just take him out to where there are plenty vermin around and he will do the rest, hopefully, he will chase something if its alive most dogs would just sniff a dead rabbit also, just encourage him on the things he should be going after, BTW 1 year old is not to late to learn, but he wont learn sitting on mums knee, take him long walks where you would expect to see rats, along rivers canals, rubbish tips etc you may not see something the first few times but you will eventually.