Temperamental Skyclaw

Slyverns are rarely comfortable acting as mounts. Only those willing to feed their gluttonous appetites and keep a careful eye on them should attempt to ride.

Riding Requirements:

This mount is available to all eligible characters on your account.
Level 10
Apprentice Riding (ground)
Expert Riding (flying)

Source:

Zon'Wogi in Three-Falls Lookout, The Azure Span.

Notes:

As Zon'Wogi at Three-Falls Lookout in The Azure Span explains, he'll give you this mount if you bring him 20 of each of the "treats from da gnoll tribes that not be fallen to decay". The three food items are:

Tuskarr Jerky: drops from gnolls around Darktooth Pond (approximately 35.0, 45.0). Possibly also some other camps.
Flash Frozen Meat: drops from Snowhide Camp gnolls (around 59.0, 44.0). It's possible it only drops after completing some of the area's storyline, beginning with Riders in the Snow and culminating in True Survivors, but we've also had reports that this isn't necessary.
Gnolan's House Special: drops from gnolls inside, or just outside at the entrance of, a gnoll "inn" in a hollow tree around 23.0, 43.3 at Brackenhide Waterhole (south of the pond), but seemingly not the rest of Waterhole area.