When it comes to learning songs, female birds may be quicker studies, but males can develop the ditties on their own. According to a report published today in the journal Nature, female cardinals learn the same number of songs as males in less than a third of the time. Yet whereas males can master the avian arias without any tutoring, females cannot.
Baby birds pick up songs by listening to the adults around them. Among temperate species, usually only the males sing. The northern cardinal Cardinalis cardinalis, however, is an exception to this rule. Ayako Yamaguchi of the University of California at Davis thus decided to explore whether patterns of song acquisition differ between the sexes in these birds. Using tape-recorded cardinal tunes, Yamaguchi tutored 15 females and 11 males over a one-year period. She found that females stopped picking up new songs after about 70 days. Males, in contrast, kept learning them until around seven months of age. In addition, Yamaguchi observed that females raised in isolation rarely sang. Moreover, when they did, their songs exhibited poor acoustic quality. But isolated males, she reports, "developed improvised song types ... similar to normal cardinal songs."
Exactly why such differences in learning patterns exist remains unclear. Because adult cardinal songs exist as different dialects in different geographic regions, dispersing juvenile birds may land in a population with a foreign dialect. The male pattern, Yamaguchi notes, "allows him to match his song types with those of his neighbors, even when he settles into a new population." A female, on the other hand, preserves her natal dialect. "Song matching may be important for male cardinals in the context of establishing territories, as in other species," the author writes, "but evidently is not for females, for reasons yet to be identified."