I wonder what W&S would do if they caught one.
I can tell you precisely what they would do, from past history. They would tear it apart and eat it.
So how do you work with W&S not to chase the death wish fluffies? Maybe it's something I could do with Carbon to help with his ball addiction. Plus any sort of 'running' (or my version of it) has to be good for me.
I have a few tactics, but I wouldn't use the same method for ball training, because that's SO much easier to set up. I don't know where the rabbits are going to be, so I have absolutely no control of them popping out or not, so I have to be reactive rather than proactive. With balls, I'd just work on a structured program of "orient to me" when you see a ball being thrown.
With the bunnies, what has worked in the past is carrying a Chuckit ball with me. If I can, interrupt the chase before it starts with a loud "YES!" - this has obviously been conditioned as "turn to me for reinforcement" for a million other things, so it can stop the dog in his tracks just from the learning history. Even if it's a flicker of an ear, I can then chuck the ball in the other direction so it bounces quite close, and that noise is normally enough to break the dog off to chase the ball.
Rinse and repeat. A lot.
If I don't get the "yes" in in time, I just wait for the dog to give up on it, and the second they turn to me (or at least, the second I see them again, if they've dived into the woods), I give my "YES" and throw the ball.
I also do the mark and ball for anything else unexpected that makes them look - a bird flapping in the trees, a lizard running, a farmer on his tractor etc.
So they start pairing "something catching my attention" with looking back to me. It's normally a remarkably quick process for them to start actually looking to me when these things happen.
Also, sometimes if it's safe (for the bunnies), I actually release them to "chase" after the rabbit has made its getaway. There are a few places that are perfect for this, where I know there are often a few of them at the end of an open field. They see the rabbits, look at me, I say "YES!", which scares the rabbits back down their holes, and then I release with a "go play!" to go belting down the field. There is no chance of them catching the rabbits (which all disappear in the blink of an eye), but they get the reinforcement of hunting the fresh scent. If you can reinforce NOT engaging with the "thing" by allowing them to engage with the "thing", it can be very powerful indeed.
When I talk about doing this, people
always say "but my dog would never choose a ball over a rabbit". This makes me laugh because - uh - neither would mine. Yes, they love balls, but compare that to the erratic chase of a live critter, with tasty warm blood in its veins? Umm, nope, if it was a real decision the dog was making, the rabbit would win every time. But that's the beauty of training and reinforcement histories. There is no point where the dog is weighing up which is better.