Research Group of Ethology, University of Antwerp, Wilrijk, Belgium.
PLoS One. 2012;7(5):e36547. doi: 10.1371/journal.pone.0036547. Epub 2012 May 9.
Numerous studies have focused on song in songbirds as a signal involved in mate choice and intrasexual competition. It is expected that song traits such as song rate reflect individual quality by being dependent on energetic state or condition. While seasonal variation in bird song (i.e., breeding versus non-breeding song) and its neural substrate have received a fair amount of attention, the function and information content of song outside the breeding season is generally much less understood. Furthermore, typically only measures of condition involving body mass are examined with respect to song rate. Studies investigating a potential relationship between song rate and other indicators of condition, such as physiological measures of nutritional condition, are scant. In this study, we examined whether non-breeding song rate in male European starlings (Sturnus vulgaris) reflects plasma metabolite levels (high-density lipoproteins (HDL), albumin, triglycerides and cholesterol) and/or body mass. Song rate was significantly positively related to a principal component representing primarily HDL, albumin and cholesterol (and to a lesser degree plasma triglyceride levels). There was only a trend toward a significant positive correlation between song rate and body mass, and no significant correlation between body mass and the abovementioned principal component. Therefore, our results indicate that nutritional condition and body mass represent different aspects of condition, and that song rate reflects nutritional rather than body condition. Additionally, we also found that intra-individual song rate consistency (though not song rate itself) was significantly positively related to lutein levels, but not to body mass or nutritional condition. Together our results suggest that the relation between physiological measures of nutritional condition and song rate, as well as other signals, may present an interesting line of future research, both inside and outside the breeding season.
许多研究都集中在鸣禽的歌声上，因为歌声是涉及配偶选择和同性竞争的信号。人们期望歌声特征（如歌声频率）能够反映个体的质量，因为这些特征依赖于能量状态或状况。虽然鸟类的季节性歌声变化（即繁殖期和非繁殖期的歌声）及其神经基础已经受到了相当多的关注，但非繁殖期歌声的功能和信息含量通常理解得较少。此外，通常只考虑与体重有关的身体状况的衡量标准来衡量歌声频率。很少有研究调查歌声频率与其他身体状况指标（如营养状况的生理衡量标准）之间的潜在关系。在这项研究中，我们研究了雄性欧洲椋鸟（Sturnus vulgaris）的非繁殖期歌声频率是否反映了血浆代谢物水平（高密度脂蛋白（HDL）、白蛋白、甘油三酯和胆固醇）和/或体重。歌声频率与主要由 HDL、白蛋白和胆固醇组成的主成分呈显著正相关（血浆甘油三酯水平也有一定程度的正相关）。歌声频率与体重之间只有一个显著的正相关趋势，而体重与上述主成分之间没有显著的相关性。因此，我们的研究结果表明，营养状况和体重代表了身体状况的不同方面，而歌声频率反映了营养状况而不是身体状况。此外，我们还发现个体内歌声频率一致性（尽管不是歌声频率本身）与叶黄素水平呈显著正相关，但与体重或营养状况无关。总之，我们的研究结果表明，生理营养状况和歌声频率之间的关系，以及其他信号，可能是未来在繁殖期内外进行有趣研究的一个方向。
