Chinese culture connects deeply with nature. Even in tiny apartments in big cities, you'll often find a pet singing bird. Early in the morning people will take their birds to the park, where the birds hang in trees and sing to each other. Exercise and companionship for pet and owner ! Afterwards, people congregate to the teahouse where the birds hang in windows, singing away. All these activities are but a substitute for observing birds in nature - as is the recreation of birdsong in music. Here is a clip showing Du Ciwen, playing birdsong on short Chinese transverse bamboo flute. Notice how each segment is short and varied, the sudden leaps of tone, even the hollow thudding timbres. Nature isn't always "beautiful". Note how Prof Du varies tempo and direction. Messiaen would have loved this !