Dehnhard Nina, Klekociuk Andrew R, Emmerson Louise
Department of Biology Behavioural Ecology and Ecophysiology Group University of Antwerp Antwerp Belgium.
Department of Agriculture, Water and the Environment Australian Antarctic Division Kingston Tas. Australia.
Ecol Evol. 2021 Apr 6;11(9):4972-4991. doi: 10.1002/ece3.7501. eCollection 2021 May.
For procellariiform seabirds, wind and morphology are crucial determinants of flight costs and flight speeds. During chick-rearing, parental seabirds commute frequently to provision their chicks, and their body mass typically changes between outbound and return legs. In Antarctica, the characteristic diurnal katabatic winds, which blow stronger in the mornings, form a natural experimental setup to investigate flight behaviors of commuting seabirds in response to wind conditions. We GPS-tracked three closely related species of sympatrically breeding Antarctic fulmarine petrels, which differ in wing loading and aspect ratio, and investigated their flight behavior in response to wind and changes in body mass. Such information is critical for understanding how species may respond to climate change. All three species reached higher ground speeds (i.e., the speed over ground) under stronger tailwinds, especially on return legs from foraging. Ground speeds decreased under stronger headwinds. Antarctic petrels (; intermediate body mass, highest wing loading, and aspect ratio) responded stronger to changes in wind speed and direction than cape petrels (; lowest body mass, wing loading, and aspect ratio) or southern fulmars (; highest body mass, intermediate wing loading, and aspect ratio). Birds did not adjust their flight direction in relation to wind direction nor the maximum distance from their nests when encountering headwinds on outbound commutes. However, birds appeared to adjust the timing of commutes to benefit from strong katabatic winds as tailwinds on outbound legs and avoid strong katabatic winds as headwinds on return legs. Despite these adaptations to the predictable diurnal wind conditions, birds frequently encountered unfavorably strong headwinds, possibly as a result of weather systems disrupting the katabatics. How the predicted decrease in Antarctic near-coastal wind speeds over the remainder of the century will affect flight costs and breeding success and ultimately population trajectories remains to be seen.
对于鹱形目海鸟而言，风和形态是飞行成本和飞行速度的关键决定因素。在育雏期间，海鸟父母频繁往返为雏鸟提供食物，其体重在外出和返回行程中通常会发生变化。在南极洲，典型的昼夜下坡风在早晨吹得更强，形成了一个天然的实验装置，用于研究往返海鸟在不同风况下的飞行行为。我们利用GPS追踪了三种同域繁殖的南极管鼻藿属海鸟，它们在翼载荷和展弦比上存在差异，并研究了它们对风和体重变化的飞行行为。这些信息对于理解物种如何应对气候变化至关重要。在更强的顺风条件下，尤其是在觅食返回行程中，所有三个物种的地面速度（即相对于地面的速度）都更高。在更强的逆风条件下，地面速度会降低。南极海燕（；中等体重、最高翼载荷和展弦比）对风速和风向变化的反应比海角海燕（；最低体重、翼载荷和展弦比）或南极鸬鹚（；最高体重、中等翼载荷和展弦比）更强烈。在外出行程中遇到逆风时，鸟类不会根据风向调整飞行方向，也不会调整离巢的最大距离。然而，鸟类似乎会调整往返时间，以便在外出行程中受益于强烈的下坡风作为顺风，并在返回行程中避免强烈的下坡风作为逆风。尽管对可预测的昼夜风况有这些适应性，但鸟类仍经常遇到不利的强逆风，这可能是由于天气系统扰乱了下坡风所致。本世纪剩余时间里，南极近岸风速预计下降将如何影响飞行成本、繁殖成功率以及最终的种群轨迹，仍有待观察。
