I can do pretty good impressions of birds. Do you know about that? 
Can you do both bird calls and bird songs?
Yes I think I do both. What is the difference though exactly?
In birding, songs are distinguished by function from calls.
That's pretty interesting. What kind of functions are we talking here?
The difference between songs and calls is a matter of complexity, length and context.
What birds have really complex songs and calls?
Wrens are inconspicuous, except for their loud songs.
What kind of bird is a wren? Where does it live?
Eurasian wren are found in Eurasia and Africa.