Birds either shift song frequency up or abandon noisy areas to escape traffic masking

Evidence

The grey shrike-thrush sings at a higher frequency in the presence of traffic noise. The other species, which normally sings at a higher frequency than the first species, seems to not change its acoustic pattern but to appear less frequently in areas with high traffic noise. These different effects on these two species demonstrate two different strategies to cope with traffic noise: the first can raise the frequency to avoid the masking of the lower frequency of traffic noise, and the second species, which already has a song emitted at high frequency and cannot further accommodate the frequency, reacts by avoiding louder conditions. Birds have been shown to sing at a higher pitch, sing louder (Lombard effect), and change the time of day for singing to reduce the masking effect of traffic. — Almo Farina, Soundscape Ecology, 1366

Categorization

• XREF: Builds on ch25’s Lombard-effect claim and on the existing ‘Lombard effect’ curations in earlier chapters. — connects to: Species shift calls to ultrasonic frequencies to escape constant noise masking — Almo Farina, Soundscape Ecology: Principles,…, 1288; Geophony from wind and anthrophony from traffic both suppress animal acoustic communication — Almo Farina, Soundscape Ecology: Principles,…, 127; Urban birds shift their songs to higher pitches to escape traffic noise — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 941 (+2 more)
• DEFINE: Concretely illustrates the two coping strategies — frequency shifting vs spatial avoidance — that recur throughout acoustic ecology.

Broader Connections

• Urban birds shift their songs to higher pitches to escape traffic noise #corroborates (0.92) — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 941
• Traffic noise permanently raises song tonality in red-winged blackbirds #exemplifies (0.85) — Almo Farina, Soundscape Ecology, 1384