A crow by any other name would . . .
Only slightly smaller and with a huskier voice, the northwestern crow resembles the American crow to a remarkable degree. Some professional ornithologists go so far as to say they are the same species. Even so, distinct differences are apparent. Northwestern crows inhabit the coastal lowlands of the Pacific Northwest, only moving inland along major rivers during salmon runs. They feed on a variety of tidal organisms such as crabs, clams, and snails, and they scavenge dead fish. Northwestern crows can be seen cracking open shellfish by dropping them from the air onto rocks below, much as seagulls do.
Lewis made a point to say the crows he observed along the Columbia estuary were smaller than the usual crows he saw across the country (American crows), but otherwise the same species. It takes a seasoned birder to distinguish the two crows. Better than a novice birder, Lewis was not at the level of a professional.
The explorers actually saw three types of crows during their long journey - the American crow, the northwestern crow, and the common raven.