Airflow modelling predicts seabird breeding habitat across islands.

Emily L C Shepard,Luca Börger,Emmanouil Lempidakis,Andrew N Ross

doi:10.1111/ecog.05733

Abstract

Wind is fundamentally related to shelter and flight performance: two factors that are critical for birds at their nest sites. Despite this, airflows have never been fully integrated into models of breeding habitat selection, even for well-studied seabirds. Here, we use computational fluid dynamics to provide the first assessment of whether flow characteristics (including wind speed and turbulence) predict the distribution of seabird colonies, taking common guillemots Uria aalge breeding on Skomer Island as our study system. This demonstrates that occupancy is driven by the need to shelter from both wind and rain/wave action, rather than airflow characteristics alone. Models of airflows and cliff orientation both performed well in predicting high-quality habitat in our study site, identifying 80% of colonies and 93% of avoided sites, as well as 73% of the largest colonies on a neighbouring island. This suggests generality in the mechanisms driving breeding distributions and provides an approach for identifying habitat for seabird reintroductions considering current and projected wind speeds and directions.

Highlights

Reproductive success is closely linked to the physical characteristics of breeding sites in many taxa (Birkhead et al 1985, Harris et al 1997)
In order to assign slope angles and wind parameters to each section, the survey was digitized in ArcMap 10.5.1 (ESRI, Redlands, California), and horizontal section boundaries were mapped onto a digital elevation model (DEM) (50-cm resolution retrieved from Lle Geo-Portal )
Wind regimes are changing in terms of the mean strength and the frequency of extreme weather events (Young et al 2011, Young and Ribal 2019)

Summary

Introduction

Reproductive success is closely linked to the physical characteristics of breeding sites in many taxa (Birkhead et al 1985, Harris et al 1997). In colonial animals, breeding sites can represent the nexus of reproductive activity for tens of thousands of individuals (Buckley and Buckley 1980). Seabirds are more at risk than other comparable groups of birds, with a widespread decline in populations due to commercial fisheries, pollution, habitat change and the introduction of invasive predators (Croxall et al 2012). In some cases, this has led to entire

Methods

Results

Conclusion