Scratching, chirping, or fluttering noises at dawn and dusk; staining or dark smudges around roof vents, eaves, or chimneys from oil and droppings; accumulations of guano (small, crumbly droppings) beneath roosting sites that may smell ammonia; nests or nesting materials (twigs, feathers, insulation) in attics, vents, or wall cavities; visible birds roosting on ledges, rafters, or in vents and bats seen exiting in swarms at dusk or returning at dawn; entry points such as gaps in soffits, torn screens, loose vents, or holes in roofing and siding; and increased insect activity near exterior lights (attracting bats) or pest birds leaving feathers and seed husks around eaves and balconies.

Chewed wiring, torn insulation, frayed ductwork, and small holes gnawed into wood or plastic are common signs of rodent activity, while squirrel damage often includes larger, more irregular chew marks on eaves, fascia boards, attic vents, and roof shingles as well as shredded insulation and conveyor-like pathways in attics or crawlspaces; snakes leave subtler evidence such as shed skins, shed skin fragments near foundations or under debris, droppings that are dark with a lighter tip, disturbed soil or rodent carcasses (since snakes often feed on rodents), and entry gaps under doors, vents, or foundation cracks large enough for their slender bodies—any of these signs, especially when combined with tracks, odors, or repeated noises, indicate an active pest problem that needs inspection and exclusion.