I only guess so that a cat which devours a poison-terminated mouse might get poisoned in result.
Very likely. Modern rat poisons are anti-coagulants and as such the rats will bleed to death. It is a slow death too. The poison can stay in the body for months and will get higher up the food chain as rat predators such as foxes and birds etc will get secondary poisoning from ingestion.
I didn't want to use poison but the final straw was finding one in the kitchen. Came back from serving dinner and it was there looking at me before it bolted and ran.
No success after two days. Yet.
Mine has been months now. To start with rats are neophobic. They don't like new things and your cage trap is the equivalent of a big red flag for the rat. Secondly, they are very good at detecting human scent. You should have used gloves when setting the cage up, preferably rubbed in soil too.
suddenly realised rodents don`t need compost refuse cos they can easily feed on nuts
They might just prefer your compost. There is no food whatsoever in my garden but I still had a problem. I learned years ago that I couldn't have bird feeders and now the pond has gone so they don't have a water supply. It got so bad at one point that what I thought were frolicking squirrels in my flower beds turned out to be rats :(
Had to remove all plant pots as they were using them to hide behind in their exploration of the garden. Now my garden just looks dead but the sewer repairs and pond removal seems to have done the trick.
Best of luck!