Are Jack Russell x rat terrier cross good for guarding chickens?

Umm... depending on how you train your dog has a BIG impact on weather it can guard chickens or not. We taught mine to hunt or kill small animals such as chickens so my dog couldn't possible guard chicken without eating them. But if you train your dog to guard chickens he could guard them but there is a small possibility that it may eat the chickens since that is what it was initially bred for.