Field Research Station at Fort Missoula, Division of Biological Sciences, University of Montana, Missoula, MT, United States of America.
School of Biological Sciences, Bangor University, Bangor, Gwynedd, United Kingdom.
PLoS One. 2018 Jul 25;13(7):e0199662. doi: 10.1371/journal.pone.0199662. eCollection 2018.
The natural world is filled with substrates of varying properties that challenge locomotor abilities. Birds appear to transition smoothly from aerial to terrestrial environments during take-offs and landings using substrates that are incredibly variable. It may be challenging to control movement on and off compliant (flexible) substrates such as twigs, yet birds routinely accomplish such tasks. Previous research suggests that birds do not use their legs to harness elastic recoil from perches. Given avian mastery of take-off and landing, we hypothesized that birds instead modulate wing, body and tail movements to effectively use compliant perches. We measured take-off and landing performance of diamond doves (Geopelia cuneata (N = 5) in the laboratory and perch selection in this species in the field (N = 25). Contrary to our hypothesis, doves do not control take-off and landing on compliant perches as effectively as they do on stiff perches. They do not recover elastic energy from the perch, and take-off velocities are thus negatively impacted. Landing velocities remain unchanged, which suggests they may not anticipate the need to compensate for compliance. Legs and wings function as independent units: legs produce lower initial velocities when taking off from a compliant substrate, which negatively impacts later flight velocities. During landing, significant stability problems arise with compliance that are ameliorated by the wings and tail. Collectively, we suggest that the diamond dove maintains a generalized take-off and landing behavior regardless of perch compliance, leading us to conclude that perch compliance represents a challenge for flying birds. Free-living diamond doves avoid the negative impacts of compliance by preferentially selecting perches of larger diameter, which tend to be stiffer.
自然界充满了各种具有不同特性的基质，这些基质挑战着动物的运动能力。鸟类在起飞和降落时，似乎可以轻松地在极其多变的基质上从空中过渡到陆地环境。在柔软的基质（如树枝）上控制运动可能具有挑战性，但鸟类通常能够完成此类任务。先前的研究表明，鸟类不会利用腿部来利用栖木的弹性回弹。考虑到鸟类在起飞和降落方面的出色表现，我们假设鸟类会调节翅膀、身体和尾巴的运动，以有效地利用柔软的栖木。我们在实验室中测量了钻石鸽（Geopelia cuneata）（N = 5）的起飞和降落性能，并在该物种的野外研究中测量了其栖木选择（N = 25）。与我们的假设相反，鸽子在柔软的栖木上的起飞和降落控制效果不如在坚硬的栖木上。它们不会从栖木中回收弹性能量，因此起飞速度受到负面影响。降落速度保持不变，这表明它们可能没有预料到需要补偿柔软性。腿和翅膀作为独立的单元发挥作用：鸽子从柔软的基质起飞时，腿部产生的初始速度较低，这会对后续的飞行速度产生负面影响。在降落时，柔软性会导致严重的稳定性问题，这些问题可以通过翅膀和尾巴来缓解。总的来说，我们认为钻石鸽保持了一种通用的起飞和降落行为，无论栖木的柔软性如何，这导致我们得出结论，栖木的柔软性对飞行鸟类来说是一个挑战。自由生活的钻石鸽通过优先选择直径较大的栖木来避免柔软性的负面影响，因为这些栖木往往更硬。
