You will have rats whether they're fed or not - they're everywhere. Far more important is helping animals such as the hedgehog - which is in sharp decline (in the 1950's there were 30 million in the UK; today there are less than 1 million!) At the moment, they will be desperately searching for food to put on weight to prepare for hibernation and need to be around 650g to safely go into hibernation and come out of it (many die and never do, because they are too light). Your neighbour is doing a fantastic thing (more of us need to do it) and probably getting a lot of pleasure out of it too, so I would say nothing. (And if anyone wants to learn how to help hedgehogs in your garden, you cold start by creating a Hedgehog Highway - see hedgehogstreet.org for advice. One hedgehog needs around 30 gardens to pass through. They need a constant source of water. Feeding is great - NOT bread and milk! Oh yes and never EVER use blue slug pellets which kill them). Good luck in your new home.