finches
i have a pair of 6foot olives that have been known to go off the rats every now and then for no apparent reason. what i do is keep a couple of finches in the freezer with my food, and if i need them i defrost one and rub it all over the rats prior to feeding - nine out of ten times they will go straight for the rat and that is the end of it!
the first time i placed the finch and rat together and they knocked past the finch and ate the rat.
apparently birds are more likely to carry worms or parasites so if you have to do this too often keep an eye on your snakes and consider worming next time you are feeding them.
anyway, this is what works for me, hope it helps you out mate.
bombie