Behaviour 2019
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Performance constraints and effects of steroid hormones on trilled vocalizations in canaries (Serinus canaria)
Ednei B. dos Santos1, David M. Logue2, Gregory F. Ball3, Charlotte A. Cornil1, Jacques Balthazart1. 1GIGA Neurosciences, University of Liege, Liege, Liege, Belgium; 2Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada; 3Department of Psychology, University of Maryland, College Park, Maryland, United States

Physiologically challenging sexual displays have the potential to convey information about an individual’s vigor, skill, and motivation. In canaries, females prefer songs with trills that include ‘sexy-syllables’, which are wide band two-note syllables produced at a fast rate (≥ 17 elements s-1). Producing such trills requires high motor coordination and respiratory capacity, and may reveal trade-offs indicative of limits to the speed of both frequency modulation and respiration. Performance constraints were first analyzed in a sample of 16,423 trills from 30 male canaries. Potential effects of steroid hormones on these constraints were also analyzed in 42,198 trills recorded over a period of 6 weeks from 3 groups of castrated males and 3 groups of photoregressed females that received Silastic implants filled with testosterone (T) or T plus estradiol (E2) or left empty as control. In both datasets, we identified trade-offs at the note and song level, which are consistent with the hypothesis that limits on frequency modulation and respiration constrain song production. We are now quantifying possible sex differences and differential effects of T vs. E2 on these trade-offs.