Two of the commonest hummingbirds (and no others) in Minas Gerais, Brazil, have a tail that look somewhat like the bird on the photograph.
1) Swallow-tailed Hummingbird (male and female are alike).
2) Violet-capped Woodnymph (male. Female is more sombre in colouration, and doesn't have the forked tail).
Have a look at photographs on these two pages:
http://www.arthurgrosset.com/sabirds/violet-capped woodnymph.html
http://www.arthurgrosset.com/sabirds/swallow-tailed hummingbird.html
Obviously the bird on the photo by Deca isn't adult. The white leg-tufts can be somewhat confusing, as they are found in ad. males of the Woodnymph but not in ad. Swallow-tailed. However, yet again, it's an imm. bird and I have seen juv. Swallow-tailed with white. None of the two species have tufts on the shoulder as adult. So, what then? If looking at the overall jizz, it is clear that it's a Swallow-tailed. Similarly, for a bird with so many imm. features, the tail is to long for it being the Woodnymph. Finally, the shape of the tail and the dept of the fork once again points toward Swallow-tailed (even though it will be much larger when fully grown). So, it's an imm. Swallow-tailed Hummingbird.
When fully adult the two species are easy to seperate both on colours and tail. Also remember that Swallow-tailed is one of the "big" hummers, being much larger than Violet-capped.
I guess Deca got confused by the reddish behind the eye... Be carefull with such "red spots". Sometimes when looking closer I have discovered it was nothing but a red mite! Having said that, both Swallow-tailed & Violet-capped often show such a small patch. The violet patch is very different in White-vented Violetear+tail is totally different.
Added later: Just in case people wonder how the Violetear look, her's a link:
http://www.arthurgrosset.com/sabirds/white-ventedvioletear.html