Birdsongs keep pace with city life: changes in song over time in an urban songbird affects communication
Publication Type: |
Journal Article |
Year of Publication: |
2012 |
Authors: |
D.A. Luther, E.P. Derryberry |
Publication/Journal: |
Animal Behaviour |
Keywords: |
ambient noise, birdsong, communication, cultural evolution, signal salience, urban |
ISBN: |
00033472 |
Abstract:
Animals in urban environments often must adjust their vocalizations to be heard over the din of
anthropogenic ambient noise. Most studies of this process use current comparisons of environments that
vary in ambient noise; here, we evaluate over time the effects of the urban environment on signal
structure and salience. We show that white-crowned sparrow, Zonotrichia leucophrys, song increased in
minimum frequency between 1969 and 2005 in San Francisco, California, U.S.A., coincident with rising
levels of traffic noise. A higher minimum frequency is less likely to be masked by low-frequency ambient
noise and thus is more likely to be effective as a communication signal. To test whether this change in
song affects receiver response, we presented territorial males current (2005) and historical (1969) local
songs. Males responded more strongly to current than to historical songs, suggesting that current songs
communicate more effectively in the current local environment. The results suggest that behavioural
adjustment to anthropogenic ambient noise over time can affect cultural evolution and communication.