Depends on what kind of mouse though. Woodmice are normally tolerated as they're quite cute and live mostly outdoors. But infestations of house mice are something that local authorities/pest control are regularly called out to deal with in the UK. If they can get in and get a toe-hold, especially where they've found a good food source, then they can run riot.
INDEX CONTOUR LINE A bolder/wider brown line that has the elevation value marked at various intervals as a part of the line. These contours typically occur every fifth line. Use an index contour near the point for which you are trying to find the elevation as a first step to determining the elevation of that point. Example of an index contour. This is the basic symbol that you will use to determine the elevation of a feature or location. It is a brown line on a topographic map and represents a line of equal elevation. All locations that a contour lines crosses have the same elevation at that point.
The contour interval of a topographic map is the difference in elevation between successive contour lines. Contour or isarithmic maps can be used to show a variety of phenomena such as precipitation, temperature, atmospheric pressure, or solar radiation. Data used in isarithmic maps are not confined to predefined political or geographic boundaries. Rather, the data's parameters are as varied as its environment. More generally, a contour line for a function of two variables is a curve connecting points where the function has a same particular value.