pteryla

anatomy

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July 13, 2026

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The term "pteryla" refers to one of the distinct areas on a bird's skin where feathers grow. These feather tracts, known as pterylae, are separated by bare areas called apteria. While it may appear that birds are evenly covered in feathers, they actually grow in these specific patterns. This arrangement of feathers, or pterylosis, is an important characteristic used in classifying birds. The word "pteryla" originates from Greek words meaning "feather" and "wood" or "forest".123

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integument
Birds
…arranged in feather tracts (pterylae) separated from one another by regions 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…
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…arranged in feather tracts (pterylae) separated from one another by regions 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…
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passeriform
Plumage and pterylosis
…from relatively narrow tracts (pterylae) in the skin. From the pterylae the feathers fan out and cover the remainder of the bird’s body. In passerines, the feathers are arranged in eight distinguishable tracts, with apteria (relatively bare skin) between them. Variations in tract width and length and especially differences…
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…from relatively narrow tracts (pterylae) in the skin. From the pterylae the feathers fan out and cover the remainder of the bird’s body. In passerines, the feathers are arranged in eight distinguishable tracts, with apteria (relatively bare skin) between them. Variations in tract width and length and especially differences…
Read More