Data from: Vigor and skill in the acrobatic mating displays of a Neotropical songbird

Animal social behaviors are often mediated by signals that provide information about signaler attributes. Although some signals are structurally simple, others are temporally dynamic and multifaceted. In such cases, exaggeration of some display components is likely to curtail the expression of others. We quantified features of the acrobatic, multimodal “leap display” of blue-black grassquits (Volatinia jacarina), which appears to entail moderate-to-high performance levels in terms of vigor and skill. We video recorded and quantified leap parameters (height, duration, rotation angle, launch velocity, and number of wing beats) and assessed how these parameters covaried with each other and with vocal parameters, display rates, and body mass index. Our analyses revealed correlations among multiple performance variables: leap height, duration, launch velocity, and number of wing beats. Leap height also correlated positively with song duration. By contrast, no leap parameters covaried with rotation angle. Our analyses also revealed a trade-off in vigor and skill-based leap attributes: birds with a lower body mass index showed a negative relationship between leap heights and the proportion of displays that included leaps (vs. perched vocalizations only). Our results identify directions of display evolution subject to mechanical or timing constraints and provide evidence that display attributes that emphasize vigor and skill may limit one another. Our results also support a key expectation of handicap models of display evolution, which is that costs of display execution should be borne disproportionately by signalers of lower quality.动物的社会行为通常由传递信号发出者个体属性信息的信号所介导。尽管部分信号结构较为简单，其余信号则具备时序动态性且多维度复杂。在此类情境下，对部分展示组分的过度强化，往往会抑制其他组分的表达。我们对蓝黑草鹀（Volatinia jacarina）兼具多模态特征的杂技式跳跃展示的各项特征进行了量化，该展示行为在活力与技巧层面均达到了中高水平的表现水准。我们通过录像记录并量化了跳跃行为的多项参数（高度、时长、旋转角度、起跳速度与振翅次数），并探究了这些参数彼此间的相关性，以及它们与发声参数、展示频次和身体质量指数的关联。分析结果显示，多项表现变量间存在显著相关：跳跃高度、时长、起跳速度与振翅次数两两相关。此外，跳跃高度与鸣唱时长呈显著正相关。相较而言，所有跳跃参数均未与旋转角度存在相关性。本研究的分析还揭示了基于活力与技巧的跳跃特征间存在权衡：身体质量指数较低的个体，其跳跃高度与包含跳跃行为的展示占比（相较于仅停栖时的鸣唱）呈负相关。本研究明确了受机械约束与时序限制的展示行为演化方向，并为强调活力与技巧的展示特征彼此间存在制约提供了实证依据。本研究结果同时支持了展示演化障碍模型的核心预期：即展示行为实施的成本，应由质量较低的信号发出者不成比例地承担。