What is the sound of birds and what does it sound like?

Birds sing like melodious flutes and melodious songs.

Birds' calls and songs mean that most birds can sing in various tones and rhythms. Ostrich and vulture's singing tube is very simple, quail chicken has a complete singing tube, but it lacks the singing muscle of diaphragm, so it is impossible to adjust the singing. Subsongbirds have 2 ~ 3 pairs of vocal muscles, and songbirds have 4 ~ 5 pairs of vocal muscles, which make the semilunar vocal membrane in the vocal tube gyrate and vibrate, and make different songs. All kinds of birds have unique songs, and the songs of the same bird are different between males and females, between adults and young birds, and between breeding and non-breeding periods.