Feather These barbules have minute hooks called barbicels for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation. At the base of the feather, the rachis expands to form the hollow tubular "calamus" (or quill) which inserts into a follicle in the skin. The basal part of the calamus is without vanes. This part is embedded within the skin follicle and has an opening at the base (proximal umbilicus) and a small opening on the side (distal umbilicus). Hatchling birds of some
Calamus Swamp Calamus Swamp Calamus Swamp is a public preserve located from Circleville in Pickaway County, Ohio, United States. It has a natural kettle lake/wetland and is owned by the Columbus Audubon, the local chapter of Audubon. Calamus Swamp includes the only known kettle lake in Central Ohio that is naturally vegetated and undisturbed. The kettle lake was made in the last ice age by the glacier that covered 2/3 of Ohio. When Ada May Burke and Sally V. May got the land, they donated it to Columbus Audubon, who then made it into a public preserve. According to the Columbus Audubon