Black-billed Magpie - Systematics and Evolution

Systematics and Evolution

Externally, The Black-billed Magpie is almost identical with the European Magpie, Pica pica, and is considered conspecific by many sources. The American Ornithologists' Union, however, splits it as a separate species, Pica hudsonia, on the grounds that its mtDNA sequence is closer to that of California's Yellow-billed Magpie, Pica nuttalli, than to the European Magpie. If this view is correct, the Korean subspecies of the European Magpie, Pica pica sericea, should also be considered a separate species.

It appears that after the ancestral magpie spread over Eurasia, the Korean population became isolated, at which point the species crossed the Bering Land Bridge and colonized North America, where the two American magpies then differentiated. Fossil evidence indicates that the ancestral North American magpie had arrived in its current range around the mid-Pliocene (3-4 mya) and that the Yellow-billed Magpie lineage split off rather soon thereafter due to the Sierra Nevada uplift and the beginning ice ages. A comparatively low genetic difference, however, suggests that some gene flow between the Black-billed and Yellow-billed magpies still occurred during interglacial periods until the Pleistocene.