[quote] If you only put bread on the bird table and not the ground, try using a
squirrel baffle (large plastic dome used umbrella-like on the leg of the
bird table) to stop the rats reaching the table surface. [quote]


I have watched a rat let itself down onto a plastic dome, curl the end of its tail around the support and then it was able to reach the food. They are very intelligent beasties.

Poisoned bait in a tube was the only effective deterrent [apart from a good active terrier!].