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 (Columba livia) 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对飞行速度的调整提供了基础，例如与风、距离、栖息地觅食质量和目标相关的调整。然而，相对较少的研究探讨了动物如何对其下方的景观做出反应，这可能通过改变攀爬率和感知的捕食风险来影响速度和力量分配。我们为信鸽（ Columba livia ）配备了高频记录仪，以检查飞行速度以及由此产生的努力如何随地形和土地覆盖而变化。鸽子在节能策略方面表现出好坏参半的证据，因为它们通过在山前开始上升来最大限度地降低爬升率，但在上升时选择快速速度。鸟类并没有因土地覆盖而大幅改变其速度，而是在下降飞行时使用更高的速度，这凸显了在根据速度估计功率使用之前考虑高度变化率的重要性。最后，我们记录了在精细尺度上速度和高度的意外变化；能源效率严重低下的一个根源。我们认为，这可能是一种多变的行为形式，用于在无法选择蜂群时降低捕食风险，并且这种策略可能会广泛传播。