Red Squirrel
Tamiasciurus hudsonicus
Red squirrels are an occasional but persistent commercial pest, particularly in office buildings and commercial facilities situated adjacent to wooded or heavily treed areas.
Their aggressive territorial behaviour and year-round activity (unlike the grey squirrel, which may reduce activity in severe cold) means that commercial facilities face a longer potential management window.
The primary commercial impact is structural damage from gnawing and nesting in roof spaces and wall voids, contamination of attic insulation with urine and faeces, and the fire risk associated with chewed electrical wiring. Commercial buildings with extensive flat roof areas, HVAC penetrations, and aging fascia and soffit assemblies are most vulnerable.
Habitat
Commercial facilities most vulnerable to red squirrel entry are those with: adjacent wooded or heavily treed areas providing food and dispersal habitat, aging or deferred-maintenance rooflines with gaps and deteriorated fascia, HVAC equipment penetrations on the roof that are not fully sealed, and large flat roof areas with parapet walls where squirrels can access the building envelope.
Green infrastructure such as green roofs with planting zones can attract and sustain red squirrel populations in close proximity to the building’s entry points.
Active Areas
Windsor
Tecumseh
LaSalle
Amherstburg
Lakeshore
Wooded corridors and mature mixed-wood areas increase local prevalence.
Essex
Rural-urban fringe areas with coniferous habitat.
Kingsville
Leamington
Chatham-Kent
Low prevalence. Found in wooded areas of Chatham-Kent but rarely causes structural pest problems.
St. Thomas
Low prevalence. Occasional attic entries from wooded residential areas.
Seasonality
Commercial pest management programmes should address red squirrel exclusion before the autumn entry window (August–September inspection and sealing) and conduct a follow-up inspection in spring (March–April) when dispersing juveniles may find and use any gaps missed during the autumn programme.
Year-round monitoring of roof space access points is advisable for commercial facilities in high-risk wooded locations.
Spring
Summer
Autumn
Winter
Appearance
For commercial wildlife identification, the red squirrel’s small size and reddish colouration immediately distinguish it from the much larger eastern grey squirrel.
Evidence in commercial buildings — food caches in attic insulation (primarily seeds and conifer cones), chattering alarm calls heard from the roof or wall voids, and small, clean entry holes in fascia and soffit material — are the most useful field identification indicators.
Confirmed red squirrel activity in a commercial building should be documented and a professional wildlife removal assessment initiated promptly.
- Rusty reddish-brown back and tail with white to cream underside and a distinct black lateral stripe in summer plumage
- Winter plumage has less distinct side stripe and may show greyish tones
- Ear tufts in winter — small but distinguishable projections from the ear tips
- Much smaller than the eastern grey squirrel and considerably more aggressive and territorial
- Distinctive loud, rapid chattering-scolding alarm call — one of the most vocal of all Ontario squirrels
- Active year-round even in cold weather — does not hibernate, though activity may be reduced in extreme cold
Behaviour
Red squirrel behaviour in commercial buildings mirrors its territorial and centralised-caching natural behaviour. A single resident squirrel may maintain multiple food caches within a building’s roof space and will actively defend the entry point against other squirrels.
This means that trapping and removing one individual may immediately attract a replacement territorial animal through the same entry point, reinforcing the primacy of entry point exclusion over reliance on trapping alone.
Commercial facilities should address the physical entry point as the primary management intervention, with trapping as a complementary tool used simultaneously.
Lifecycle
Birth / Pup
Active nesting with pups in a commercial building’s roof space requires a wildlife removal approach that accounts for the presence of dependent young.
Attempting exclusion or trapping of the mother during this period should be coordinated with a licensed wildlife professional to avoid leaving young behind in inaccessible voids.
Juvenile
Juvenile dispersal in early summer and early autumn creates two elevated entry risk windows for commercial facilities. Roofline inspection and sealing before each dispersal period (June and August–September) provides the most effective protection.
Any gaps that were missed in the spring inspection may be found and used by dispersing juveniles.
Adult
Adult red squirrels in a commercial building are the primary management target. Trapping and removal must be combined with permanent exclusion of all entry points — simply removing the resident individual without sealing the entry guarantees replacement by a new territorial animal.
Commercial exclusion materials must be resistant to gnawing (hardware cloth, metal flashing, heavy-gauge wire mesh) rather than standard caulk or foam.
Signs You May Have a Problem
- Persistent scratching, running, or chattering sounds from roof voids or wall cavities — present in all seasons due to the species' year-round wakefulness
- Concentrated food cache (midden) of seeds, cones, and husks discovered during attic or roof void inspection
- Small entry holes (2.5 cm or larger) in fascia, soffit, or roofline material with clean gnaw-mark edges
- Droppings and urine staining concentrated near cache sites in the attic or roof space
- Gnaw damage to electrical conduits, wiring insulation, or wooden roof members found during maintenance inspection
- Staff reports of persistent animal sounds from ceiling voids at any time of year
Risks & Concerns
Commercial risks from red squirrel entry include: fire risk from gnawed electrical wiring in roof spaces and electrical conduits; contamination of HVAC systems with nesting material, urine, and faecal matter; structural damage to insulation, vapour barriers, and roof decking; attracting secondary pests (insects, rodents) through food caches in building voids; and noise complaints from staff in offices adjacent to occupied roof spaces.
Insurance implications of rodent-related fire damage in commercial buildings are significant, and documentation of a known wildlife infestation without remedial action could affect a commercial insurance claim outcome.
Prevention
- Schedule an annual roof and building envelope inspection in August specifically to identify and close squirrel entry points before the autumn entry season
- Install metal flashing or hardware cloth over all identified vulnerable areas — roofline gaps, HVAC penetrations, parapet wall intersections, and aging soffit panels
- Trim all trees and vegetation to maintain a minimum 3-metre clearance from any part of the building envelope that squirrels could reach
- Establish a staff reporting protocol for unusual noises from the roof or ceiling voids so that early entry is detected and addressed promptly
- Include wildlife entry prevention in the facility's pest management agreement, with annual roofline inspection as a scheduled service visit
- Document all wildlife-related building maintenance items and corrective actions for insurance and facility management records
DIY Control
- Commission a professional wildlife inspection to identify all entry points before attempting DIY exclusion — incomplete sealing is ineffective
- Install hardware cloth over all identified entry points using appropriate fasteners for the building material
- Document all entry points and corrective actions for the facility's pest management and building maintenance records
- Consult the pest management provider before using traps to ensure compliance with the Ontario Fish and Wildlife Conservation Act regarding trapping, transport, and disposition of captured wildlife
Professional Control
- Licensed wildlife removal and exclusion service conducted by a provider authorised under the Ontario Fish and Wildlife Conservation Act
- Professional building envelope assessment with prioritised exclusion material installation — commercial-grade galvanised hardware cloth, heavy-gauge wire, and metal flashing
- Post-exclusion attic or roof void inspection to assess damage to insulation, wiring, and structural elements, with remediation recommendations
- Documentation of all wildlife removal, exclusion, and remediation activities for facility management records, insurance files, and pest management programme documentation