0_Apprentice
I've heard the phrase bird vocalization before but I really don't know exactly what it means.
1_Wizard
Its not a common theme but it refers to bird calls and bird songs
0_Apprentice
Made by the birds themselves correct"
1_Wizard
Made by the bird themselves but I guess if a human could mimic it then it should count also. Its a bird sound that is melodious to human ears.