Data from: Flap or soar? How a flight generalist responds to its aerial environment

The aerial environment is heterogeneous in space and time and directly influences the costs of animal flight. Volant animals can reduce these costs by using different flight modes, each with their own benefits and constraints. However, the extent to which animals alter their flight modes in response to environmental conditions has rarely been studied in the wild. To provide insight into how a flight generalist can reduce the energetic cost of movement, we studied flight behaviour in relation to the aerial environmental and landscape using hundreds of hours of global positioning system and triaxial acceleration measurements of the lesser black-backed gull (Larus fuscus). Individuals differed largely in the time spent in flight, which increased linearly with the time spent in flight at sea. In general, flapping was used more frequently than more energetically efficient soaring flight. The probability of soaring increased with increasing boundary layer height and time closer to midday, reflecting improved convective conditions supportive of thermal soaring. Other forms of soaring flight were also used, including fine-scale use of orographic lift. We explore the energetic consequences of behavioural adaptations to the aerial environment and underlying landscape and implications for individual energy budgets, foraging ecology and reproductive success.

空中环境兼具空间与时间异质性，可直接影响动物飞行的能耗成本。飞行类动物可通过切换不同飞行模式降低此类能耗，每种飞行模式均具备独特的优势与约束条件。但目前针对野生动物如何依据环境条件调整飞行模式的相关研究仍较为少见。为阐明飞行广适种如何降低运动的能量成本，我们依托数百小时的全球定位系统（Global Positioning System, GPS）与三轴加速度测量（triaxial acceleration measurements）数据，针对小黑背鸥（Larus fuscus）的飞行行为与空中环境、景观格局的关联展开了研究。研究对象个体的飞行总时长存在显著差异，且海上飞行时长随总飞行时间呈线性增长。整体而言，振翅飞行的使用频率高于能量效率更优的翱翔飞行。翱翔概率随边界层高度升高以及离正午越近的时长增加而上升，这反映出支撑热翱翔的对流条件得以改善。研究同时观测到其他类型的翱翔行为，包括对地形抬升（orographic lift）的精细化利用。本研究探讨了针对空中环境与基底景观的行为适应所产生的能量效应，及其对个体能量收支、觅食生态学与繁殖成功率的潜在影响。