Song repertoire size in male song sparrows correlates with detour reaching, but not with other cognitive measures

Song learning is a cognitive task in which juvenile birds acquire, store and use information about adult song to shape their own song production. Comparative studies show that across bird species, performance on different cognitive tasks is usually positively correlated. If the same holds true within species, then the complexity of a male’s learned song ought to be correlated with other cognitive abilities. To test this hypothesis, we measured correlations between song repertoire size and cognitive performance in wild song sparrows, Melospiza melodia. Females prefer males with larger song repertoires in this species, and song repertoire size correlates with various fitness measures. We recorded males’ song repertoires in the field and tested these males in captivity on motor, colour association and reversal learning tasks, as well as on a detour-reaching task that measures inhibitory control. We found that individuals’ performance on the colour association task correlated positively with their performance on the reversal task, but performance did not correlate across the other learning tasks. Males with larger song repertoires were faster to solve the detour-reaching task, but performed worse on the reversal task than males with smaller song repertoires. Although our results suggest that song repertoire size does correlate with one measure of cognitive performance, more detailed song analyses and further cognitive tests are required to answer the questions raised by our findings.