In some socially monogamous birds, territories sometimes occur in aggregations. The “hidden lek” hypothesis suggests that territorial aggregations might be explained by males establishing territories near successful males (“hotshot” model) or by females preferring to mate in large clusters (“female preference” model). In both scenarios, clusters would provide more opportunities for finding mates and achieving extrapair copulations. Our study tests predictions of these two models in the blue-black grassquit (Volatinia jacarina). Males of this species migrate to their breeding grounds, establish territories within clusters, and initiate courtship displays. These displays consist of vertical leaps synchronized with vocalizations, or only the latter without leaps. The “hotshot” model predicts that: 1) earlier-arriving males would establish territories more centrally within clusters; 2) earlier or centrally positioned males would produce more elaborate displays; and 3) these same males would achieve higher success via within and extrapair fertilizations. The “female preference” model predicts that: 4) pairing success and 5) per-capita extrapair fertilizations would increase with cluster size. We found that earlier-arriving males executed higher leaps and longer songs, but there was no relationship between these traits and male position within clusters. We also found that earlier-arriving males were more likely to obtain extrapair fertilizations. However, we found little evidence that cluster size related to overall or per-capita breeding success. Considered together, our data provide partial validation of the hotshot model of hidden leks and expand on prior findings in this species by showing that females benefit by choosing males leaping higher and settling earlier in clusters.

中文翻译：

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迁徙鸣鸟中隐藏的韭菜：较早和更具吸引力的雄性的交配优势

在一些社会一夫一妻制的鸟类中，有时会聚集在一起。“隐性韭菜”假说表明，领土聚集可能由雄性在成功成年雄性附近建立领土（“热点”模式）或雌性倾向于在大群中交配（“雌性偏好”模式）来解释。在这两种情况下，集群都将提供更多机会寻找伴侣并实现对配对。我们的研究在蓝黑色草场（Volatinia jacarina）中测试了这两种模型的预测）。该物种的雄性迁移到其繁殖地，在集群内建立领土，并发起求爱展示。这些显示包括与发声同步的垂直飞跃，或者只有无飞跃的后者。“热门”模型预测：1）较早到达的雄性将在集群内更集中地建立领土；2）较早或居中的雄性会产生更精细的显示；3）这些相同的雄性将通过内部和外部配对受精获得更高的成功率。“女性偏爱”模型预测：4）配对成功和5）人均超配对受精量将随着簇的大小而增加。我们发现，到达较早的雄性跳动更高，歌曲更长，但这些特征与簇中雄性位置之间没有关系。我们还发现，较早到达的雄性更有可能获得成对受精。但是，我们发现几乎没有证据表明簇的大小与总体或人均育种成功有关。综合考虑，我们的数据提供了对部分隐性韭菜热模型的部分验证，并通过显示雌性受益于选择雄性跃升较高且较早定居的雄性种群，从而对该物种的先前发现进行了扩展。