Seasonally breeding animals concentrate courtship to a particular time of year such that their offspring will be reared in a favorable environment. In house sparrows, Passer domesticus, primary (gonads) and secondary (song, plumage, beak color, etc) sexual characteristics are expressed differentially depending on the photoperiod. Removal of the pineal gland (PINX) has no effect on seasonal rhythms in gonad size but alters the photostimulated increase in vocal rate and complexity. Administration of long durations of melatonin, indicative of short days of winter, prevents seasonal recrudescence of song control nuclei in photostimulated house sparrows. In this study, male PINX house sparrows were exposed to three durations of melatonin, while vocalization and locomotor behavior were recorded as they were transitioned from short photoperiod to equinoctial photoperiods of spring. Birds receiving short duration melatonin or vehicle control increased dawn and dusk choruses as well as call complexity. Long durations of melatonin prevented this expansion to a spring-like vocal state observed in birds receiving the short duration of melatonin or vehicle control. The daily distribution of locomotor activity, beak color, and testis size was unaffected by treatment. Vocal state change was defined by our measures in two capacities: (i) increased dawn and dusk choruses, and (ii) an increase in calls associated with territory and mate attraction compared to the winter-like "social song." We conclude that house sparrows use the calendar information provided by melatonin duration to control seasonal vocalization behavior, independent of effects on and of the gonads.

中文翻译：

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褪黑素持续时间可以控制鸣禽的光周期声态变化。

季节性繁殖的动物会在一年中的某个特定时间进行求偶，以便在有利的环境中饲养它们的后代。在麻雀中，Passer domesticus，初生（性腺）和次生（歌曲，羽毛，喙颜色等）的性特征取决于光周期而有所不同。去除松果体（PINX）对性腺大小的季节性节律没有影响，但是改变了光刺激的声速和复杂性的增加。长期服用褪黑激素可预示冬季短暂的几天，可防止受光刺激的麻雀的歌曲控制核出现季节性再发。在这项研究中，雄性PINX麻雀接触了三段褪黑素，同时记录了发声和运动行为，因为它们从春季的短光周期过渡到等角光周期。接受短期褪黑激素或车辆控制的鸟类会增加黎明和黄昏的合唱以及呼叫的复杂性。长期服用褪黑激素可防止这种情况扩展到在接受短期褪黑激素或媒介物控制的鸟类中观察到的类似弹簧的发声状态。运动的日常分布，喙的颜色和睾丸的大小不受治疗的影响。通过我们的措施，人声状态变化以两种能力来定义：（i）黎明和黄昏合唱的增加，以及（ii）与冬天类似的“社交歌曲”相比，与领土和伴侣吸引相关的呼唤有所增加。