"How Avians Kiss" Passionately. Whenever my Avian ended up in such a romantic situation, I always had them do a forehead nuzzle/necking type thing. however I can't speak on behalf of sapient bird people so I can't vouch for the accuracy of that.
Personally agree - forehead touching and even a bit of preening are like giving someone a kiss on the cheek, and rubbing beaks together to show deep affection.
Those two are preening for hygiene reasons and they are making friends, like you might kiss a very good friend on the cheek.
I choked on my rich tea biscuits when I saw this... Then laughed out loud... Then started coughing... Then congratulated you. Nobody fucking makes me laugh out loud like YOU did with this, good sir. I SALUTE THEE!!!!
I like the four image that on doc's original post. It is loving and a surprise. Everything a kiss should be.