An adult male sparrow sings its normal song:

An adult male sparrow sings its normal song:

a. if he hears the song during a sensitive period early in his life.
b. only when he hears a female bird singing.
c. if his own species' song is the first song he hears when young.
d. regardless of whether or not he has ever heard his species' song from another bird.

1 comment:

  1. a. if he hears the song during a sensitive period early in his life.

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