title: Bird song and anthropogenic noise: vocal constraints may explain why birds sing higher-frequency songs in cities.
abstract: When animals live in cities, they have to adjust their behaviour and life histories to novel environments. Noise pollution puts a severe constraint on vocal communication by interfering with the detection of acoustic signals. Recent studies show that city birds sing higher-frequency songs than their conspecifics in non-urban habitats. This has been interpreted as an adaptation to counteract masking by traffic noise. However, this notion is debated, for the observed frequency shifts seem to be less efficient at mitigating noise than singing louder, and it has been suggested that city birds might use particularly high-frequency song elements because they can be produced at higher amplitudes. Here, we present the first phonetogram for a songbird, which shows that frequency and amplitude are strongly positively correlated in the common blackbird (Turdus merula), a successful urban colonizer. Moreover, city blackbirds preferentially sang higher-frequency elements that can be produced at higher intensities and, at the same time, happen to be less masked in low-frequency traffic noise.
authors.affiliation: Communication and Social Behaviour Group, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany. enemeth@orn.mpg.de
authors.forename: Erwin
authors.initials: E
authors.lastname: Nemeth
authors.forename: Nadia
authors.initials: N
authors.lastname: Pieretti
authors.forename: Sue Anne
authors.initials: SA
authors.lastname: Zollinger
authors.forename: Nicole
authors.initials: N
authors.lastname: Geberzahn
authors.forename: Jesko
authors.initials: J
authors.lastname: Partecke
authors.forename: Ana Catarina
authors.initials: AC
authors.lastname: Miranda
authors.forename: Henrik
authors.initials: H
authors.lastname: Brumm
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000819:Animal Communication; D000818:Animals; D002947:Cities; D020308:Songbirds / Q000502:physiology*; D013018:Sound Spectrography; D014828:Vocalization, Animal / Q000502:physiology*