Feather Tracts (Pterylae and Apteria) in birds: Explained With Diagrams
Feather Tracts (Pterylae and Apteria) in birds: Major Types and Significance With Diagrams In birds, the sites on the skin, from where the feathers are attached and development of feathers occurs are known as feather follicles. They are just like small indentations. In most birds, the feathers are not attached uniformly over the body, but are grouped into feather tracts called pterylae ( singular: pteryla). Between the tracts are regions of bare or less feathered skin called apteria ( singular: apterium). This arrangement and distribution of feathers in specific tracts over the birds body is called pterylosis . The contour feathers ( pennae) form the general covering of the body. The flightless birds or Ratitae and screamers have feathers uniformly distributed over the body. Ostriches (Family Struthionidae), rheas( Family, Rheidae),emus, cassowaries, penguins ( Family, Spheniscidae)and screamers have feathers uniformly distribute...
