Behaviour 2019
Maturational Changes in Song Sparrow Song
Katja H. Kochvar1, Susan Peters2, Matthew N. Zipple3, Stephen Nowicki2. 1Memorial University of Newfoundland, St. John's, NL, Canada; 2Duke University, Durham, NC, United States; 3Cornell University, Ithaca, NY, United States

Age-related changes in the production of sexually selected assessment signals have been identified across a diverse range of taxa. One important type of change occurs after a signaler reaches breeding age, a phenomenon known as delayed maturation. Delayed maturation has been observed in the songs of several bird species, with potential fitness consequences for males as a byproduct of female choosiness or male competition. We analyzed songs recorded across the first three years of life in a cohort of hand-reared song sparrows (Melospiza melodia) to detect early-life age-related changes in song. We focused on three measures of song complexity and five measures of song production patterns. Seven of the 8 characteristics changed significantly within individuals as birds aged from 1 to 2 years of age as well as from 1 to 3 years of age, whereas no significant changes occurred from 2 to 3 years of age. Based on these features, a linear discriminant model could distinguish between the song of young (age 1) and older (age 2 and 3) adult males, providing support for song as an indicator of age in this species.