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 Creek (Wisconsin) are several DNR managed lands, including two areas of glacial habitat restoration. Calamus Creek (Wisconsin) Calamus Creek is a minor tributary of the Beaver Dam River, about long, in southeastern Wisconsin in the United States. Via the Beaver Dam, Crawfish, and Rock rivers, it is part of the watershed of the Mississippi River. Its watershed lies almost entirely within Dodge County with a small portion in neighboring Columbia County. Calamus Creek rises in west central Dodge County near the intersection of Mt. Pleasant and Van Buren roads and follows a highly winding, generally easterly course through Dodge County. It flows