An ostrich is a large flightless bird. It would therefore have more down feathers than contour feathers. Contour feathers are another term for pennaceous feathers which cover the bodies of birds and are involved in flight. These feathers have a central shaft (called the rachis) attached to the skin. Many flat barbs emanate from the shaft that themselves are branched. These barbs are attached each other via barbules. This gives the feathers a highly ordered, mesh-like structure that provides support against wind resistance in flight. Down feathers lack this structural support and are much fluffier and softer. They are primarily for warmth and insulation. It should be noted, however, that the primary reason for ostriches not being able to fly has less to do with feather types and more to do with their size and weight.