1. [Young]
A Glowl nestling isn't afraid of the dark: it glows! The tail feathers are so intensely pigmented they continue to be luminous even when shed. Glowl plumes are highly prized as torches, and since these creatures molt only once in a lifetime, very rare.
2: [Adult]
Fully-fledged Glowls are an imposing sight, with a song that carries vast distances. There are many legends regarding the marvelous powers of a Glowl pinion, but they are never shed, and no one has ever attempted to pluck one.
3: [Prismatic]
This Glowl returned from the Prism Gate forever changed! Its lighter-than-air feathers and bright-burning tails have been altered at the molecular level to become stalwart scales of resplendent color and... no tail at all! Extraordinary!