For, well, ever, one of the main things that has been the separator between man and beast has been the ability to communicate in a complex manner, more than just "I'm here" and "this is mine." A recent study, however, may turn that on it's ear...or at least give it's nose a tweak. In it, starlings learned to differentiate between a regular birdsong "sentence" and one containing a clause or another sentence of warbling, according to a study in Thursday's journal Nature.
So, yeah, songbirds can be taught grammar. Which means that they are miles ahead of half the people in America.