I was Googling for an essay I'm planning to write on reduplication in Siouan languages the other day, so I typed in "Crow language". I was somewhat surprised to come across an article on the vocalizations of the American crow as my second hit, so I thought I'd share it. Apparently, 27 different vocalizations have been noted in the scientific literature (with names like "scolding call", "distress call", "courtship vocalizations", and "pre-mortality call"), and many remain undeciphered, so to speak. It would certainly be interesting to get a really good idea of the communication system of an animal as intelligent as the crow; bees are all very well, but perhaps a little too alien to compare sensibly with human language.
I never did find anything very helpful online on the Crow language, but John Boyle's Siouan Languages Bibliography will certainly come in handy, and this sketch of Omaha-Ponca seems good, though of limited use for what I'm researching.