(noun) A distinct line or arch of contrasting feathers above a bird's eye. Eyebrows generally start above the lores and go well past the back of the eye, but the length, width and shape of the brow can vary depending on the bird species. Color can also vary, but in many birds the eyebrows are lighter than the surrounding plumage. Eyebrows are a common field mark and some bird species from all types of birds will show clear eyebrows.
To identify a bird with an eyebrow, note the length, color, shape, width and position of the brow. Also note whether the eyebrow changes shape or color along its length, whether the edges are sharp or blurred and compare it to other head and facial field marks such as the crown, lores, forehead and cheeks. Take care not to confuse eyebrows with eye lines, which go through the eye rather than above it.
Photo – Northern Waterthrush © brian_mcclure0422
Brow, Supercilium, Superciliary Line