Ryle Aislyle the Alicanto

Antu is an Alicanto, a Chilean mythological bird known for eating metal and their feathers taking on the characteristics of whatever metal they've been eating. Most recently he's been eating silver, so his hair and eyes have taken that color. He also glows in the dark.

Literal birdbrain.

Antu is a Spirit! Which in his world are mythological beings who form pacts with human beings. In exchange for being able to exist corporeally in the real world, the human being is able to tap into the spirit's magical powers. As such, he would register as a magic beast to those attuned to that kind of thing.