What if the birrins' home system has another planet with sentient life on it as well? I just love that kind of idea. It would also make it easier on the birrin when meeting humans; they would already know that there are "aliens" out there.
I've never really taken the time to comment before, despite quite thoroughly browsing your work, but I love your non-humanoid take on alien life. It's such a shame that humanoid, bipedal lifeforms are the easiest to budget for in modern scifi, if only because it's actually only one of a myriad of shapes intelligent life could possibly take.