The answer to 'why is my mouse nests' is that mice build nests to create a safe, warm, and comfortable living space for themselves and their young. Mice are prolific breeders and will construct nests out of a variety of materials like shredded paper, fabrics, insulation, and other soft, pliable items they can find around your home.
Seeing mouse nests is a clear sign of an active mouse infestation. Mice are attracted to homes that provide food, water, and shelter, and they will quickly establish nests in quiet, hidden areas like attics, walls, basements, and crawl spaces. If you find mouse nests, it's important to take action quickly to eliminate the infestation before it gets worse.