The answer to 'mouse nests' is that mouse nests are a common sign of a mouse infestation in your home. Mice build nests to shelter themselves and their young, often using soft materials like shredded paper, fabric, or insulation. Symptoms of a mouse nest include droppings, gnaw marks, and sounds of scurrying in the walls or attic.
The best solution is to address the root cause by sealing up any entry points mice could use to get into your home, removing food sources, and setting traps or using humane deterrents. However, if the infestation is severe or you're uncomfortable dealing with it yourself, it's best to call a professional pest control technician who can properly identify and eliminate the problem.