I like the comments,
kinvesout - you make an important point. I think you are emphasising "realism" (ie, that the story elements should have a real grounding in reality) - which is one of my favourite literary topics.
However, the market says that for a lot of the readership, the elements of the bird culture are only meaningful if the culture itself would be meaningful to the plot. In other words, a lot of the time it won't matter to readers if the bird people communicate as like humans. However, if you can add such elements, without distracting from the plot, then you may create something quite memorable.
As an addendum to that - even different human cultures have very different ways of perceiving the simplest things. For example, here in the West we are very used to the idea that time "flows" forwards (and backwards in SF!). However, in Chinese thought, time moves up and down. A simple but important example of how thought can diverge across cultures on even the commonest principles of the human experience.