Birdsong is a complex learned vocal behavior that relies on auditory experience for development.However,it appears that among different species of close-ended songbirds,there are some variations in the necessity of auditory feedback for maintaining stereotyped adult song.In zebra finches,the deterioration of adult songs following deafness depends on the birds' age.It is unknown whether this age effect is a general rule in other avian species as well.Therefore,we chose Bengalese finches,whose songs show more complexity and have much heavier dependency on auditory feedback than that of zebra finches,to compare the degree of song degradation after hearing loss in old(over 18 months old)and young adult birds(5-6 months old).We found that both syllable sequence and syllable phonology were much less severely affected by deafening in old adults than that in young ones.Moreover,young adults almost lost their capability to sing trills over 6 months following deafening,while old birds continued to sing plenty of trills and trilled syllables after the same period of deafening.Our results suggest that age plays an important role in affecting the dependency of adult song maintenance on auditory feedback in Bengalese finches.Furthermore,the age dependency may be a general phenomenon in different species of close-ended songbirds.
