I can imagine real raptors making sounds like these. After all, they can't talk using words like people can, so they would probably have used a number of different sounds to communicate with their pack-mates. With some of the sounds they make in the movie, it's a bit difficult to figure out what the raptors are saying, but with others it's damn obvious. Like when Hoskins is in the raptor's enclosure and he touches Delta. She lets out an incredible growl which basically says "Stay away! I don't like you and, given the opportunity, I'll rip your head off."
The traditional greeting of Dinotopia: "Breathe Deep, Seek Peace"