Cannonly, Astrians are small feral creatures with the intelligence of a very smart bird like a Magpie or other corvids. They are able to recognize others and themselves in a mirror level of intelligence and show intermediate problem solving skills. They are protectors, guardians, although they might not understand that exactly or reasoning behind it, they do understand to protect and will willingly approach people if they feel they are too close to the area they are protecting. 
Two popular theories surrounding them are;
1. Being a modern evolution of Microraptors or Archaeopteryx or
2. Being decedents of spiritual guardians of the area. 
Both of these are considered cannon.

For Anthro depictions, my own cannon sees them in either medieval times with knights and magic or on the opposite end, spacefarers, harnessing the stars as their own. Both of these are my own personal cannons but you're free to see it as the Anthro cannon for the species.

Anything outside of their feral depictions however, or outside of my own anthro cannon is seen as Non-Cannon for the species and your characters. 
It doesn't mean it's not allowed! But it cannot be a cannon history for your Astrian. Non-Cannon, you are free to depict them however you wish and I'm excited to see the stories you come up with for yours.