ABS 2022
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Female song rates do not correspond with testosterone concentrations in a temperate breeding songbird
Karan J. Odom1, Nora H. Prior1,2, Gregory F. Ball1, Cara A. Krieg3. 1University of Maryland, College Park, MD, United States; 2Cornell University, Ithaca, NY, United States; 3University of Scranton, Scranton, PA, United States

Much research has investigated the neuroendocrine mechanisms regulating male song in temperate songbirds. The classic paradigm is that male song rates increase with circulating testosterone concentrations in the blood early in the breeding season. Very little is known about female birdsong regulation and if song rates increase with circulating testosterone. Female northern house wrens (Troglodytes aedon) have a pronounced peak in singing during female fertile periods at the start of egg laying. We investigated whether this peak in female song corresponds to seasonal changes in circulating testosterone, as seen in male songbirds. Female house wren circulating testosterone was low throughout the breeding season (on average three times lower than breeding male house wren circulating testosterone concentrations) and testosterone levels did not show a significant increase as compared to pre-breeding concentrations at any breeding stage. Therefore, circulating testosterone levels alone do not appear to regulate song rates in adult female house wrens, suggesting that alternative mechanisms besides testosterone concentrations regulate female song rates in this temperate breeding songbird.