The feather microstructure of Passerine sparrows in China

SummaryWhile the microstructures of bird feathers have long been considered to be of taxonomic significance at the level of orders and families, this paper reveals the eco-morphological significance of feather structures in the snow sparrow complex (Montifringilla/PyrgilaudalOnychostruthus spp.), the Rock Sparrow (Petronia petronia) and the House Sparrow (Passer domesticus). Among these three groups, the node shape, node density, and villi structure might be diagnostic. The less developed interlocking system of the pennaceous barbs, the specialised node shape and a high node density in the downy barbules of the snow sparrow complex result in a thick fluffy plumage with more air isolation and thus better thermal insulation.