Are Ground Squirrels Dangerous? Plague, Bites, and Public Health

California ground squirrels are not aggressive animals — they do not attack humans and do not seek confrontation. However, they carry genuine public health risks that make large infestations a more serious concern than simple property damage. Understanding these risks helps property owners make informed decisions about the urgency of treatment.

Plague: The Most Serious Risk

Yersinia pestis — the bacterium that causes plague — remains active in California wildlife populations, including California ground squirrels. This is not a historical curiosity. The California Department of Public Health and county health departments throughout Southern California issue regular advisories about plague activity in ground squirrel populations, particularly in San Bernardino, Riverside, and Los Angeles counties. Cases of human plague are documented in California periodically, and the primary transmission pathway is flea bites from infected rodents.

Ground squirrels are reservoir hosts for plague — the bacterium circulates in squirrel populations and is transmitted between squirrels via fleas. When infected squirrels die, their fleas seek new hosts, which may include pets, other wildlife, or humans. Dead ground squirrels found in an area with an active colony are a warning sign of possible plague activity in that population. County health departments advise against handling dead ground squirrels and recommend prompt notification if multiple dead animals are found in a short period.

The risk is most significant for properties adjacent to wildland-urban interface areas in the Inland Empire, Foothill communities, and other areas where squirrel populations connect with natural terrain. Urban colonies in densely developed flatland areas present lower but not zero risk.

Flea Transmission to Pets

Dogs and cats that come into contact with ground squirrels or their burrow areas can acquire fleas that may carry plague or other pathogens. This is a practical everyday risk separate from the dramatic plague scenario — pet flea infestations on properties with active ground squirrel colonies are common. Year-round flea prevention for pets on properties with ground squirrel activity is strongly recommended by veterinarians in endemic areas.

Bite Risk

Ground squirrels do not attack unprovoked, but cornered or handled animals will bite. Bites from wild rodents require medical evaluation because of rabies risk — though ground squirrels are not considered high-risk rabies vectors, any wild animal bite warrants prompt medical attention. Children who try to hand-feed apparently tame ground squirrels in parks and campgrounds account for most bite incidents.

Hantavirus

California ground squirrels can carry hantavirus, though they are not the primary reservoir species in California (deer mice are). The risk from ground squirrels is lower than from deer mice but not zero. Disturbing burrow material — cleaning up after a colony — should be done with a dust mask and gloves, and dry sweeping of rodent droppings should be avoided.

When to Contact the Health Department

If you find multiple dead ground squirrels in a short period, contact your county vector control or health department before disturbing the area. This is the scenario that can indicate active plague circulation in the local population and warrants professional assessment before anyone — including pest control — disturbs the burrows.

Related Articles

• California Ground Squirrel — Complete Behavior and Control Guide
• Ground Squirrel Damage to Property
• Gopher vs. Ground Squirrel — How to Tell the Difference

Call 909-599-4711 for ground squirrel control throughout Southern California. Large colonies near homes with children or pets warrant prompt treatment.