I was in a similar situation and here is what I did and it worked. I took a wild bird nest with hatchling chicks and placed it into the cage. The snake ate within a day. I then would place mouse and rat pups into the nest. The snake ate them. I have also heard they will not refuse snakes of other species. I have not tried that but scenting with other snakes might work if that is the case.
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"Life without risk is to merely exist."