About 35 years ago, I was out in area near my hometown of Grenfell, SK, called the "Pipestone", hunting bush partridge (Ruffed Grouse). I heard a rather disturbing noise that I could only describe as what a duck would sound like if it was being tortured. I eventually found two porcupines up in some willow trees. They were adult. They were in separate trees, but only a couple of feet apart. I presumed they were "dating". I have never heard this sound since, nor have I run across anyone who has. Weird, to say the least.