Wind prevents cliff-breeding birds from accessing nests through loss of flight control.

Emily Shepard,Emmanouil Lempidakis,Andrew Neate,Emma-Louise Cole,Andrew Ross

doi:10.7554/elife.43842

Abstract

For fast-flying birds, the ability to respond to wind during landing is critical, as errors can lead to injury or even death. Nonetheless, landing ability, and its ecological significance, remain unstudied. We show that for auks, 60% of attempts to land at their cliff nests fail in a strong breeze (80% in near-gale winds). This is most likely because wind interferes with the ability to maintain flight control in the last phase of landing. Their extreme flight costs mean that the energetic penalty for multiple landing attempts is high. We propose that exposure, and ability to respond to, such conditions will influence the suitability of breeding habitat. In support of this (i) auk colonies appear to be orientated away from prevailing winds and (ii) landing success within colonies is higher on crowded ledges with more airspace for manoeuvring. More generally, the interplay between wind and flight capacities could impact breeding distributions across species and scales.

Highlights

The ability to fly profoundly affects the ecology of volant species: increasing the speed of travel (Schmidt-Nielsen, 1972), enabling animals to cross substantial barriers (Hawkes et al, 2011; Schmaljohann et al, 2007) and giving enhanced access to space across scales (Kranstauber et al, 2015)
Even for vehicles that move as fast as commercial jets, disturbed wind fields near runways can have a critical impact on flight control and safety, as highlighted by a European Aviation Safety Agency report
Airflow models showed that there was a reduction in the wind speed close to the cliffs compared to the at-sea condition, with substantial areas of reduced wind speed in the lee of Skomer Island (Figure 1A) (Figure 1—figure supplement 1)

Summary

Introduction

The ability to fly profoundly affects the ecology of volant species: increasing the speed of travel (Schmidt-Nielsen, 1972), enabling animals to cross substantial barriers (Hawkes et al, 2011; Schmaljohann et al, 2007) and giving enhanced access to space across scales (Kranstauber et al, 2015). The freedom that flight affords is such that the question of whether or not animals are able to access a given location within their range, or whether this ability is affected by environmental conditions, is almost never considered. In the biological literature, the process of landing has been examined mainly in relation to the sensory processes that guide it (Baird et al, 2013) and the biomechanics of force reduction on impact (Bonser and Rayner, 1996). How either of these may be affected by fluctuations in the wind field that are ubiquitous in the real-world flight environment, and the ecological

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