Data from: Predicting the effect of urban noise on the active space of avian vocal signals

Urbanization changes the physical environment of non-human species, but
also markedly changes their acoustic environment. Urban noise interferes
with acoustic communication in a range of animals including birds, with
potentially profound impacts on fitness. However, a mechanistic theory to
predict which species of birds will be most affected by urban noise is
lacking. We develop a mathematical model to predict the decrease in the
active space of avian vocal signals when moving from quiet forest habitats
to noisy urban habitats, and find that the magnitude of the decrease is
largely a function of signal frequency. However, this relationship is not
monotonic. A meta-regression of observed increases in the frequency of
birdsong in urban noise supports the model's predictions for signals
with frequencies between 1.5 and 4 kHz. Using the results of the
meta-regression and the model described above, we show that the expected
gain in active space following observed frequency shifts is up to 12%, and
greatest for birds with signals at the lower end of this frequency range.
Our generally-applicable model, along with three predictions regarding the
behavioral and population-level responses of birds to urban noise,
represents an important step towards a theory of acoustic communication in
urban habitats.