So, I'm thinking about a possible project wherein I draw all (or most) of the monsters out of the MM or the Fiend Folio, and so looking through those tomes to decide on which would be more interesting. Flipping through the Fiend Folio, I realise something that's never hit home to me before: there are a ludicrous number of bird-monsters in this book, most of which are severely lacking in the 'cool enough to use in my game' category.
But I have the solution. The aarakocra, dire corby, kenku, and achaierai (the worst name ever) are all native to some far-flung, half-legendary kingdom aking to Prester John's, only ruled by birds. Aaracokra are, instead of being bland noble-looking eaglemen, like peafowl with flashy colourful males and drab females of shrewd business acumen. Dire corbies, which look like ostriches or cassowaries with weird arms instead of wings are the enforcers and muscle of the bird-kingdoms, achaierai (still almost too stupid to type) are like elephants, with howdahs on their backs stuffed with lavishly dressed aarakocra maharajahs and their avian harems. Kenku are sneaky corvid nuisances (and actually have a place in ordinary places in the game). In the Avian Kingdoms they're more like working-class Dickensian crowmen, with braces, grubby bowlers, cockney accents, and gin habits.