Very large for a hummingbird; size alone separates from many other species. Males and females similar: gray below, dusky-greenish back, brown rump, and large dark tail with prominent white corners. Also note white eyebrow and short white mustache stripe. Male has bright blue throat patch, difficult to see unless the light hits it just right. Uncommon in canyons and mountains with mixed pine-oak forests, primarily in Mexico but barely extending into the U.S. Very similar to Amethyst-throated Mountain-gem, especially if you can’t see the throat color. Blue-throated is slightly larger and paler overall with larger white (not gray) tips on the tail feathers; females are plainer, lacking the buffy tones of Amethyst-throated. Also compare with Rivoli’s Hummingbird, especially females; Blue-throated is shorter-billed and plainer (less speckled) on the underparts.