Bird Topography – The Head by Drew Weber
Understanding topography, or the different external features, of a bird is an important step in identifying different closely related species. The head is a good place to start because there are many separate feather tracts that give rise to different physical appearances. The colors of the different feather tracts gives rise to the unique appearance of each species. Below we’ll look over the different characteristics of a birds head along with species that show distinctive features on those tracts.
The crown is the top of the head, and like most other feather tracts, birds can raise and lower these feathers. Some birds have longer feathers on their crown which changes their appearance by giving them a crest like the Northern Cardinal and Tufted Titmouse. Other species without an crest can still raise those feathers, creating a slightly peaked appearance when they are displaying or agitated such as when Ruby-crowned Kinglets flash the usually hidden red feathers in their crown.
The supercillium is the white line that arches over the eye one the Northern Waterthrush, as well as many other species including many of the sparrows. The supercillium runs from the base of the bill to some point near the back of the head. On most species, this supercillium is white, or some lighter color than the surrounding feathers. The shape, color and size of a supercillium can be a key identification in separating confusing species like Northern and Louisiana Waterthrushes.
Eye lines are prominent features on many species. Interestingly this eye line is invariably dark, possibly giving some glare protection to birds, much like the black grease baseball and football players swipe under their eyes. Late in the fall, it can be tricky to separate Orange-crowned and Tennessee Warblers. Looking at the face and seeing an eye line would be a strong indicator of a Tennessee Warbler.
A ring of feathers around the eye, often light in color and very useful for identification. Not all eye-rings are created equal, some species have bold complete eye-rings, while other similar species have a split ring around the eye such as MacGillivray’s Warbler. Eye-rings are particularly useful when you are identifying tricky flycatchers– some show a hint of the eye-ring, others have prominent round eye-rings and some have eye-rings with a tear drop shape towards the back of the eye. These subtle differences can take a while to notice but are crucial to identifying one of these cryptic species if it is not vocalizing.
The auriculars, or ear coverts, are a group of feathers that covers the side of a bird’s head where the bird’s ear openings are located. Several of the warblers such as Blackburnian Warbler show a dark patch in the auriculars and Vesper Sparrow has darker brown feathers that outline the auricular region. The auriculars are a prominent feature on a birds face and therefore probably one of the first things many notice as it defines the face.
The nape goes from the back of the head and lays over some of the upper back feathers. One many birds, the nape blends in with both the back and the rest of the head. However some species have bold napes like the chestnut on a Chestnut-collared Longspur which aid in quick identification when you see it. A group of species where the nape can aid in identification is the sharp-tailed sparrows (in the genus Ammodramus). These small sparrows are secretive and often pop out of the vegetation only briefly, so a look at a purple spotted nape can identify a Le Conte’s Sparrow, an olive-green nape points to Henslow’s Sparrow and a gray nape would narrow it down to Nelson’s, Saltmarsh, and Seaside Sparrow.
Get to know the feather tracts of the face to boost your identification skills when you are out in the field. This knowledge will quickly add to the number of solid features you can use to separate similar looking birds when you might only get a glimpse of them.