Just been reading this thread since after nearly 5 years here we have started to see our first wood mouse in the house. Cheeky little thing is getting everywhere too! I decided to find a solution after I was relaxing on the couch and the blighter came out from under the other into the middle of the room to take a good look at me! After 20 seconds it ran back under the couch. A minute later after I realised it was gone and not coming back. It came out into the middle of the room and took another 20 seconds look at me!! I then went looking for it but could not find it. it has however been out overnight since then.
So we have peppermint balls and humane mouse traps on order. I looked around online for advice and an prominent wildlife charity had a lot of advice on dealing with mouse pest problems. They said a humane trap is best and release somewhere similar but at least 2 miles away. The range of advice on distance was 2km to 5 miles!! Apparently they have a good sense of direction and often return to where they know.
Anyway, the advice mentioned above that was linked to from the RSPCA I do question the source a bit. It is not the RSPCA. The other point is that some of its information is actually wrong or potentially wrong. In the UK the wood mouse is more likely to be the species in your house in most places across the country. However it is very hard to identify a small rodent especially when they are pretty fast blighters. I only IDed my interloper because we were staring right at each other for two sets of twenty seconds. I got a good look at the colouring (complete with darker flecks), bigger rear legs and a few other features such as the motion of it. I bet it is rare that anyone gets a good look at them other than in a trap, certainly not have a decent look at them to see their motion / habits.
I have looked around the house and struggle to see any way in other than through the air bricks. We cannot block them up, unless wire wool in them will do it without stopping what little airflow the bricks already get. We have so many nooks and crannies they can hide in and will never stop them. So we are using peppermint balls to repel them if that works at all. Also we will place humane traps around the areas they have been known to go most. Once caught they are going to a nature reserve that actually has similar habitat to our area. That is the best fighting chance we can give them. However it must be pointed out that in the wild many mouse species rarely live longer than a year and many less than 6 months is known too. Ours could have been here 6 months already so IF they die where we release that at least is natural and within the bounds of normal wild lifetimes.
What I wonder is how long they could have been here? We think it is only the last 6 months, when we look back at things, and they have only been active when we went on holiday and of August. That was when we found things chewed into so that is the only real timescale we know for certain. We have seen mice living in the little garden by the footpath about 250m up the road (maintained by the parish council). We have seen a mouse pop out into the footpath, look at us and the dog then dart back into the undergrowth. That was last year. We also saw a vole and shrew in the garden but no mice there. My partner has seen some in the drystone retaining wall at the boundary of the patio outside the back door. I suspect we had a population develop over a number of years and is big right now so the overflow has moved into our house. I suspect it is a the natural ebb and flow of populations in the wild and in a few years time they will get predated back down to lower levels and the ones in our house will end up not being there, or new ones not come in to replace the older, dead or caught ones inside the house.
The advice to keep food away from them, clean work surfaces, cover bins, etc. is good general advice but not a good one. They can chew through plastic and wood to get to food so unles you have a load of metal boxes I doubt you will stop a determined mouse by trying to stop them getting food inside. It could help but not solve the issue. IMHO it is about keeping numbers down and stopping them from being so active in places we are active in.