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

Abstract

One contribution of 17 to a theme issue 'Moving in a moving medium: new perspectives on flight'. 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.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

Intercolony variations in movement patterns and foraging behaviors among herring gulls (Larus argentatus) breeding in the eastern Wadden Sea

“…Previous studies demonstrated that flights over land consumed less energy than expected, and flight costs were reduced using fine‐scale structures (e.g., dykes) to increase orographic lift (Shamoun‐Baranes, Bouten, van Loon, Meijer, & Camphuysen, 2016; Shepard, Williamson, & Windsor, 2016). Furthermore, birds prefer foraging habitats with predictable prey distributions during the breeding season (Camphuysen, 2013; Weimerskirch, 2007), as expected in terrestrial habitats (Gorke & Brandl, 1986; Palm, van Schaik, & Schröder, 2013; Sibly & McCleery, 1983).…”

The characteristic time‐scale of perceived information for decision‐making: Departure from thermal columns in soaring birds

“…While Eurasian griffon vultures use mostly passive soaring flight, other bird species vary their use of powered and passive soaring flight (Shamoun‐Baranes, Bouten, van Loon, Meijer, & Camphuysen, ; Taylor et al., ; Weimerskirch, Bishop, Jeanniard‐du‐Dot, Prudor, & Sachs, ). For species that change their flight mode frequently, the additional time‐related decisions are likely related to the frequency of powered flight and the individual‐specific power curve.…”

Meteorological and environmental variables affect flight behaviour and decision‐making of an obligate soaring bird, the California Condor Gymnogyps californianus

“…, Shamoun‐Baranes et al . ). Wind speed and direction can influence the development of both thermal and orographic updrafts and can affect a bird's airspeed (Shamoun‐Baranes et al .…”

“…, Shamoun‐Baranes et al . ). Over terrestrial landscapes, the two most common types of air movements relevant to flying animals are thermal and orographic updrafts (but see Mallon et al .…”