The “Wings” of the Air Guard:

1) Solar Wing, the traditional white coat/golden armor Pegasi stallions that serve Celestia. They, like their Princess, watch over the day, and rise with the sun each morning.
2) Lunar Wing, comprised of the rare, nocturnal bat-winged stallions that serve Luna. Predictably, they watch over the night, and rise with the moon.
3) Dusk Wing, an eclectic mix of ponies, with mare and stallion Pegasi of many different talents, several bat-winged Guards who used to work for Luna, and a few Griffons thrown in for good measure. Despite their varied origins, this small group of fliers is very tight-knit, and completely loyal to Twilight Sparkle. Also, because their Princess is not technically part of the day/night cycle, Dusk Wing acts on a very case-by-case basis, and is the most likely to, say, chase down some thieves in a ponyhunt, or have its members go undercover in places like the Undercloud of Los Pegasus.

All three are lead by a Wing Commander, who is directly appointed by, and reports directly to, each respective Princess. The Air Guard’s Unicorn and Earth counterparts are known as the Magic Guard and Ground Guard, respectively, and are similarly separated by princess (the separate groups are known as Solar Horn, Solar Hoof, Lunar Horn, Lunar Hoof, Dusk Horn and Dusk Hoof). In general, the three Solar, Lunar and Dusk groups cooperate, but only within their spheres (e.g. Lunar Horn never watches the day, but it does work together with Lunar Hoof and Lunar Wing to patrol the night).

All together, these three branches (Air, Ground and Magic) comprise the full Equestria Royal Guard, which answers to the Princesses collectively, but there hasn't been an event that required all of the forces of the Guard at the same time since before Twilight's coronation (the last one was Discord's return).

(This is simply a sketch I found when I was looking for images, I did not draw it. Here's who did. :) Yay for deviantArt)

Taller than the average pony, and quite a bit larger, with powerful wings, a muscular body and piercing brown/red eyes, an angry Lt. Commander Red can be very intimidating. Luckily, when she isn’t on duty she’s quite easygoing, which helps the ponies around her get used to the talons and everything (she keeps those suckers sharp). Rosie’s eagle half is that of a Golden Eagle (check out these example pictures for reference), with dark brown plumage on her chest, but auburn covering the top and back of her head, from her beak up to the long feathers on top (the tips of which are a light tan). Similarly, at her shoulders her wings are dark brown, but they turn to mottled auburn/tan as you move along them, ending with distinctive red tips on her longest flight-feathers (the basis of her name).

The Griffon’s lion half (and front legs) are simply a lighter shade of brown up to the tuft, which is dark brown where it meets the tail, but gradually gets redder, until it matches the tips of her wings. The only remnant of her usual outfit as an officer of Twilight’s Dusk Wing is the purple headband (it’s the same shade as Twilight’s coat).

Though she doesn’t know it, Rosewing Red was the product of a series of political intrigues in the far-off Griffon Kingdoms, and was abandoned in Cloudsdale as a chick in an act of revenge. Her parents (not nobility themselves) had betrayed a Griffon Duke, and when he discovered the treachery he had his soldiers abduct their newly-hatched daughter, and told them to take her wherever they wished, as long as it was beyond the Kingdoms. He wasn’t a particularly cruel Griffon, and would never order them to kill the chick, but when she disappeared, her parents went berserk and attempted to attack the Duke, believing he had killed her. Thus, by the laws of the Kingdoms, they were imprisoned, and imprisoned they remain.

Far, far away from the ancestral homeclouds of the Griffons, across the sea, the nameless chick was dropped on a random doorstep in Cloudsdale, and left to fend for itself. Luck, it would seem, was on the chick's side, as that doorstep belonged to Ruby Tears, a Pegasus pony renown for her compassion. Indeed, the newly-named Rosewing Red was taken in at once, and became an official member of the sprawling Red clan. She was taught to control her predatory instincts, eating only unintelligent creatures, such as fish, and, most importantly, her adopted mother and several uncles and aunts soon taught her how to fly. From there, she grew quickly into adulthood, training her body and wings, reveling in the joy of flight.

Those suppressed urges caught up with her, however, and over time Rosie subtly became aggressive, picking fights with big stallions just to prove she could beat them up, stealing things just so she could outfly anyone who tried to chase her, and one day, she actually lashed out at a pony with her talons during an argument, and gashed open his flank! The poor stallion eventually recovered, and forgave her for what she did, but she knew she was becoming something she didn't want to be, and went home to her mother, who seemed to know exactly what had happened just from the look on the young Griffon's face. "Rosie, you were born to hunt, to rule the sky with beak and claw. Griffons are predators, and very good at what they do... But you live among ponies, who are nearly the opposite. You must temper yourself, and put those instincts to good use, or you'll end up having to leave Equestria, maybe even flee it!"

Her daughter was close to tears at this point, but Ruby had a plan. She had been preparing for that time in Rosie's life for nearly a decade, and had already asked her uncle, the Earl of Red (a Canterlot unicorn noteworthy for leading the massive House of Red) to pull some strings among the Guards. They were rather apprehensive about having a Griffon in their midst, but she stuck to the training and discipline like glue, and once she cleared the difficult flying and stamina tests, the officers couldn't deny that she was going to be an exemplary Guard. In those days, there was only one Princess, Celestia, but the three branches still existed, and finally, after training hard for months and months, Rosewing Red was sworn in as a full member of the Air Guard. During the course of her career serving Celestia, she saw Princess Luna restored, protected the common ponies from chaos while Twilight Sparkle and the Elements of Harmony worked to defeat Discord, nearly lost an eye fighting off Changelings during her Captain's wedding, and, perhaps most important of all, was a founding member of Dusk Wing.

When Twilight became a Princess, Celestia and Luna allowed her to recruit a lot of interesting individuals to form her own Wing, Hoof and Horn, and Rosewing came highly recommended. Super-sharp eyes and nose, highly skilled with her claws, and a powerful flier, not to mention her dedication to Equestria itself, the Griffon seemed particularly well suited to the work Twilight's Guards would be doing. Indeed, endless bodyguard duty was getting a bit dull, despite the few major attacks that had recently occured, and Rosie gladly accepted. It was there that she gained the nickname "Clipper", as she was uniquely skilled at tracking down and catching rogue Pegasi, proverbially "clipping" their wings. The name was a bit dark, as clipped wings are a very morbid topic among fliers, but somehow, it stuck, until even her superiors were calling her Clipper! (though Twilight and her family stuck with Rosie, as did her closest friends outside of the Guard)

She rose through the ranks, proving her worth many times, and was the obvious choice to act as Twilight's representative to the Equestrian Explorer's League. Her mission: to protect the Explorers from all dangers, known and unknown, and to document every artifact and culture they discover.