Supercilium

The supercilium is a plumage feature found on the heads of some bird species.

[1] Also known as an "eyebrow",[1] it is distinct from the eyestripe, which is a line that runs across the lores, and continues behind the eye.

[1] On most species which display a supercilium, it is paler than the adjacent feather tracts.

The dusky warbler's supercilium is sharply demarcated, whitish and narrow in front of the eye, becoming broader and more buffy towards the rear, whereas that of the Radde's warbler is diffusely defined, yellowish and broadest in front of the eye, becoming narrower and more whitish toward the rear.

In some species, such as the jack snipe, the divided stripes reconnect again behind the eye.