Meeting Abstract
P2.9 Monday, Jan. 5 Context-dependent modulation of song effort in a territorial songbird, the Lincoln’s sparrow SEWALL, K. B.**; SOCKMAN, K. W.; University of North Carolina, Chapel Hill; University of North Carolina, Chapel Hill ksewall@email.unc.edu
Male songbirds often establish territories and attract mates by singing. Males may assess their immediate competitors based on the relative quality of their song. In many songbirds high quality songs are longer, more complex and contain versions of particular song components, referred to as trills, that are more difficult to produce. Males should be expected to modulate their song effort to compete within the scope of their current song environment, down and up-regulating the quality or quantity of the song they produce as a function of their competitors songs. Modulation of song output could be achieved through environmentally-influenced changes in singing motivation, which may be regulated by argenine vasotosin (AVT) secretion in some midbrain or forebrain regions. Additionally, modulation of song output could be achieved through environmentally-influenced changes in song output, which are associated with the volumes of vocal-control nuclei in the forebrain. To test these predictions about the mechanisms involved in the context-dependent modulation of song effort, we manipulated the song environment of territorial male songbirds, Lincoln’s sparrows (Melospiza lincolnii) by exposing them to recordings of either high or low quality songs for one week. We found that the daily song count increased over the course of the study for males in both treatments, but the males in the high quality song environment produced more songs overall than males in the low quality song environment. We conclude that male Lincoln’s sparrows are sensitive to variation in the quality of songs prevalent in their surroundings and that they modulate their own mate attraction effort as a function of their social environment. These behavioral responses may be mediated by environmentally-influenced changes in AVT or the volumes of some song-control nuclei.
