F. rufigularis (nat. size).
The following synopsis of the three American species of this subgenus may serve to distinguish them from each other, though only two of them (F. aurantius and F. rufigularis) are very closely related. The comparative characters of the several geographical races of the other one (F. communis), which is cosmopolitan in its habitat, being included under the head of that species, may explain the reasons why they are separated from each other.
Species and Races.
A. First and second quills equal and longest; first with inner web emarginated, second with inner web slightly sinuated. Young with longitudinal stripes on the lower parts. Adult and young stages very different.
1. F. communis. Wing, 11.50–14.30; tail, 7.00–8.50; culmen, .72–.95; tarsus, 1.65–2.20; middle toe, 1.80–2.30.[52] Second quill longest; first shorter than, equal to, or longer than third. Adult. Above plumbeous, darker anteriorly, lighter and more bluish posteriorly; anteriorly plain, posteriorly with darker transverse bars, these growing more sharply defined towards the tail. Beneath ochraceous-white, varying in tint from nearly pure white to deep ochraceous, those portions posterior to the jugulum transversely barred, more or less, with blackish or dark plumbeous; anterior lower parts (from the breast forward) without transverse bars. Young. No transverse bars on the body, above or below. Above blackish-brown, varying to black, the feathers usually bordered terminally with ochraceous or rusty; forehead usually more or less washed with the same. Beneath ochraceous, varying in shade; the whole surface with longitudinal stripes of blackish. Inner webs of tail-feathers and primaries with numerous transverse elliptical spots of ochraceous. Hab. Cosmopolitan.
a. Young dark brown above, the feathers bordered with rusty or whitish. Beneath white or ochraceous, with narrow longitudinal stripes of dusky. Inner webs of tail-feathers with transverse bars.
Auriculars white, cutting off the black of the cheeks with a prominent “mustache.”
Beneath pure white, the breast and middle of the abdomen without markings. Wing, 12.75; tail, 7.30; culmen, .80; tarsus, 2.00; middle toe, 1.80. Hab. Eastern Asia … var. orientalist.[53]
Beneath pale ochraceous, the breast always with longitudinal dashes, or elliptical spots, of dusky; middle of abdomen barred. Wing, 11.50–14.30; tail, 7.00–8.50; culmen, .72–.95; tarsus, 1.65–2.20; middle toe, 1.80–2.30. Hab. Europe … var. communis.[54]