Oddly, this topic has come up in various parts of my life recently.. Michael Morpurgo's book 'A Song of Gladness' was inspired by his communication with a bird.. the post script is fascinating.
I have had a few bird encounters too weird to describe on Mumsnet as the logic people will tell me it is a coincidence. I was with someone, gently listening to pleasant evening birdsong through the open window, thinking about something I was reluctant to say as it would break the mood, a crow squawked loudly, so I took that as a cue to speak my thoughts and when I had finished, the gentle soothing bird song returned.
And a friend of mine was talking about a course she followed about animals communicate with us all the time - but we are too caught up in our own world to notice or too constrained by our own thinking and beliefs to allow ourselves to understand ... I must ask her more about it!
I also think there is a reason why there are so many stories written about communication between humans and animals.... I don't think it is total fantasy.
I am also reading a fascinating book about language and it's power and how the resonance of different languages can make different patterns and chanting or singing in different languages can have different impacts on our states of consciousness... I could go on.. the book is Thirty Two Words for Field...