Pica is the genus of three species of birds in the family Corvidae in both the New World and the old. They have long tails and have predominantly black and white markings. One species ranges widely from Europe through Asia, one occurs all over North America and the third is restricted to California. They are usually considered closely related to the blue and green magpies of Asia, but recent research (Ericson et al., 2005) suggests their closest relatives are instead the Eurasian crows.
Two or three species were generally recognized, the Yellow-billed and one or two black-billed ones. Recent research has cast doubt on the taxonomy of the Pica magpies (Lee et al., 2003). P. hudsonia and P. nuttalli are each other's closest relatives, but may not be different species. If they are, however, at least the Korean race of P. pica would have to be considered a separate species, too.