Garde Baptiste, Wilson Rory P, Lempidakis Emmanouil, Börger Luca, Portugal Steven J, Hedenström Anders, Dell'Omo Giacomo, Quetting Michael, Wikelski Martin, Shepard Emily L C
Biosciences, College of Science, Swansea University, Singleton Park, Swansea, UK.
Department of Biological Sciences, Royal Holloway University of London, Egham, UK.
R Soc Open Sci. 2021 May 19;8(5):210130. doi: 10.1098/rsos.210130.
The power curve provides a basis for predicting adjustments that animals make in flight speed, for example in relation to wind, distance, habitat foraging quality and objective. However, relatively few studies have examined how animals respond to the landscape below them, which could affect speed and power allocation through modifications in climb rate and perceived predation risk. We equipped homing pigeons () with high-frequency loggers to examine how flight speed, and hence effort, varies in relation to topography and land cover. Pigeons showed mixed evidence for an energy-saving strategy, as they minimized climb rates by starting their ascent ahead of hills, but selected rapid speeds in their ascents. Birds did not modify their speed substantially in relation to land cover, but used higher speeds during descending flight, highlighting the importance of considering the rate of change in altitude before estimating power use from speed. Finally, we document an unexpected variability in speed and altitude over fine scales; a source of substantial energetic inefficiency. We suggest this may be a form of protean behaviour adopted to reduce predation risk when flocking is not an option, and that such a strategy could be widespread.
功率曲线为预测动物在飞行速度上的调整提供了依据，例如与风、距离、栖息地觅食质量和目标相关的调整。然而，相对较少的研究考察了动物如何应对其下方的景观，而这可能通过改变爬升率和感知到的捕食风险来影响速度和功率分配。我们给归巢鸽（）配备了高频记录仪，以研究飞行速度以及由此产生的努力程度如何随地形和土地覆盖而变化。鸽子表现出节能策略的混合证据，因为它们通过在山丘前开始上升来最小化爬升率，但在上升过程中选择了较快的速度。鸟类在与土地覆盖相关方面并没有大幅改变其速度，但在下降飞行时使用了更高的速度，这突出了在从速度估计功率使用之前考虑海拔变化率的重要性。最后，我们记录了在精细尺度上速度和海拔的意外变化；这是能量效率低下的一个重要来源。我们认为，这可能是在无法选择成群飞行时为降低捕食风险而采取的一种多变行为形式，并且这种策略可能很普遍。
