It is known that disturbance by anthropogenic noise
can influence populations of breeding birds. Many
studies show evidence for a decline in both number of
species and number of individuals due to increased
environmental noise levels caused by road traffic (e.g.
Reijnen, Foppen & Veenbaas 1997; Weiserbs & Jacob
2001; Forman, Reineking & Hersperger 2002). However,
not all species are affected to the same degree, and
some species even appear not to be vulnerable to disturbance
from traffic noise (Fernández-Juricic 2001;
Rheindt 2003). Furthermore, some birds may habituate
quickly to environmental noise exposure (Harms,
Fleming & Stoskopf 1997), but also less sensitive species
that populate noisy habitats can be affected by
background sounds, as the findings of this study suggest.
Even when there are no obvious influences,
environmental noise can have an impact on birds, for
species that do not show an effect on density can still be
affected by acoustical masking of songs.