Synchrony of drinking in Double-banded Sandgrouse,Pterocles bicinctus,at Etosha National Park,Namibia

Double-banded Sandgrouse, Pterocles bicinctus, at Etosha National Park in Namibia exhibit a predictable and remarkably synchronized activity pattern when flying to drink at water-holes. The primary environmental cue that activates this pattern appears to be decreasing light intensity. The species is highly synchronized in this regard, with an average interval of 16 minutes after time of sunset and the time when sandgrouse arrive at water. Birds stay at water for 28 minutes on average. P. bicinctus numbers decrease significantly at artificially supplied water when rain falls. Floodlights have no significant effect on times of arrival or times of departure of these birds at drinking places. The predominantly crepuscular nature of Double-banded Sandgrouse may have evolved as part of their survival strategy by placing them less at risk to diurnal raptors, and may also save energy and reduce evaporative water loss.