Even though I'm not one of the Anna's voters, I'd like to further respond anyway to a couple things mentioned by Charles and others.
Our black-chinneds and broad-taileds have already fledged their first brood and have left. We're in the "lull" between broods of these two spp, of which we usually get two per year. I don't know for certain if the rufous, which have yet to arrive, have ever fledged two clutches in a single season. So although we're southeast of southeast Oregon (I'm in northeast AZ), we're still at 7,000 ft. and have a similar "timetable" for breeding season as points farther north. So it may or may not be "too early" for immature BCHU to show up in southeast Oregon. As BCHU breeds throughout the western US from Mexico to Canada (except for extreme western OR, WA and northern CA), this bird in SE OR could be from anywhere and not from one of the Fields broods.
Ruby-throated hummingbirds do not occur west of the Rocky Mountains except for about a half-dozen records ever, and none of those are in Oregon (as far as I know -- someone please correct me).
Black-chinned's wings are not "bulbous" on the ends, they're simply broader and less delicate looking than most other hummer spp, and not tapered. But to characterize them as "bulbous" or "club-ended" on the ends is way over-stating the case. They may have that appearance in the hand with the wings spread out and each feather flattened, but they do not have that appearance perched or in flight. At least none of the hundreds we've had here in our back yard at the feeders and in the trees show this characteristic.
This bird also exhibits the exact description Sibley uses for BCHU juvies: "grayer crown and auriculars contrast less with throat" [than does Anna's, whose auriculars are darker gray and more contrasting to the throat]. Anna's is also much greener on the forehead and crown than BCHU; the bird in question has far more gray than green.
Of all the Anna's I'd seen over a 7-year period of birding in southern CA when I lived there, none of them (to my recollection) ever exhibited the slightest bit of curve to the bill. The bills were short and looked like little straightpins (if I may borrow a sewing notion).
I also meant to ask earlier if this bird's eye was "sleepy" or "weepy"? Does it look to anyone else like both upper and lower lids are slightly swollen and the squinty-eyed appearance is due to an irritation or infection of some kind? Perhaps I've been seeing too many house finches with infected eyes this year (for the first time) so I look for the boogey man everywhere now.
Sorry, but I just don't see anything to point to Anna's and everything to indicate BCHU. Okay, I'll shut up now and give the floor back to you Anna's voters.