Hot footing eggs: thermal imaging reveals foot mediated incubation in White-tailed Tropicbirds, Phaethon lepturus

Abstract

Birds generally incubate eggs by transferring body heat from an exposed abdominal area known as a brood patch. However, there are exceptions to this where some species use foot-mediated incubation. It was previously thought that, although White-tailed Tropicbirds, Phaethon lepturus, lack a brood patch, the heat generated by their feet was too low to incubate their eggs. Using modern thermal imaging techniques, our results indicate the opposite, revealing that tropicbird feet are an important heat source when incubating their eggs.