The supercilium is a

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

feature found on the heads of some

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

species. It is a stripe which runs from the base of the bird's

beak The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for pecking, grasping, and holding (in probing for food, eating, manipulating and ...

above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also known as an "eyebrow", it is distinct from the eyestripe, which is a line that runs across the lores, and continues behind the eye. Where a stripe is present only above the lores, and does not continue behind the eye, it is called a supraloral stripe or simply supraloral. On most species which display a supercilium, it is paler than the adjacent feather tracts. The colour, shape or other features of the supercilium can be useful in bird identification. For example, the supercilium of the

dusky warbler The dusky warbler (''Phylloscopus fuscatus'') is a leaf warbler which breeds in the east Palearctic. The genus name '' Phylloscopus'' is from Ancient Greek ''phullon'', "leaf", and ''skopos'', "seeker" (from ''skopeo'', "to watch"). The specific ...

, an

Old World warbler The Old World warblers are a large group of birds formerly grouped together in the bird family Sylviidae. They are not closely related to the New World warblers. The family held over 400 species in over 70 genera, and were the source of much taxo ...

species, can be used to distinguish it from the very similar

Radde's warbler Radde's warbler (''Phylloscopus schwarzi'') is a leaf warbler which breeds in Siberia. This warbler is strongly migratory and winters in Southeast Asia. The genus name ''Phylloscopus'' is from Ancient Greek ''phullon'', "leaf", and ''skopos'', ...

. 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. The supercilium of the

northern waterthrush The northern waterthrush (''Parkesia noveboracensis'') is a species of ground-feeding migratory New World warbler of the genus ''Parkesia''. It breeds in the northern part of North America in Canada and the northern United States including Alask ...

, a

New World warbler The New World warblers or wood-warblers are a group of small, often colorful, passerine birds that make up the family Parulidae and are restricted to the New World. The family contains 120 species. They are not closely related to Old World warb ...

, differs subtly from that of the closely related (and similarly plumaged)

Louisiana waterthrush The Louisiana waterthrush (''Parkesia motacilla'') is a New World warbler, that breeds in eastern North America and winters in the West Indies and Central America. Plain brown above, it is white below, with black streaks and with buff flanks and ...

. The Louisiana has a bicoloured supercilium which widens significantly behind the eye, while the northern has an evenly buffy eyebrow which is either the same width throughout or slightly narrower behind the eye. A split supercilium divides above the lores. In some species, such as the

jack snipe The jack snipe or jacksnipe (''Lymnocryptes minimus'') is a small stocky wader. It is the smallest snipe, and the only member of the genus ''Lymnocryptes''. Features such as its sternum and its continuous 'bobbing up and down' make it quite dis ...

, the divided stripes reconnect again behind the eye. In others, such as the

broad-billed sandpiper The broad-billed sandpiper (''Calidris falcinellus'') is a small wader, wading bird. The scientific name is from Latin. The specific name ''falcinellus'' is from ''falx, falcis'', "a sickle." Some research suggests that it and some related spec ...

, the divided stripes remain separate. A supercilium drop is a feature found on some

pipit The pipits are a cosmopolitan genus, ''Anthus'', of small passerine birds with medium to long tails. Along with the wagtails and longclaws, the pipits make up the family Motacillidae. The genus is widespread, occurring across most of the world, ...

s; it is a pale spot on the rear of the which, although separated from the supercilium by an eyestripe, can appear at some angles to be a downward continuation of the supercilium.

Gallery

File:Wilsonia canadensis.jpg, The

Canada warbler The Canada warbler (''Cardellina canadensis'') is a small boreal songbird of the New World warbler family (Parulidae). It summers in Canada and northeastern United States and winters in northern South America. Taxonomy In 1760 the French zoolog ...

shows a yellow supraloral. File:Limicola falcinellus Taiwan cropped.jpg, The

has a split supercilium... File:Lymnocryptes minimus (Marek Szczepanek).jpg, ...as does the

. File:Olive-backed Pipit- Kolkata I IMG 9872.jpg, The olive-backed pipit has a supercilium drop.

References

Notes

Sources

* * {{Feather-tracts Bird anatomy Feathers