They were a very religious people, focused upon their leaving to the afterlife. If their sins were as light as a feather, they would go to heaven. Else they would be eaten and their soul stuff would eventually be recycled into a new spirit. If you went to heaven, but still had a mission upon the Earth, or your sins were equal to the feather, you would be reincarnated. Unfinished business is the only reason for ghosts, thus helping a ghost was a high honor.
They associated magical spirits/ gods with birds. It is difficult to determine if this was metaphorical or actual. Their gods are shows as fully human, human with a bird head, or as large birds. In fact, the names for their Gods have become the "common name" for most birds.
Given their beliefs, bird motiffs are everywhere among Aviontix artifacts and ruins. If you find a really old magic item, it will have a bird motiff on it… given that it came from Aviontix. While Aviontix was a very magical place, very few of their items have survivied the "sands of time". Many have been broken, but most are lost or unable to be recharged.
In addition, it seems that Rocs (huge birds) and Pheonix\\\‘s/ Firebirds were either created by or bred to their present form, by the Aviontix.
Diety List Example
Sunbird: The Sun and fire were the manifestation of the divine upon the material world.
Eagle: Force of Nature- God of Sky and Weather
Hawk: Warrior, keeper of Order
Falcon: A noble diety, patron of that class. Seems to be male or female at whim.
Dove: Goddess of Peace and Mercy
Swan: Goddess of Beauty and Art
Gull: Madcap god of the Sea and Water.
Owls: Watchman of Death/ Chaos/ Darkness. A wise diety.
Raven: God of Death. Ravens took souls and other things.
The Cat: This creature would have a unique place in the pantheon of Aviontix. There would be a cat goddess, and she would be both alligned with but acting against the Raven. Perhaps Cats are seen as a way to prevent excesses via magic or spirits.