Age-related changes in the Bengalese finch song motor program.

It is well established that there are remarkable similarities between song learning in oscine birds and acquisition of speech in young children. Human speech shows marked changes with senescence, but few studies have evaluated how song changes with advanced age in songbirds. To investigate the effect of old age on song, we compared song of old Bengalese finches (Lonchura striata domestica) with that of middle-aged birds. The main observed difference was a decrease in the song tempo, largely due to an increased intersyllable duration. Aging also affected the acoustic characteristics of the song, causing a decrease in pitch and in the range of frequency modulations. Gross morphological measurements of selected vocal muscles did not show detectable changes over this age range, suggesting that song deterioration may be due to neural deterioration. The age-induced temporal and acoustic changes in song parallel the acoustic changes that occur in human speech, suggesting songbirds as a suitable model for aging studies on learned vocal behavior.