When I was looking for a link for my last magpie post, I discovered that some sources gave the Latin name for the black-billed magpie as Pica pica, and others used Pica hudsonia. Huh? Maybe the magpie is just being a trickster again - or maybe it is the scientists who decide taxonomic names trying to confuse innocent bird-watchers again.
The Integrated Taxonomic Information System, a very official-looking site with more about taxonomy than you ever wanted to know, notes obliquely that Pica pica hudsonia is the old name and the bird is now called pica hudsonia; that looks like a subspecies became a species at some point between 1823 and now. According to Wikipedia, the black-billed magpie is externally "almost identical with European Magpie, Pica pica, and is considered conspecific by many sources. The American Ornithologists' Union, however, splits it as a separate species, Pica hudsonia"; that would be a change in species, not a subspecies, and I am still confused.
Finally, I found some real help in the Montana Audubon website: In the winter of 2002, it noted that, "on the basis of morphological, behavioral, and genetic characters, the Black-billed Magpie in North America is considered a distinct species from that in the Old World. The English name for our magpie does not change, but the scientific name becomes Pica hudsonia . The Old World bird becomes Eurasian Magpie and retains the scientific name Pica pica ." So the confusion starts with the trickster magpie, which confuses the taxonomists, who confuse me. Got it.