The common oriole around here, a summer resident, is the Bullock's Oriole, a mostly orange bird with a black back and top of the head, large white wing patches and yellow on its tail. You can see one at www.nps.gov/whsa/bird%20list/Bullock%92s%20Oriole.htm
In my old Peterson field guide, published in the '60s, the Bullock's is presented as a full species. However, during much of my birding life newer field guides have lumped the Bullock's, a western species, with the Baltimore Oriole, an eastern species, under the name of Northern Oriole. Well, recently they re-split the species, so we're back to having Bullock's and Baltimore Orioles again.
What happened is that in the old days when people began planting trees in the Plains States the two rather different-looking "species" come together and hybrid birds occurred with intermediate characteristics. "Species" are supposed to be genetically isolated entities, so Bullock's and Baltimores were lumped. However, lately it's been noted that, despite the hybrids, many birds in the overlapping areas choose their own kind to mate with, so now the common wisdom is that they're more distinct than they are the same.
Well, this just shows how slippery is the whole taxonomic concept of "species." Fact is, Mother Nature makes no effort at all to make Her creations fit the neat little pigeonholes we humans have thought up.
Moreover, when you top off the above insights with the fact that nowadays they're inserting pieces of genetic code from animals such as fish into the genetic makeup of certain plants, and those plants are doing just fine, just showing certain fishy traits, you realize that the taxonomy of nature is a bit more squishy than maybe we'd like to believe.