding on the same arm together!

They're insane, but I love 'em :-).