Each of the pictures is a bird whose name is two words, with the first an adjective and the second a generic term for a bird. The music (birdsong) tells you how to modify the adjective. First, the quarter notes indicate which letters are removed (C=first letter, D=second letter, etc.). Then, the longer note (which is played at the same time as the quarter notes) indicates what to replace these letters with. Specifically, replace the removed letters with the solfège name of the note (C=do, D=re, etc.). Thus, including the example (the first row in the table), the birds and transformations are:
Reading the indicated letters from the transformed words spells out CARRIER. This goes with the last image, of a pigeon, to form the bird carrier pigeon. Applying the associated music transformation to "carrier" gives CAREER, the answer.