Cultural transmission and its possible effect on urban acoustic adaptation of the great tit Parus major

Urban great tits (Parus major) sing with a higher minimum frequency than their forest conspecifics. Cultural processes may account at least in part for the song divergence in city birds as great tits learn their repertoire from conspecifics and switch to high pitch song types in presence of background noise. However, in small cities, this process of cultural divergence could be constrained because it is likely that these birds have a greater exchange of song types with the outside. We tested this prediction by recording great tit songs in a small city (Toledo, central Spain) and in a nearby forest. We found that background noise and the peak and the maximum frequency of songs were higher in the city but the minimum frequency did not differ. The pause length was also longer in forest birds. Seventy percent of the song types were shared between Toledo and the nearby forest. These results suggest that the small size of Toledo allows a homogenized cultural wealth, preventing the development of a high pitch song as observed in larger cities.