Females may exert selective pressure on temperate, territorial male songbirds by responding differentially to several categories of song features, including: song output, local song structure, song complexity, and vocal performance. Numerous studies have now shown female preferences for high performance song, including for songs that exhibit increased stereotypy. For species that produce songs with repeated notes having similar structure, older individuals may produce songs with a higher level of stereotypy when compared with younger individuals. In most such cases, singing involves extensive movements of the upper vocal tract, especially the bill. We investigated whether older male grasshopper sparrows (Ammodramus savannarum) produce more stereotyped songs. Territorial song in this species consists of a series of introductory notes followed by a rapidly produced trill, during which the bill is held open and does not track individual notes. We took two approaches to determine whether songs of a cohort of birds were more stereotyped at older ages: an evaluation of variation in several acoustic measurements of the song, and a cross-correlation metric that provided an index of similarity within and across songs. We found that as males aged, they sang more consistent (less variable) songs, despite a lack of associated bill movements during singing. We also found that song similarity was enhanced during comparisons that adjusted for absolute differences in frequency structure. This result suggests that absolute frequencies may remain somewhat more variable as birds age than relative frequency relationships within song.