Anthropophony and birds Soundscape ecology

anthropophony, sound generated human activities, plays important role in contemporary soundscapes

birds have been used study organisms in of research concerning wildlife responses anthropogenic noise, , resulting literature documents many effects relevant other taxa affected anthropophony. birds may particularly sensitive noise pollution given rely heavily on acoustic signals intraspecific communication. indeed, wide range of studies demonstrate birds use altered songs in noisy environments. research on great tits in urban environment revealed male birds inhabiting noisy territories tended use higher frequency sounds in songs. presumably these higher-pitched songs allow male birds heard above anthropogenic noise, tends have high energy in lower frequency range thereby masking sounds in spectra. follow-up study of multiple populations confirmed great tits in urban areas sing increased minimum frequency relative forest-dwelling birds. in addition, study suggests noisy urban habitats host birds use shorter songs repeat them more rapidly. in contrast frequency modulations, birds may increase amplitude (loudness) of songs decrease masking in environments elevated noise. experimental work , field observations show these song alterations may result of behavioral plasticity rather evolutionary adaptations noise (i.e., birds actively change song repertoire depending on acoustic conditions experience). in fact, avian vocal adjustments anthropogenic noise unlikely products of evolutionary change because high noise levels relatively recent selection pressure. however, not bird species adjust songs improve communication in noisy environments, may limit ability occupy habitats subject anthropogenic noise. in species, individual birds establish relatively rigid vocal repertoire when young, , these sorts of developmental constraints may limit ability make vocal adjustments later in life. thus, species not or cannot modify songs may particularly sensitive habitat degradation result of noise pollution.

effects of anthropophony on auditory communication studied in great tit

even among birds able alter songs better heard in environments inundated anthropophony, these behavioral changes may have important fitness consequences. in great tit, example, there tradeoff between signal strength , signal detection depends on song frequency. male birds include more low frequency sounds in song repertoire experience better sexual fidelity mates results in increased reproductive success. however, low frequency sounds tend masked when anthropogenic noise present, , high frequency songs more effective @ eliciting female responses under these conditions. birds may therefore experience competing selective pressures in habitats high levels of anthropogenic noise: pressure call more @ lower frequencies in order improve signal strength , secure mates versus opposing pressure sing @ higher frequencies in order ensure calls detected against background of anthrophony. in addition, use of vocalizations, including high amplitude sounds reduce masking in noisy environments, may impose energetic costs reduce fitness. because of reproductive trade-offs , other stresses impose on birds, noisy habitats may represent ecological traps, habitats in individuals have reduced fitness yet colonized @ rates greater or equal other habitats.

anthropophony may have population- or community-level impacts on avian fauna. 1 study focusing on community composition found habitats exposed anthropophony hosted fewer bird species regions without noise, both areas had similar numbers of nests. in fact, nests in noisy habitats had higher survival laid in control habitats, presumably because noisy environments hosted fewer western scrub jays major nest predators of other birds. thus, anthropophony can have negative effects on local species diversity, species capable of coping noise disturbance may benefit exclusion of negative species interactions in areas. other experiments suggest noise pollution has potential affect avian mating systems altering strength of pair bonds. when exposed high amplitude environmental noise in laboratory setting, zebra finches, monogamous species, show decreased preference mated partners. similarly, male reed buntings in quiet environments more part of mated pair males in noisy locations. such effects may result in reduced reproductive output of birds subject high levels of environmental noise.