D Glossary of bird terms
a female common eider sits on nest, surrounded down feathers down also, down feathers or plumulaceous feathers. down of birds—their plumulaceous feathers, opposed pennaceous feathers—are layer of fine, silky feathers found under tougher exterior feathers, used humans thermal insulator , padding in goods such jackets, bedding, pillows , sleeping bags. considered simplest of feather types, down feathers have short or vestigial rachis (shaft), few barbs , barbules lack hooks, , (unlike contour feathers) grow both pterylae , apteria. young birds clad in down. loose structure of down feathers traps air, helps insulate bird against heat loss , contributes buoyancy of waterbirds. species experience annual temperature fluctuations typically have more down feathers following autumn moult. there 3 types of down: natal down, body down , powder down. drumming a form of non-vocal communication engaged in members of woodpecker family. involves beak striking hard surface multiple times per second. ...