Data from: Are signals of aggressive intent less honest in urban habitats?

How anthropogenic change affects animal social behavior, including
communication is an important question. Urban noise often drives shifts in
acoustic properties of signals but the consequences of noise for the
honesty of signals – i.e. how well they predict signaler behavior – is
unclear. Here we examine whether honesty of aggressive signaling is
compromised in male urban song sparrows (Melospiza melodia). Song sparrows
have two honest close-range signals: the low amplitude soft songs (an
acoustic signal) and wing waves (a visual signal) but whether the honesty
of these signals is affected by urbanization has not been examined. If
soft songs are less effective in urban noise, we predict that they should
predict attacks less reliably in urban habitats compared to rural
habitats. We confirmed earlier findings that urban birds were more
aggressive than rural birds and found that acoustic noise was higher in
urban habitats. Urban birds still sang more soft songs than rural birds.
High rates of soft songs and low rates of loud songs predicted attacks in
both habitats. Thus, while urbanization has a significant effect on
aggressive behaviors, it might have a limited effect on the overall
honesty of aggressive signals in song sparrows. We also found evidence for
a multimodal shift: urban birds tended to give proportionally more wing
waves than soft songs than rural birds, although whether that shift is due
to noise-dependent plasticity is unclear. These findings encourage further
experimental study of the specific variables that are responsible for
behavioral change due to urbanization.