apterium

avian physiology

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June 18, 2026

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An apterium is a bare space between the feathered areas on a bird's body. These bare areas, known as apteria, are part of the feather tract system, called pterylosis, where feathers grow in distinct lines on the skin. The feathered areas are called pterylae. The term "apterial" is an adjective meaning "of or relating to an apterium". This arrangement of feathered tracts and bare spaces is a characteristic feature of avian anatomy.1234

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integument
Birds
…of almost naked skin (apteria). The only exceptions are the ostrichlike birds, the penguins, and the South American screamers, in which the even distribution of plumage has probably been secondarily acquired. Feather tracts differ in arrangement in different species and hence are useful in the classification of birds.
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…of almost naked skin (apteria). The only exceptions are the ostrichlike birds, the penguins, and the South American screamers, in which the even distribution of plumage has probably been secondarily acquired. Feather tracts differ in arrangement in different species and hence are useful in the classification of birds.
Read More