At a year of age, a male or female Ball python can successfully take down a small rat. I didn't feed my girl small rats until about a few months ago (she's 1.6 y/o). Just last night, I fed her two small rats, and she took them down perfectly. My Kingsnake refused his small rat because he's in shed (otherwise he NEVER refuses meals) so I decided to feed the small rat to my female Ball python, and sure enough she takes it down with no problem (she hasn't refused food for me ever). I'm sure your yearling can take down a small rat.