Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA.
Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA.
Curr Biol. 2018 Apr 23;28(8):1257-1264.e6. doi: 10.1016/j.cub.2018.03.021. Epub 2018 Apr 12.
Male hummingbirds court females with a high-speed dive in which they "sing" with their tail feathers. The male's choice of trajectory provides him strategic control over acoustic frequency and pressure levels heard by the female. Unlike related species, male Costa's hummingbirds (Calypte costae) choose to place their dives to the side of females. Here we show that this minimizes an audible Doppler curve in their dive sound, thereby depriving females of an acoustic indicator that would otherwise reveal male dive speed. Wind-tunnel experiments indicate that the sounds produced by their feathers are directional; thus, males should aim their tail toward females. High-speed video of dives reveal that males twist half of their tail vertically during the dive, which acoustic-camera video shows effectively aims this sound sideways, toward the female. Our results demonstrate that male animals can strategically modulate female perception of dynamic aspects of athletic motor displays, such as their speed.
雄蜂鸟用高速俯冲向雌鸟求爱，在俯冲过程中雄鸟用尾羽“唱歌”。雄鸟选择的飞行轨迹使他能够对雌性听到的频率和压力水平进行战略性控制。与相关物种不同，雄性 Costa 蜂鸟（Calypte costae）选择将俯冲方向置于雌鸟的侧面。在这里，我们表明，这最大限度地减少了俯冲声音中的可听见的多普勒曲线，从而剥夺了雌性本来可以揭示雄性俯冲速度的声学指示。风洞实验表明，它们羽毛产生的声音是定向的；因此，雄鸟应该将尾巴指向雌性。俯冲的高速视频显示，雄鸟在俯冲过程中将其尾巴的一半垂直扭转，而声像视频显示，这有效地将声音侧向指向雌性。我们的研究结果表明，雄性动物可以战略性地调节雌性对运动表现动态方面的感知，例如速度。
