The tufted jay (Cyanocorax dickeyi), also known as the painted jay and Dickey's jay, is a species of bird in the crow family Corvidae. It is endemic to a small area of the Sierra Madre Occidental of Sinaloa, Durango, and Nayarit in Mexico. A distinctive large jay, it has a prominent dark crest on its head; purplish blue back, wings, and face; a white spot above the eye and on the cheek; white undersides; and a partially white tail. Its typical call is a quick, four-note vocalization.

The relationship between the tufted jay and other members of the genus Cyanocorax has been a subject of interest since the species was first described in 1935. Because of the visual similarities between the tufted jay and the white-tailed jay, the two were thought by some to be closely related. A 2010 mitochondrial DNA study has shown that the tufted jay is most closely related to a group of South American jays, despite their ranges being separated by over 2,000 km (1,200 mi). They are likely descended from an ancestral jay which ranged throughout Central and South America.

The tufted jay lives in pine-oak forests, often remaining high in the canopy. Its diet consists primarily of berries and fruit, and to a lesser extent insects such as katydids. It forms social flocks centred around a single breeding pair, with some flocks remaining together over several generations. The tufted jay's breeding season starts in late March, with a clutch of two to five eggs being laid in a nest that is cooperatively built by members of the flock. The tufted jay is considered near threatened by the International Union for Conservation of Nature (IUCN). Its population is decreasing, with an estimated 10,000–20,000 mature individuals in the wild. The primary threat to its survival is habitat destruction due to agricultural expansion and deforestation due to logging and narcotic cultivation.

The tufted jay, also known as the painted jay or Dickey's jay, was first described by the ornithologist Robert Thomas Moore in 1935 based on specimens collected on November 7, 1934, near Santa Lucía, Sinaloa, in Mexico. Due to its very limited range, the species was not discovered during previous collection expeditions, despite them passing within 56 km (35 mi) of its habitat. Moore placed it in the genus Cyanocorax and gave it the species name Cyanocorax dickeyi, with the specific name being in honour of the ornithologist Donald Ryder Dickey. The tufted jay has no recognized subspecies.

In his initial description of the tufted jay, Moore noted that its geographically closest relative in the genus Cyanocorax was found in Costa Rica, but that it most closely resembled the white-tailed jay found in Ecuador over 4,800 km (3,000 mi) away. This indicated that the tufted jay and white-tailed jay descended from a common ancestor that once lived throughout Central and South America. This is a commonly held theory by others who have studied the tufted jay. The ornithologist Dean Amadon proposed that the tufted jay was most closely related to its geographically closest relative, the black-chested jay of Costa Rica, and that its similarity to the white-tailed jay was the result of convergent evolution.

These similarities led some researchers to hypothesize that the two must be more closely related than their ranges would suggest. In 1969, the ornithologist John William Hardy discussed a theory that the tufted jay had descended from a flock of white-tailed jays that had accidentally been brought to Mexico by a storm, noting that a similar phenomenon happened to a group of San Blas jays in 1937. In 1979, ornithologist Paul Haemig elaborated on a hypothesis by Jean Théodore Delacour, published in 1944, that the two jays were actually the same species. Haemig said that the colouration differences between the two jays could be explained by Gloger's rule, and that crest size was a "very plastic character in jays" and was of little significance when determining if the two were the same species. He proposed that the white-tailed jay had been brought to Mexico by trade between pre-Columbian societies, and that the tufted jay was descended from that population. A 1989 study of the morphological characteristics of the two species seemed to support these hypotheses by proposing that the two were sister species. In 2010, a mitochondrial DNA study of the genus Cyanocorax demonstrated that the tufted jay and white-tailed jay were not sister species, and that the tufted jay is sister to a clade (a group of species with a common ancestor) formed by the white-naped, Cayenne, plush-crested, azure-naped, and black-chested jays, all of which are found in South America. This study determined that the most likely explanation for the geographical gap between the tufted jay and its South American relatives was due to a widely distributed common ancestor.

The following cladogram (simplified from the 2010 study) shows the relationship between species in the Cyanocorax genus.

The tufted jay is a distinctive bird within its range. It has a crest of black feathers on its head, fading to dark blue at the base. Its face is mostly black to dark blue with white spots above the eyes and white cheeks. It has a white nape and belly. The back and wings are a purplish blue which extends partway down the tail, transitioning to white about halfway down. The beak and legs are both black, and it has bright yellow irises. Immature birds have shorter crests, lack the white spot above their eyes, and have bright blue cheeks and brown irises. This plumage remains until the moult which occurs in their second year. The base of their beak is flesh-coloured, but this fades to black a few months after hatching. There is no difference in plumage or colouration between males and females. The tufted jay's flight is described as "buoyant", and it constantly flaps its wings during flight. The average life span of a tufted jay is not known.