The population of long-tailed field mice can explode quickly, but they are an important source of food for barn owls
All over my lawn, I have holes that are 1-2 inches across but appear to lead into tunnels. What is making these holes? They are not big enough for rats or rabbits.
I went to see my mum and she took me through a lengthy tour of her field and all the holes it contains. Rabbit holes, mole holes, bee holes, mice holes – it was quite the tour, because every hole needed to be examined carefully. One of the holes was made by a long-tailed field mouse (aka wood mouse) and it sounds very similar to yours – it’s about an inch across and leads to a burrow.
Their population can explode quickly if they like the conditions, and my mum tells me they can appear all over the place. Then at some critical mass it all gets too much and they move off to find new territory – overnight they seem to disappear.
Source: Guardian Environment