Vocalizations match auditory processing in the American tree sparrow (Spizella arborea), dark-eyed junco (Junco hyelmalis), and house finch (Carpodacous mexicanus)
Abstract
We compared the auditory processing and vocalizations of the American tree sparrow (Spizella arborea), dark-eyed junco ( Junco hyelmalis), and house finch (Carpodacus mexicanus) to determine the degree to which vocal signals and auditory systems match in these species. We used the auditory brainstem response (ABR) and the frequency following response (FFR) to determine the ABR auditory thresholds (the lowest stimulus intensities needed to hear a stimuli at given frequencies), the ABR latency (the time it takes a bird to neurologically respond to an acoustic stimulus), ABR amplitude (the number of neuronal units responding to a stimulus), and frequency following response (or FFR: phase locking of neurons in the brainstem to the frequency of an acoustic stimulus). Dark-eyed juncos, which had the highest frequency song, had the lowest ABR thresholds at higher frequencies, whereas the house finch, which had the lowest frequency song, had the lowest ABR thresholds at the lower frequencies. Peak frequency of the vocalization was slightly higher than peak auditory sensitivity in all three species as has been observed in other auditory-vocalization matching studies. ABR amplitude was the greatest and ABR latency shortest at frequencies where vocalizations were most concentrated. Dark-eyed juncos and house finches, which had songs with relatively more frequency modulations, had greater FFR amplitudes than the American tree sparrow, which had songs with less frequency modulation. This study provides further evidence for the matching of vocalizations and auditory systems in birds as well as provides the first ABR thresholds for the American tree sparrow, dark-eyed junco, and house finch and the second study to investigate the frequency following response in birds.
Degree
M.S.
Advisors
Lucas, Purdue University.
Subject Area
Ecology|Behavioral psychology|Behavioral Sciences
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