Endocrine mechanism regulating female song in a natural singing temperate songbird
Poster Number
61
Faculty Mentor Name
Karan Odom
Format
Poster Presentation
Research or Creativity Area
Business
Abstract
Animals exhibit a wide array of elaborate traits, from flashy colors to complex acrobatic courtship displays (Andersson and Iwasa 1996). These traits have traditionally been viewed as outcomes of sexual selection to help males attract and compete for females (Emlen and Oring 1977). However, females of many animals also have elaborate traits (Kraaijeveld 2007). Song is one such elaborate behavior in songbirds (Odom 2014). While male birdsong mechanisms are well studied, endocrine regulation of female birdsong remains poorly understood. (Rose et al. 2022). Testosterone (T) is a principal endocrine regulator of male birdsong learning and production (Marler 1988; Alward 2018). Female songbirds contradict what is known in males: (1) many female temperate songbirds only sing for brief periods during early breeding season (Krieg and Getty 2016) and (2) Female song can occur at lower plasma T concentrations than in males (Odom et al, in press). In males, T is converted to estradiol (E2) locally in the brain via aromatization, activating song production (Ball 2003; Remage-Healey 2009). T can also be converted to dihydrotestosterone (DHT), a non-aromatizable androgen that activates androgen receptors. E2 rapidly enlarges the key song-control nucleus (HVC) in the male songbird brain, while aromatase inhibition causes this nucleus to shrink and suppresses singing behavior. E2 treatment reverses this effect (Soma 2004). Therefore, E2 might regulate natural female song in wild populations. House wrens (Troglodytes aedon) are a widespread, nest-box–breeding songbird with sex-specific songs (Krieg and Getty 2016). This study will be the first to experimentally test the role of E2 and androgen receptor signaling in regulating natural female song in a wild breeding population. By elevating hormone levels and using playback experiments, this study will clarify sex-specific endocrine mechanisms underlying vocal behavior.
Purpose
● Does inhibiting aromatization using fadrozole suppress natural female song?
● Does testosterone (T), estradiol (E2), and/or dihydrotestosterone (DHT) induce female singing during incubation period, when females naturally stop singing?
● Can fadrozole suppress singing after implantation?
Results
In the process of data collection.
Significance
This study will be one of the first to examine how steroid hormones, particularly estradiol, regulate song in female songbirds in wild populations. By directly elevating hormone concentrations and pairing these treatments with territorial playback experiments, we will be able to test whether estradiol is the primary driver of female song during the breeding season. The findings of this study will clarify how similar elaborate traits can be shaped by distinct hormonal pathways in males and females, advancing our understanding of sex-specific endocrine mechanisms. This work will contribute to the growing recognition that female song is both widespread and functionally important. The study will also begin to explain how endocrine processes shape the evolution and expression of elaborate behavioral traits in females.
Location
University of the Pacific, DeRosa University Center
Start Date
24-4-2026 11:00 AM
End Date
24-4-2026 2:00 PM
Endocrine mechanism regulating female song in a natural singing temperate songbird
University of the Pacific, DeRosa University Center
Animals exhibit a wide array of elaborate traits, from flashy colors to complex acrobatic courtship displays (Andersson and Iwasa 1996). These traits have traditionally been viewed as outcomes of sexual selection to help males attract and compete for females (Emlen and Oring 1977). However, females of many animals also have elaborate traits (Kraaijeveld 2007). Song is one such elaborate behavior in songbirds (Odom 2014). While male birdsong mechanisms are well studied, endocrine regulation of female birdsong remains poorly understood. (Rose et al. 2022). Testosterone (T) is a principal endocrine regulator of male birdsong learning and production (Marler 1988; Alward 2018). Female songbirds contradict what is known in males: (1) many female temperate songbirds only sing for brief periods during early breeding season (Krieg and Getty 2016) and (2) Female song can occur at lower plasma T concentrations than in males (Odom et al, in press). In males, T is converted to estradiol (E2) locally in the brain via aromatization, activating song production (Ball 2003; Remage-Healey 2009). T can also be converted to dihydrotestosterone (DHT), a non-aromatizable androgen that activates androgen receptors. E2 rapidly enlarges the key song-control nucleus (HVC) in the male songbird brain, while aromatase inhibition causes this nucleus to shrink and suppresses singing behavior. E2 treatment reverses this effect (Soma 2004). Therefore, E2 might regulate natural female song in wild populations. House wrens (Troglodytes aedon) are a widespread, nest-box–breeding songbird with sex-specific songs (Krieg and Getty 2016). This study will be the first to experimentally test the role of E2 and androgen receptor signaling in regulating natural female song in a wild breeding population. By elevating hormone levels and using playback experiments, this study will clarify sex-specific endocrine mechanisms underlying vocal behavior.
