Nottebohm F, Nottebohm M E, Crane L A, Wingfield J C
Behav Neural Biol. 1987 Mar;47(2):197-211. doi: 10.1016/s0163-1047(87)90327-x.
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.
在一年的时间里，每月从6只成年雄性金丝雀身上采集歌声样本以及三种性腺激素（睾酮、双氢睾酮和雌二醇）的血液水平样本，这些金丝雀的年龄从12个月到24个月不等。歌声的可变性和新音节类型的增加在夏季和初秋最为显著，9月达到峰值。新音节习得的第二个峰值出现在3月。7月至8月以及2月期间，血液中的睾酮水平特别低。因此，在新音节习得的两个明显峰值之前约1个月，血液中的睾酮水平会下降。另外两种激素的血液水平与歌声学习峰值的相关性不太明显。据推测，激素、神经和行为变化的同时发生有助于成年期的歌声学习。
