The Challenge of Coping in an Extremely Hot Environment: a Case Study of the Incubation of Lesser Crested Terns (Thalasseus bengalensis)

The Lesser Crested Tern (Thalasseus bengalensis) is a ground-nesting seabird that breeds only on subtropical and tropical islands from northern Africa to northern Australia. Despite their wide distribution, few studies have been conducted on the breeding ecology of this species. On Jana Island, Saudi Arabia, which is northeast of the Saudi Arabia mainland, the midday ground temperature may reach 60 degrees C during the summer. In this study, two cameras were used to record the incubation behavior of Lesser Crested Terns to evaluate their coping ability in this extremely hot environment. The behavioral mechanism that the seabirds used to maintain optimal egg temperatures was also evaluated. The results show that Lesser Crested Terns attend their eggs continuously during a 24-hr period without leaving the nests, except when a disturbance occurs. This behavior prevents the eggs from reaching lethal temperatures. In addition, position of the sun influenced the incubation behavior. Most incubating Lesser Crested Terns faced west in the morning, and began rotating clockwise until they faced east in the evening. This behavior may play a vital role in preventing both eggs and incubating adults from overheating.