Loftwing

A Loftwing is a species of bird featured in Skyward Sword. They are guardian birds used by the citizens of Skyloft to fly around the different regions and are used during the annual Wing Ceremony.

Overview
It is a custom in Skyloft for each person to have their own Loftwing, which is a symbol of the divine protection granted by the Goddess Hylia. A Loftwing and its rider have a special connection, as Skyloftians consider themselves to be one half of a pair until they are made whole by the Loftwings. When a Skyloftian is young, they meet their bird companion under the Statue of the Goddess. Having a Loftwing and being able to ride it separates the kids from the adults.

Loftwings cannot fly during the nighttime since they have a terrible night vision, and only those which have been specially trained can fly in the dark. They can also be taught a special move called the Spiral Charge, but since it is a stressful move for Loftwings to do, it is usually only taught to senior Knight Academy students.

The crest of the Goddess Hylia and later the crest of the Royal Family is that of either a Loftwing alone or with the Triforce above its head, a symbol that appears throughout the land of Hyrule in many games within The Legend of Zelda series.

Crimson Loftwing
Link's Loftwing is a special, rare breed which causes him to stand out among the rest of the citizens of Skyloft. It is considered a rare breed which had been thought to have disappeared.

Evolution
The Loftwings may be the ancestors of the Oocca seen in Twilight Princess. Skyloft has been theorized by some to have become the City in the Sky, and the Loftwings are implied to have stayed in Skyloft even after the Hylians returned to the Surface, so it would be logical for them to have gradually evolved over the centuries. Moreover, the Loftwings do display a great deal of intelligence, as they develop strong emotional attachments with their riders, seem to understand the Hylian language, and are able to distinguish the whistles of their riders from those of other Skyloftians, and Link and Zelda's Loftwings even display keen perception, as they leave their riders behind when they decide to live on the Surface, despite being given no command to do so. If the Loftwings did indeed become the Oocca, it is possible that their Sky Writing (and perhaps even their spoken language) could simply be Skyloftian Hylian, which normal Hylians had long since abandoned and forgotten. Shad's account that the Oocca created the Hylians would potentially contradict this idea, but indeed could itself simply be a misinterpretation of history.

Trivia

 * The Loftwings were modeled after the Shoebill, a species of bird native to tropical east Africa. The idea for their curled tails came from one of the designers' pet shiba.
 * As all shields in Skyward Sword have a footprint or depiction of the Loftwing on them, it appears the red bird on the Hylian Shield is meant to represent a Crimson Loftwing, a rare breed of the species.
 * In the opening cinematic, one can see Eagus flying a Loftwing for a brief second. Looking close reveals that this Loftwing is a lower polygon model; it looks different and slightly blockier than the other ones. This is likely a mistake on the part of the game developers. An unused crimson version can be found in the game data.
 * Many Loftwings bear characteristics similar to their owners. Strich's Loftwing has a similar bowl haircut and belt.  Cawlin's Loftwing has a similar haircut and belt.  Groose's Loftwing has a similar pompadour haircut, and belt matching Groose's necklace.  Zelda's Loftwing has a similar 'golden circles' belt.  Orielle's Loftwing has hair also in braids.
 * Despite the importance placed on loftwings in Skyloft's culture, no bird is ever given its own name, or at least is never outright stated to have one.