The long-tailed field mouse or wood mouse, Apodemus sylvaticus, is found over nearly the whole of the British Isles. It is a variable species, and scientists have divided it into a number of sub-species, of which the type is very common in the Box Hill region of Surrey where I live. Another mouse which some specialists regard as a sub-species and which is known as the yellow-necked field mouse, A. flavicollis, is said to occur in the district though I have never seen one. It would be interesting to know more about the distribution of these mice and amateur naturalists could make useful observations on their ecology.