... Sections . ... Division of Exhibition . ... Atlas "Birds of Moscow City" . Monitoring of common birds . ... History of the Section . ... Collections . ... Bird collections . ... It is an acknowledge opinion that the bird feathers arose evolutionary from horny scales of their reptile ancesotrs, primarily as a thermal insulation coating. ... With a few exceptions, the avian body is covered with feathers unevenly, as they grow only in certain areas called pteriliyas, alternating with naked aptera. ...