Transvolcanic Jay is similar to Mexican Jay (Aphelocoma wollweberi), and indeed until recently Transvolcanic Jay was classified as a subspecies group of Mexican. Transvolcanic Jay is larger than Mexican Jay, and the upperparts of adult Transvolcanic Jay are deeper, more purplish blue than in Mexican. The bill of adult Transvolcanic Jay is black, but the bill of the fledgling is pale (pinkish or yellowish), and may take up to three years to turn completely black. Transvolcanic Jays occupy pine-oak forests and have large social groups, suggesting that it may be a cooperative breeder; but, in contrast to the northern populations of Mexican Jay in Arizona, which have been studied extensively, little is known about the biology of Transvolcanic Jay.