Electronic Thesis and Dissertation Repository


Master of Science




Dr. Elizabeth MacDougall-Shackleton


Vocal performance in birds, measured as the ability to rapidly produce broadband trills, has been proposed to reflect male quality. However, little is known about whether performance is consistent across a male’s song repertoire, or whether better performers also have larger repertoires. I quantified vocal performance in 21 male song sparrows (Melospiza melodia). Performance varied among and within males, but was significantly repeatable when considering multiple exemplars of the same trill type within an individual’s repertoire. This suggests that within-individual variation in performance reflects trill types varying in complexity and performance difficulty. Performance was positively and significantly correlated to song repertoire size, but not with male age, bill or body size. While repeatability of performance between multiple exemplars of the same trill suggests vocal performance could potentially be a reliable signal in birds with multi-song repertoires, performance appears to overlap with song repertoire size in the information conveyed.