I've just become aware of rats running up the bird table to get
the bread. The rats seem to live under the shed.

I've put down poison bait on tobacco tin lids under the shed,
and this gets taken, but so do the tin lids!

The rats ignore the spring traps and the squirrel trap (big square
wire frame)

How do I get rid of them and also know that I've got rid of them?

They're only 10 foot from the kitchen door which I now keep
resolutely closed.