As Young Male Song Sparrows Move from the Plastic Phase

Multiple Choice

As young male song sparrows move from the plastic phase of song to the crystallized phase, they sometimes drop songs from their plastic song repertoire.

A) 8-10 songs may be dropped, leaving the bird with a crystallized repertoire of 1-3 songs.
B) Degree of song sharing with neighboring birds tends to be negatively correlated with male survival.
C) Dropped songs tend to match the songs of neighboring males less well than do retained songs.
D) Songs tend to be dropped randomly, thus neighboring birds end up having a distinctive repertoire.