History Of The Eastern Fox Squirrel In Missoula, MT


Eastern Fox squirrels (Scuirus niger) have been in Missoula since the 1960’s.  Multiple stories exist on how they arrived here. Generally, the most widely accepted story is that a physician who lived in the mid-west brought them to their property in Missoula.  Eastern Fox squirrels are native to the upper mid-west region ranging from Ohio to Minnesota and south through Illinois and Missouri. Populations have naturally spread westward into Kansas and through North Dakota into eastern Montana via the river systems.  Isolated populations like Missoula’s have come through human movement.  

Eastern Fox squirrels are the largest species of tree squirrel in North America.  They average about 2 pounds with some of our chubbier urban squirrels tipping the scales at over 3 pounds.  These squirrels use leaf ball nests high in the trees or cavities in trees and/or buildings for shelter and rearing young.  Female squirrels come into estrus in mid-winter (December-January) and then again around June. Adult females produce two litters per year with an average of three kits per litter.  With few natural predators populations can quickly increase and expand.  

Diets are varied but largely depend upon geographic location.  These squirrels are quite adaptable and will utilize whatever they have at hand.  In Missoula, the main food source is Norway Maple (Acer platanoides) samaras. They also utilize Box Elder (Acer negundo) seeds, fruit, bird eggs and fledglings, insects, various landscaping plant seeds, and human sources like bird feeders and waste food scraps.

Damage to Native Songbird Nests.

1. Fox squirrels can cause significant damage and problems for people and native wildlife.  Native songbird nests are readily depredated by these squirrels. Observational data have shown steep declines in the songbird populations within Missoula over the last 50 years, some of which can be attributed to squirrels. 

Costly Repairs To Your Homes Electrical Wiring. 

2. Their largest economic impact is when squirrels start using human homes as their own.  Squirrels readily utilize small gaps in fascia trim or soffits to access attic spaces. Once in, they enjoy chewing on the insulated protective layer around electrical wires.  This has caused many power outages and potential fire hazards for homeowners. According to Northwestern Energy, squirrels are one of the top five leading causes of power outages for the company on a yearly basis. Attic insulation makes great nest material and is often used as such.


Increased Heating And Cooling Costs Due To Insulation Damage.

3. Repeated travels through blown-in insulation compacts the insulation, reducing the insulative value.  This causes increased heating and cooling costs for the homeowner.


Exterior Damage to Structure Resulting In Costly Weather And Water Related  Damage. 

4.These squirrels often expand their entry points by chewing the wood and potentially exposing the structure to water and weather damage, resulting in expensive repair bills from general contractors and restoration companies.  


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