title: Seasonal changes in gonadal hormone levels of adult male canaries and their relation to song.
abstract: Samples of song and blood levels of three gonadal hormones, T, DHT, and E2, were taken at monthly intervals from six adult male canaries over a period of 1 year, as these birds went from 12 to 24 months of age. Song variability and addition of new syllable types were maximal during the summer and early fall, with a peak in September. A secondary peak in new syllable acquisition occurred in March. Blood T levels were particularly low during July-August and during February. Thus, a lowering of blood T levels preceded by about 1 month the two marked peaks in new syllable acquisition. Blood levels of the two other hormones were related less obviously to song learning peaks. It is hypothesized that a concurrence of hormonal, neural, and behavioral changes facilitates song learning in adulthood.
mesh_terms: D000818:Animals; D002171:Canaries / Q000097:blood / Q000502:physiology*; D013196:Dihydrotestosterone / Q000097:blood*; D004958:Estradiol / Q000097:blood*; D007858:Learning / Q000502:physiology; D008297:Male; D010507:Periodicity; D012621:Seasons; D013739:Testosterone / Q000097:blood*; D014828:Vocalization, Animal / Q000502:physiology*
chemical_list: D013196:Dihydrotestosterone; D013739:Testosterone; D004958:Estradiol