House mice Vs wood mice
The wood mouse
The most common urban mammal is probably the wood mouse. They are everywhere, but usually nocturnal so not seen by us. The most common way for most urban dwellers to come across a wood mouse is when their cats bring them into the house. The good news is that wood mice prefer to live outdoors. The most damage they’ll do is if they find your veggie patch as they are very partial to veg. They will happily munch their way through your green beans, carrots etc. What they won’t do is move into your house. In fact they would probably die of starvation indoors.
The best thing to do with a wood mouse is to put it back outside. At most, wood mice may take up residence in your garden shed, but only because it provides a bit of warmth and protection and easy access to the outdoors where they forage.
The house mouse
House mice are a different problem altogether. They have evolved to live with humans. They can’t survive outside our homes so if you release one outside it will probably die, move back in with you, or take up residence in your neighbour’s house. The first hint you’ll have of a house mouse invasion is from small black droppings and a horrible smell of mouse urine. The only safe way to get rid of house mice is to get in an exterminator. Don’t just put down poison, as poisoned mice might land up in the food chain and kill an animal you didn’t want to harm. This is especially true for poisons the mouse may have gained an immunity to. In London there are super mice who can eat poison and not die. If they are caught and eaten, their predator could die. Exterminators usually (or should) put down their bait inside a box, the mouse goes in, dies in the box and then the body can be safely disposed of.
Telling the two mice apart
It’s relatively easy to tell the two animals apart because a wood mouse is a rather attractive chestnut colour on its back and white underneath (juveniles - i.e mice that have just left the nest might be a bit greyer). The wood mouse has surprisingly long back legs that makes it look a bit like a miniature kangaroo. Wood mouse urine has no perceptible smell to us.
A house mouse is a uniform grey colour top and bottom and had short back legs and as mentioned before, strong smelling urine.