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Abstract：
BACKGROUND: Territorial songbirds vocalise intensively before sunrise and then decrease their vocal activity. This creates a communication network that disseminates essential information for both males and females. The function of dawn chorus in birds has been frequently interpreted according to seasonal variation of singing as the breeding season advances, but potential differences in seasonal variation of song and calls for the same species have not been taken into account.
METHODS: We chose Dupont\'s Lark as a model species to study whether the seasonal pattern of dawn chorus differs between singing and calling activity, because in this species most daily songs and calls are uttered at dawn. We registered vocal activity of Dupont\'s Lark before and around dawn in three different populations, through repeated sampling over the entire breeding season of two consecutive years.
RESULTS: We found that dawn singing parameters remained constant or presented an increasing trend while dawn calling activity decreased as breeding season advanced. We also found different daily patterns for singing and calling, with birds calling mostly during the first 30 minutes of dawn choruses and singing peaking afterwards.
CONCLUSIONS: The different time patterns of songs and calls may indicate that they serve diverse functions at dawn in the Dupont\'s Lark. Relaxation of dawn calling activity after the first month of the breeding season would suggest that dawn calling may be mainly related to mate attraction, while constant dawn singing throughout the breeding period would support a relationship of dawn singing to territorial defence. Our study highlights that the type of vocalisation used is an important factor to consider in further research on dawn choruses, since results may differ depending on whether calls or songs are analysed.
METHODS: We chose Dupont\'s Lark as a model species to study whether the seasonal pattern of dawn chorus differs between singing and calling activity, because in this species most daily songs and calls are uttered at dawn. We registered vocal activity of Dupont\'s Lark before and around dawn in three different populations, through repeated sampling over the entire breeding season of two consecutive years.
RESULTS: We found that dawn singing parameters remained constant or presented an increasing trend while dawn calling activity decreased as breeding season advanced. We also found different daily patterns for singing and calling, with birds calling mostly during the first 30 minutes of dawn choruses and singing peaking afterwards.
CONCLUSIONS: The different time patterns of songs and calls may indicate that they serve diverse functions at dawn in the Dupont\'s Lark. Relaxation of dawn calling activity after the first month of the breeding season would suggest that dawn calling may be mainly related to mate attraction, while constant dawn singing throughout the breeding period would support a relationship of dawn singing to territorial defence. Our study highlights that the type of vocalisation used is an important factor to consider in further research on dawn choruses, since results may differ depending on whether calls or songs are analysed.
摘要：
背景：领土鸣鸟在日出前密集发声，然后减少发声活动。这创建了一个传播男性和女性基本信息的通信网络。随着繁殖季节的到来，经常根据歌唱的季节性变化来解释鸟类中黎明合唱的功能，但是没有考虑到歌曲和呼唤相同物种的季节性变化的潜在差异。
方法：我们选择杜邦的云雀作为模型物种，以研究黎明合唱的季节性模式是否在歌唱和呼唤活动之间有所不同，因为在这个物种中，大多数日常歌曲和电话都是在黎明时发出的。我们在三个不同的种群中记录了Dupont\'sLark在黎明之前和附近的声音活动，通过连续两年在整个繁殖季节重复采样。
结果：我们发现，随着繁殖季节的发展，黎明歌唱参数保持不变或呈增加趋势，而黎明呼唤活动则下降。我们还发现了不同的日常唱歌和打电话模式，鸟儿大多在黎明合唱的前30分钟打电话，然后唱歌达到顶峰。
结论：歌曲和通话的不同时间模式可能表明它们在杜邦的百灵鸟黎明时具有多种功能。繁殖季节的第一个月后，黎明呼唤活动的放松表明，黎明呼唤可能主要与配偶吸引有关，而在整个繁殖期间不断的黎明歌唱将支持黎明歌唱与领土防御的关系。我们的研究强调，使用的发声类型是在进一步研究黎明合唱时需要考虑的重要因素，因为结果可能会有所不同，这取决于是否分析电话或歌曲。
方法：我们选择杜邦的云雀作为模型物种，以研究黎明合唱的季节性模式是否在歌唱和呼唤活动之间有所不同，因为在这个物种中，大多数日常歌曲和电话都是在黎明时发出的。我们在三个不同的种群中记录了Dupont\'sLark在黎明之前和附近的声音活动，通过连续两年在整个繁殖季节重复采样。
结果：我们发现，随着繁殖季节的发展，黎明歌唱参数保持不变或呈增加趋势，而黎明呼唤活动则下降。我们还发现了不同的日常唱歌和打电话模式，鸟儿大多在黎明合唱的前30分钟打电话，然后唱歌达到顶峰。
结论：歌曲和通话的不同时间模式可能表明它们在杜邦的百灵鸟黎明时具有多种功能。繁殖季节的第一个月后，黎明呼唤活动的放松表明，黎明呼唤可能主要与配偶吸引有关，而在整个繁殖期间不断的黎明歌唱将支持黎明歌唱与领土防御的关系。我们的研究强调，使用的发声类型是在进一步研究黎明合唱时需要考虑的重要因素，因为结果可能会有所不同，这取决于是否分析电话或歌曲。
