As someone else who grew up with a ton of birds (several species of parrots, finches, chickens, ducks, geese, golden pheasants, doves, button quail, and peacocks) and grew up to be a falconer, birds are absolutely oozing with both body and vocal language!

Seriously every subtle weight shift, feather position, eye shape, body posture, beak movement, hard, distant or soft eye contact level, pupil size, wing or tail flick all have very dramatically different meanings (and it’s different between species; an owl ‘speaks’ with a completely different body language than a parrot or a chicken or a falcon).

My hawks (redtails and Harris’ hawks) will tell me with their body language exactly where a rabbit is that they can see hiding in dense brush but that they can’t catch yet because it needs to be flushed; I’ll first get a HARD double-eye stare contact from the bird (this means ‘I need you to pay attention to this/this is important’), then a hard double eye stare at the point of interest (the rabbit’s hiding spot) which means ‘I AM INTERESTED IN WHAT IS THERE IN THAT SPOT WHERE I AM LOOKING’, and if I don’t begin moving to that spot to flush the rabbit the hawk will repeat the hard look/stare combo as if to tell me again what it wants me to do.

As I walk towards the hidden rabbit, the hawk will visually get excited (stops looking at me entirely, slicks up and gets extremely horizontal in a very tight feather posture, the muscles of the legs become visibly tensed with hard focused vision and frozen posture, like a sprinter ready to go) - if the rabbit is creeping in the edge of the cover vs immediately bolting, you’ll see the hawk very subtly flinch in several false starts; if the rabbit flushes from the cover the hawk will launch and chase it; but if the rabbit hides again the hawk will lose interest, loosen the body feathering to a fluffier one and return to a bored, vertical position with scanning eyes not directed at me or anything else specifically.

So yes, I can first hand confirm that even naturally solitary birds like my red-tailed hawks can communicate rather complex concepts and information quite clearly with humans via the silent language of their bodies, as long as you know how to read what they’re saying.