The bird makes a call that sounds like the word "dee", over and over. Just as someone who runs is a runner, a bird that's dees, is a dee-r, so it's not deer in the sense of the animal the way you may think. At least that's what I've been told. The "kill" part is a bit strange, but I'm assuming it comes from the fact that this bird will feign a broken wing to distract a predator away from their nest. All in all, I'm really not sure on the origin of the name, but that's what I've learned in my last 3 years of actively being a part of the birding community.
