Airflow modelling predicts seabird breeding habitat across islands

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.

Factors determining nest‐site selection of surface‐nesting seabirds: a case study on the world's largest pelagic bird, the Wandering Albatross (Diomedea exulans)

“…This is probably because this species needs strong enough wind speeds to take-off and land (making very wind-sheltered locations unsuitable), but also benefits from protection from the strongest wind speeds, both for thermoregulation and for chicks not to be blown off their nests. This influence of flight-related wind preferences impacting nest-site selection is in agreement with those for a cliff-nesting seabird species on much smaller islands, where Common Guillemots are only able to land in very low wind speeds, and therefore nest in more sheltered locations (Shepard et al 2019, Lempidakis et al 2022.…”

“…In other systems, the windward sides of nests have trampled vegetation where the birds enter the nest (Miller et al 2014). Common Guillemots Uria aalge (Alcidae), a cliff-breeding seabird, nest in areas that are protected from wind and rain and waves, which are also affected by the wind characteristics (Lempidakis et al 2022). Wind is being recognized as an important factor for seabirds, affecting their movement (Weimerskirch et al 2000, Clay et al 2020, foraging ecology (Cornioley et al 2016), predation (Gilchrist & Gaston 1997) and even life-history (Weimerskirch et al 2012).…”