The Columbian ground squirrel (Urocitellus columbianus) is one of the most abundant and widely distributed small mammals in western Montana. Highly social and colonial, these ground-dwelling squirrels are a familiar sight in meadows, pastures, roadsides, parks, golf courses, and suburban yards from the valleys to subalpine elevations. Their upright alert posture and sharp whistle alarm call are iconic elements of the Montana landscape.
Unlike tree squirrels, Columbian ground squirrels spend the vast majority of their lives underground. A single colony can contain dozens of animals, each maintaining an extensive burrow system with multiple chambers — food storage, nesting, and sleeping areas — and multiple entrances. Burrow networks in heavily colonized pastures or lawns can be both dense and deep, with documented tunnel systems extending several feet below the surface.
They are true hibernators, spending roughly 7–8 months of the year underground (typically early August through March), which concentrates their active foraging and burrow expansion into a compressed spring and summer window. During this active period, the damage to lawns, gardens, pastures, crops, and sub-surface infrastructure can be significant.
Size
9–11 inches; 8–16 oz
Color
Tawny-brown with mottled back; orange-buff face
Active Season
March–August (hibernate remainder of year)
Risk Level
Medium–High (structural undermining; agricultural damage; livestock injury risk)
Habitat
Meadows, pastures, lawns, roadsides, golf courses
Litters
Can be dozens of animals in a single area
SIGNS OF INFESTATION
Identifying Columbian Ground Squirrel Activity
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Burrow entrances — 3–4 inch diameter holes in the ground, often with a low mound of excavated soil. Multiple entrances per colony.
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Upright sentinel posture — Animals standing upright on hind legs scanning for predators — a highly visible behavior in open areas.
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Whistle alarm calls — A sharp, piercing whistle when the colony detects a threat.
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Stripped vegetation — Closely clipped grass and grazed plant stems near burrow entrances from foraging activity.
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Subsidence or soft spots in lawn — Areas where the ground feels spongy or hollow underfoot indicate extensive burrowing below.
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Crop or garden damage — Seedling removal, root excavation, and foraging damage in planted areas.
HEALTH RISKS
Columbian ground squirrels are a known reservoir host for fleas carrying bubonic plague (Yersinia pestis) in the western United States. While human plague cases are rare, the risk is real and documented — and any die-off of ground squirrels in a colony should be treated with caution as it can indicate plague activity. They also carry tularemia and leptospirosis. Ground squirrel fleas can bite humans and pets, creating an indirect transmission pathway for these diseases. Montana residents working or recreating in areas with ground squirrel colonies should use insect repellent and be aware of the plague risk.
PROPERTY DAMAGE
Burrow networks undermine the structural integrity of soil beneath lawns, fields, roads, embankments, and building foundations. Livestock stepping into burrow entrances sustain leg injuries — a serious and costly problem on ranches and farms. Riding, ATVing, or mowing over heavily burrowed ground creates similar hazards. Agricultural damage includes direct consumption of crops, pasture degradation, and hay field damage from burrowing that interferes with irrigation. Golf course and park managers with ground squirrel colonies face significant ongoing maintenance and turf damage costs.
