Yes, it is Canon, in the show "donkey kong country" he has his hair on the top of his head shaved in one episode and he does infact have a wierd curl on his head
Fun Fact: The image of DK without hair is accurate. That tuft of hair on his head isn't a tuft of hair. It's actually a head deformality. In the DK show they shaved his head to reveal it and he lost all his powers after he got shaved.