Scratching or Scurrying Sounds in the Attic at Night — San Francisco, California

Persistent scratching, scurrying, or thumping noises from the attic after dark are a strong indication that wildlife or rodents have found a way inside. Squirrels, raccoons, rats, mice, and bats are the most common attic invaders — each leaving a distinct acoustic signature ranging from rapid scampering to heavy thumping. These animals enter through gaps at roof-soffit junctions, damaged fascia boards, uncapped plumbing vents, or deteriorated gable vents, and once inside, they nest, gnaw on wiring and structural wood, contaminate insulation with droppings and urine, and can introduce parasites such as fleas and ticks. Chewed electrical wiring is a significant fire hazard, and accumulated droppings can harbor histoplasmosis spores. A pest control technician can identify the species through droppings, tracks, and entry-point analysis, humanely trap or exclude the animals, seal all entry points with galvanized steel mesh or metal flashing, clean and decontaminate the affected insulation, and install one-way exclusion devices where appropriate.