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Cynanthus latirostris
The broad-billed hummingbird is a medium-sized hummingbird. It is 9–10 cm long, and weighs approximately three to four grams. Adults are colored predominantly a metallic green on their upperparts and breast. The undertail coverts are predominately white. The tail is darkly colored and slightly forked. The bill of the male is straight and very slender. It is red in coloration, and shows a black tip. His throat is a deep blue. The female is less colorful than the male. She usually shows a white eye stripe. (information from Wikipedia)
This is an immature Broad-billed Hummingbird. Note that the bill is bicolored - in Blue-throated there is no point in which this occurs. Also note the lack of the wide white bar to be expected on the tail for Blue-throated. It is really hard to gauge the size of this bird, though i suspect it would also be too small for Blue-throated. In this particular area of Arizona you are MUCH more likely to encounter Broad-billed as well as Magnificent Hummingbirds having spent a good bit of time in this area photographing hummingbirds. I am very confident of this ID.