Short note on the possible occurrence of heat stress in roosting waders on the Banc d'Arguin, Mauritania

The temperature at the Banc d'Arguin can be very high, and may cause problems of heat regulation in waders originating from the Arctic or Antarctic. A formalin-fixed bar-tailed godwit Limosa lapponica mount exposed to the sun had a temperature of 45°C. The temperature of the mount was higher when placed in a lying position than when it was placed upright. Nevertheless observed bar-tailed godwits, dunlins Calidris alpina and Kentish plovers Charadrius alexandrinus in the high water roost were often lying on the hot sand, and most birds avoided contact with humid (cold) substrates. Only the dunlins stood in the water with their bill tucked under the scapular wing feathers. This behavioral trait is thought to conserve heat, and is also observed in the other bird species in the roosts. Heat stress is apparently not a problem for birds awaiting low tide. -M.Dean