lovezebs Babs
There's really never been any issue of compatibility. I don't do anything special. While most of the larger birds were introduced as babies to eachother and the smaller birds, two of the budgies were adults and several years old when they were brought in and they're still peaceful as could be. I put it down to their simply being of good temperament, and having only a single gender is surely helpful.
I think that given enough space any non-predatory birds can get along - they do in the wild, after all. I'm sure aggressive individuals exist but I've yet to have observe any of my larger birds try to cause any trouble with the smaller ones. For the most part they ignore them. Sparky the dove sometimes courts the finches and smaller doves and chases them a bit when he wants to throw his weight around, but they know he's all bluff and just casually move out of his way. The cockatiels and the budgerigars have a definite flock bond and they preferentially share a cage, the tiels freak out if I cage them separately. The grey tiel Freddy and green budgie Sam have a particularly strong bond, and Freddy allows Sam to preen him and regurgitate for him, which is interesting since Freddy is also closely bonded to his young female companion, Todd - and then Todd has a close friend on the side too in Sydney, the blue budgie, who loves to snuggle up to her in the evenings and groom her crest feathers. Sydney is, however, most especially bonded to his bud Arthur, the pied budgie, and those two have not been apart for more than a few seconds in a year and a half, since they met. They're the only parakeets I've seen who sleep side-by-side touching every night (normally budgies like space.)
The other most noticeable cross-species bond is between Snickers the zebra and Claire the albino society, who are attached at the hip all the time. Claire has bad eyesight and is a slow flyer as a result, and the other four socies often fly too fast for her to keep up. Snickers always stays beside her and keeps her company and preens her and the two have become fast friends.
Occasionally, Sebastian the canary will preen the two young society brothers - they're the only ones who grew up with him around and don't mind. That's pretty cute, too. When Sebastian sings the two will hop right behind him and gather on either side, heads cocked, listening to his every note. It's be lovely if they tried to sing his tune as adults but so far, their songs are developing to be like their father's.