The fox squirrel (Sciurus niger) is the largest tree squirrel in North America and a common sight across Montana's urban and suburban neighborhoods. With their rusty-orange undersides and large, bushy tails, they are a familiar and generally welcome presence — until they decide that your attic, soffit, or wall cavity is a better home than the nearest oak tree.
Fox squirrels are opportunistic nesters and powerful chewers. Their incisors never stop growing, which means they must constantly gnaw — and wood, plastic, aluminum, and even electrical wiring are all fair game. A squirrel that gains access to your attic will chew insulation, gnaw on wiring (a genuine fire hazard), shred stored materials for nesting, and create entry holes that worsen with time and invite additional animals.
In Montana, fox squirrels are most likely to attempt entry in late fall as they seek warm overwintering sites, and in late winter or early spring when females search for protected denning sites to raise their young. Once inside, they are territorial and persistent — and their droppings and urine cause lasting odor and potential health concerns.
Size
18–28 inches including tail; up to 2.2 lbs
Color
Rusty-orange belly; gray-brown back
Active Season
Year-round; entry attempts peak fall and early spring
Risk Level
Medium–High (fire hazard from wire chewing; structural damage)
Habitat
Tree canopy; attics, soffits, wall voids
Litters
2 per year; 2–4 young per litter
SIGNS OF INFESTATION
Signs Fox Squirrels Have Entered Your Home
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Scratching or rolling sounds in the attic — Particularly during early morning and late afternoon when squirrels are most active.
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Chewed entry holes — Ragged, gnawed openings in fascia boards, soffit panels, roof vents, or where the roofline meets the exterior wall.
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Droppings in the attic — Scattered dark pellets approximately ½ inch long, often concentrated near the entry point or nesting area.
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Nesting material — Piles of shredded insulation, leaves, twigs, or stored materials gathered into a nest mass.
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Chewed wiring or pipes — Gnaw marks on electrical conduit, PVC pipes, or insulated wiring in the attic or crawl space.
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Squirrels seen on the roofline — Consistent presence of squirrels on your roof, particularly near soffit corners or ridge caps.
HEALTH RISKS
Fox squirrels can carry fleas (which may carry murine typhus), leptospirosis, and salmonella. Their droppings and urine in attic spaces can become airborne particulates when disturbed during cleanup, posing a respiratory concern. Squirrel activity in attic insulation can also facilitate mold growth due to moisture introduction. Any attic cleanup following a squirrel infestation should be performed with appropriate respiratory protection.
PROPERTY DAMAGE
Chewed electrical wiring is the most serious risk — squirrel-caused wire damage is a documented cause of house fires. Beyond that, gnawed entry holes worsen with each entry and exit, allowing water intrusion and inviting additional wildlife. Damaged and urine-soaked insulation loses its thermal value and must be replaced. Attic structural members, stored items, and HVAC ducts are all subject to damage from an active squirrel occupant.
