Video S2: from Structure and mechanics of water-holding feathers of Namaqua sandgrouse (Pterocles namaqua)

A dry sandgrouse belly feather is fully immersed in water using tweezers to hold it at the root of the shaft. Upon immersion, the barbules in the outer zone splay outwards, while those in the inner zone form a forest-like network perpendicular to the original plane of the vane on the ventral side. When taken out, the barbules in the outer region curl inwards, encapsulating the water, while the barbules in the inner region roughly maintain their orthogonal orientation. Specimen #142928, Museum of Comparative Zoology, Harvard University © President and Fellows of Harvard College.