Data from: Acoustic adaptation to city noise through vocal learning by a songbird

Anthropogenic noise imposes novel selection pressures, especially on
species that communicate acoustically. Many animals – including insects,
frogs, whales, and birds – produce sounds at higher frequencies in areas
with low-frequency noise pollution. Although there is support for animals
changing their vocalizations in real time in response to noise (i.e.,
immediate flexibility), other evolutionary mechanisms for animals that
learn their vocalizations remain largely unexplored. We hypothesize that
cultural selection for signal structures less masked by noise is a
mechanism of acoustic adaptation to anthropogenic noise. We test this
hypothesis by presenting nestling white-crowned sparrows (Zonotrichia
leucophyrs) less-masked (higher frequency) and more masked (lower
frequency) tutor songs either during playback of anthropogenic noise
(noise-tutored treatment) or at a different time from noise playback
(control treatment). As predicted, we find that noise-tutored males learn
less-masked songs significantly more often, whereas control males show no
copying preference, providing strong experimental support for cultural
selection in response to anthropogenic noise. Further, noise-tutored males
reproduce songs at higher frequencies than their tutor, indicating a
distinct mechanism to increase signal transmission in a noisy environment.
Notably, noise-tutored males achieve lower performance songs than their
tutors, suggesting potential costs in a sexual selection framework.