Its plumage is lavender-blue to mid-blue in the crest, back, wings, and tail, and its face is white. The underside is off-white and the neck is collared with black which extends to the sides of the head. The wing primaries and tail are strongly barred with black, sky-blue and white. The bill, legs, and eyes are all black. Males and females are almost identical, but the male is slightly larger.
As with most other blue-hued birds, the blue jay’s coloration is not derived from pigments but is the result of light interference due to the internal structure of the feathers; if a blue feather is crushed, the blue disappears because the structure is destroyed. This is referred to as structural coloration.
The European Starling family, Sturnidae, is an entirely Old World group apart from introductions elsewhere, with the greatest numbers of species in Southeast Asia and sub-Saharan Africa. The genus Sturnus is polyphyletic and relationships between its members are not fully resolved. The closest relation of the common starling is the spotless starling. The non-migratory spotless starling may be descended from a population of ancestral S. vulgaris that survived in an Iberian refugium during an Ice Age retreat.