Urban noise can interfere with avian communication through masking, but birds can reduce this interference by altering their vocalizations. Although several experimental studies indicate that birds can rapidly change their vocalizations in response to sudden increases in ambient noise, none have investigated whether this is a learned response that depends on previous exposure. Black-capped chickadees (Poecile atricapillus) change the frequency of their songs in response to both fluctuating traffic noise and experimental noise. We investigated whether these responses to fluctuating noise depend on familiarity with noise. We confirmed that males in noisy areas sang higher-frequency songs than those in quiet areas, but found that only males in already-noisy territories shifted songs upwards in immediate response to experimental noise. Unexpectedly, males in more quiet territories shifted songs downwards in response to experimental noise. These results suggest that chickadees may require prior experience with fluctuating noise to adjust vocalizations in such a way as to minimize masking. Thus, learning to cope may be an important part of adjusting to acoustic life in the city.

Average frequency use and local ambient noiseAverage frequency measures of singing black-capped chickadees. Measures are provided as average Hz and as averages made from songs which were first log10 transformed ('from log'). Habitat urbanization index and spl (dB(Z)) measures for each male's territory are also provided.dryad_data_pre.csvResponse to experimental noiseAverage changes in frequency measure made by black-capped chickadees in response to experimental noise. Mean change is calculated for songs in Hz and for songs which were first log10 transformed ('from log'). Habitat urbanization index and spl (dB(Z)) measures for each male's territory are also provided.dryad_data_exp.csv