Several species of swiftlet produce nests that are edible to man. This nest is that of a Mascarene swiftlet, found on the islands of Mauritius and Reunion. Edible nests are made from saliva, which hardens into a thick gum-like substance when exposed to the air. They are found in dark caves and tunnels, where they are attached to the walls by sticky threads.
There is a long tradition in southeastern Asia of harvesting nests to produce bird’s nest soup, which is considered to be a delicacy. However, rising demand and a growing illegal trade has put the Mascarene swiftlet on the near threatened list at the IUCN list of threatened species.
The photo was taken at the Natural History Museum, Oxford, UK.