Feather. Light micrograph of part of a feather from the wing of a bird. A bird's feather consists of vanes that have several barbs bearing barbules (thin, hair-like structures) with troughs on one side, which interlock with barbules with hooks on the neighbouring barb. This locks the barbs together, and makes the vane airtight and suitable for flight. The barbules of feathers occasionally become separated but they interlock again when the bird preens its plumage.