He's an Anna's Hummingbird- a beautiful, tiny little guy- with attitude. Named after Princess Anna Massena, the dutchess of Rivoli, who was obviously a bit of a looker. Audubon wrote that she was a "... beautiful young woman, not more than twenty, extremely graceful and polite" (Audubon and his Journals I, 1897, p. 314: I got it from Palmer. 1928, The Condor Volume 30, pp. 261-307).
He is also the fastest animal on the planet! Flying at 385 body lengths per second, they reach speeds of around 50mph during their flying displays- reaching G-forces that humans could not endure.
Well, an obvious first answer is a cultural service- because many people, including myself, simply love these little birds and appreciate them for just being them. There may also be an economic role to play because birdwatching is a multi-million dollar industry and people will traveling to see an Anna's hummingbird (they are pretty common around California).
But I'm interested in how bird foraging might be important for us- so, what does a hummingbird eat? Flower nectar, of course! (any kindergarten student knows that one!) Meaning that hummingbirds play a role in pollination services. Hummingbirds, especially Anna's, may also provide insect pest-control services- because hummingbirds eat insects as well as nectar! Hummingbirds are adept at catching insect prey, and rely on insects for important nutrients that they cannot gain from nectar sources. Watch the amazing video below of how Anna's hummingbirds hunt for insect prey. As far as I can tell, the importance of hummingbirds as a control agent of insect pests is unknown- probably because it's so hard to study these tiny creatures!
The degree of pigmentation (color) and reflectance in the iridescent magenta feathers of the crown of the Anna's is actually dictated by the amount of protein in their diets. Hummingbirds in general are considered to be a protein-limited group because of their tendency to eat nectar, which is high in sugar but low in protein, and because of their incredibly high metabolism. The authors of the study linked above thought that because males need to hover while capturing insect prey- which is a very high energy activity but one with a high protein payout if they succeed in capturing an insect- feather hue and iridescence could be viewed by prospective females as an honest signal of the worthiness of potential mates. If a male is fit enough to capture plenty of insects, he's probably going to be a good dad and pass along those genes to his offspring.
In a study published in The Proceedings of the Royal Society- Biological Sciences, Chistopher Clark & Teresa Feo showed that male Anna's Hummingbirds are able to produce this incredibly loud sound, using the fast vibrations of parts of stiff outer tail feathers at the astonishing speeds that are reached at the bottom of display dives. The study first took film and audio recordings of male hummingbirds displaying for dummy female hummingbirds, where they produced the chirp at the bottom of their flights. The researchers then caught the males and either trimmed or removed their outer retrices (the technical word for tail feathers). On subsequent display flights, the hummingbirds didn't produce the chirping sound. Don't worry, the birds grew back their tail feathers in 5 weeks. In wind tunnels, the scientists were able to confirm that the fluttering of part of the outside tail feathers creates the chirping sound, and have since been able to show it in a number of other displaying hummingbird species. The youtube clip below from Chris Clark's channel explains the physics of this phenomenon:
Cornell Lab of Ornithology's fantastic 'All About Birds' site has great facts, images, and media files. I love the facts about hummingbirds- did you know that a group of hummingbirds is called a "bouquet, a glittering, a hover, a shimmer, or a tune of hummingbirds." Awesome.