Birds of the World

Anhingidae : Darters

African Darter

Anhinga rufa

African Darter (Anhinga melanogaster rufa) drying its feathers in the sun - Abuko, The Gambia - January 2003

Similar to cormorants, the Darter and Anhinga quickly become waterlogged when swimming and diving in the water due to an intrinsic porisity in the microscopic structure of their feather.  Darters become even more comprehensively waterlogged than cormorants, due to a lack of an insulating layer of air next to the skin present in cormorants.  This results in a very low profile when swimming on the surface, with only their narrow, snake-like neck and head visible above the surface, and gives rise to their alternative name of "snake-bird".   Although not having waterproof feathers may appear to be a disadvantage in an aquatic bird, the resulting loss of buoyancy makes diving and swimming underwater much easier.