Data from: Aircraft sound exposure leads to song frequency decline and elevated aggression in wild chiffchaffs

1. The ubiquitous anthropogenic low-frequency noise impedes communication
by masking animal signals. To overcome this communication barrier, animals
may increase the frequency, amplitude and delivery rate of their acoustic
signals, making them more easily heard. However, a direct impact of
intermittent, high-level aircraft noise on birds’ behaviour living close
to a runway has not been studies in detail. 2. We recorded common
chiffchaffs Phylloscopus collybita songs near two airports and nearby
control areas, and we measured sound levels in their territories at
Manchester airport. The song recordings were made in between aircraft
movements, when ambient sound levels were similar between airport and
control populations. We also conducted playback experiments at the airport
and a control population to test the salience of airport, and control
population specific songs. 3. In contrast to the general pattern of
increased song frequency in noisy areas, we show that common chiffchaffs
at airports show a negative relationship between noise exposure level and
song frequency. 4. Experimental data show that chiffchaffs living near
airports also respond more aggressively to song playback. 5. Since the
decrease in song frequency results in increased overlap with aircraft
noise, these findings cannot be explained as an adaptation to improve
communication. The increased levels of aggression suggests that
chiffchaffs, like humans, might be affected behaviourally by extreme noise
pollution. These findings should influence environmental impact
assessments for airport expansions globally.