Behavioural mechanisms employed by adult black-winged Stilts to mitigate heat stress in the hot environment of the eastern coast of Saudi Arabia

Abstract

The Black-winged Stilt (Himantopus himantopus) is a widely distributed ground-nesting wader species found across most continents, except for the northern Nearctic and far eastern Palearctic. This species breeds in a variety of wetland habitats, from coastal marshes to inland lagoons. However, in regions with extreme climates, particularly during the breeding season, Black-winged Stilts may encounter some environmental challenges. This study focuses on the behavioural mechanisms employed by adult Black-winged Stilts to mitigate excessive heat stress on eggs at the Sabkhat Al-Fasl Lagoons, located on the eastern coast of Saudi Arabia. The harsh climate of the study site, characterized by high ground temperatures, significant day-night temperature fluctuations, and intense sunlight during the summer months, presents challenges that may influence the incubation behaviours of the incubating adults. The results showed that nest attendance remained consistently high, averaging 95.18 ± 1.86% throughout the day. Black-winged Stilts maintained egg temperatures within a range of 31°C to 40°C. During the hottest parts of the day, incubating parents exhibited continuous nest attendance, rarely leaving the nest for even a minute. Moreover, the orientation of the incubating adults was influenced by the position of the sun. Specifically, parents tended to avoid facing the sun while incubating, likely to minimize the eggs’ exposure to direct sunlight and reduce the risk of overheating. By documenting these adaptive responses, the study enhances our understanding of how this species copes with extreme heat. Given the rising temperatures linked to global climate change, further behavioural data from other populations of this species—both within the Arabian Peninsula and across its broader distribution—would be crucial for understanding the species’ phenotypic plasticity and its ability to adapt to changing environmental conditions.