Aviary sounds are the noises made by birds in captivity. The term 'aviary sounds' can refer to four distinct noises: TWEETS, cheeps, coos, and twees. TWEETS are short, high-pitched chirps made by small birds such as sparrows. Cheeps are similar to TWEETS but are slightly louder and more frequent. Coos are low-pitched, repetitive cooing noises made by doves and pigeons. Finally, twees are a combination of TWEETS and cheeps, usually made by finches.