I bought a WC yellowbelly this year just as you did and so far mine will take large black mice. Also I do not reccomend handling it for a while. Water it, clean its cage....otherwise give it some space and let it adjust. I took this approach with mine and it took it about six weeks to come around. It is still a shy snake though so its not one I get out just to hold. When I did offer it food I saved it for last so I could watch it's behavior. If I saw her retreat from the mouse I took the mouse out right away so as not to stress it out more than it already was. Hope this helps you wild caughts can be tough.