the same species of bird will sing different songs in different regions. a good example of this is the currawong. this is an australia bird which is like a black and white crow. in the autumn, families get together in large flocks and do a lot of singing. currawongs from some areas sing much more complex songs than others. generally, currawongs from the blue mountains are the finest singers. the song of the currawong can be sung as a solo, but is often performed as a choir. one bird will take the lead and sing "warble-warble-warble-warble!" all the other birds will join in and sing "wooooooo!". when all the birds know the song, the choir will sing the "warble" part and the soloist will sing the "woo!". the song changes from year to year and from place to place.