Steller's jay (Cyanocitta stelleri) is a bird native to western North America, closely related to the blue jay found in the rest of the continent, but with a black head and upper body. It is also known as the long-crested jay, mountain jay, and pine jay. It is the only crested jay west of the Rocky Mountains. It is also sometimes colloquially called a "blue jay" in the Pacific Northwest, but is distinct from the blue jay (C. cristata) of eastern North America.
Steller's jay is about 30–34 cm (12–13 in) long and weighs about 100–140 g (3.5–4.9 oz). Steller's jay shows a great deal of regional variation throughout its range. Blackish-brown-headed birds from the north gradually become bluer-headed farther south. The Steller's jay has a more slender bill and longer legs than the blue jay and has a much more pronounced crest.:69 It is also somewhat larger.
The head is blackish-brown, black, or dark blue, depending on the latitude of the bird, with lighter streaks on the forehead. This dark coloring gives way from the shoulders and lower breast to silvery blue. The primaries and tail are a rich blue with darker barring. Birds in the eastern part of its range along the Great Divide have white markings on the head, especially over the eyes; birds further west have light blue markers and birds in the far west along the Pacific Coast have small, very faint, or no white or light markings at all.
Steller's jay (Cyanocitta stelleri) is one of two species in the genus Cyanocitta, the other species being the blue jay (Cyanocitta cristata); because the two species sometimes interbreed naturally where their ranges overlap in the eastern foothills of the Rocky Mountains, their status as distinct species has been contested. There are 18 subspecies of Steller's jays ranging from Alaska to Nicaragua, with nine found north of Mexico, often with areas of low or non-existent presence of the species separating the subspecies. At least some of the variation in the species is due to different degrees of hybridization between Steller's jays (C. stelleri) and blue jays (C. cristata) . To name a few: