Data_Sheet_2_Rapid Shifts in Visible Carolina Grasshopper (Dissosteira carolina) Coloration During Flights.xlsx

Some brightly colored structures are only visible when organisms are moving, such as parts of wings that are only visible in flight. For example, the primarily brown Carolina grasshopper (Dissosteira carolina) has contrasting black-and-cream hindwings that appear suddenly when it takes off, then oscillate unpredictably throughout the main flight before disappearing rapidly upon landing. However, the temporal dynamics of hindwing coloration in motion have not previously been investigated, particularly for animals that differ from humans in their temporal vision. To examine how quickly this coloration appears to a variety of non-human observers, we took high-speed videos of D. carolina flights in the field. For each of the best-quality takeoffs and landings, we performed a frame-by-frame analysis on how the relative sizes of the different-colored body parts changed over time. We found that in the first 7.6 ± 1.5 ms of takeoff, the hindwings unfurled to encompass 50% of the visible grasshopper, causing it to roughly double in size. During the main flight, the hindwings transitioned 6.4 ± 0.4 times per second between pauses and periods of active wing-beating (31.4 ± 0.5 Hz), creating an unstable, confusing image. Finally, during landings, the hindwings disappeared in 11.3 ± 3.0 ms, shrinking the grasshopper to 69 ± 9% of its main flight size. Notably, these takeoffs and landings occurred faster than most recorded species are able to sample images, which suggests that they would be near-instantaneous to a variety of different viewers. We therefore suggest that D. carolina uses its hindwings to initially startle predators (deimatic defense) and then confuse them and disrupt their search images (protean defense) before rapidly returning to crypsis.

某些色彩鲜艳的结构仅在生物运动时可见，例如仅能在飞行中显现的翅膀部分。例如，以棕色为主色调的卡罗来纳蝗虫（Dissosteira carolina）拥有对比鲜明的黑白相间的后翅，当其起飞时，这些后翅会突然显现，并在主要飞行阶段中不规则地摆动，直至着陆时迅速消失。然而，关于运动中后翅颜色变化的时序动力学尚未得到深入研究，尤其是对于与人类在时间视觉上存在差异的动物。为了探究这种颜色变化对于各种非人类观察者而言显现的速度，我们对其在野外飞行中的行为进行了高速摄影记录。对于每次拍摄中质量最佳的起飞和着陆瞬间，我们进行了逐帧分析，以观察不同颜色身体部分相对大小的随时间变化。我们发现，在起飞的最初7.6 ± 1.5毫秒内，后翅展开覆盖了可见蝗虫的50%，使蝗虫的体积大致翻倍。在主要飞行阶段，后翅在暂停和主动拍打翅膀的周期之间以6.4 ± 0.4次每秒的频率转换，创造出不稳定且令人困惑的图像。最后，在着陆过程中，后翅在11.3 ± 3.0毫秒内消失，使蝗虫的体积缩小至主要飞行阶段体积的69 ± 9%。值得注意的是，这些起飞和着陆的速度超过了大多数已记录物种能够采样图像的速度，这表明对于各种不同的观察者而言，这些动作几乎是瞬间的。因此，我们推测D. carolina利用其后翅首先用以惊吓捕食者（惊吓防御），然后混淆它们并扰乱它们的搜索图像（变形防御），之后迅速恢复至隐匿状态。