Winter has arrived, which means most pests should be taking a break, right? Wrong.
If you live in California, one critter you likely won’t get a winter break from is the California ground squirrel. While these rodents may be less visible during the winter, they are no less active.
In this blog, we’ll share a few critical California ground squirrel hibernation facts and discuss how you can control these pests on your property during the winter months.
Do California Ground Squirrels Hibernate in the Winter?
No. Most California ground squirrels do not hibernate in the winter. The only exception is populations of ground squirrels in inland areas with extreme seasonal temperature variations.
While those squirrels do hibernate, that is considered a relatively rare ground squirrel behavior here in the Golden State.
In the coastal areas of Southern California, these little rodents are active throughout the year. In places like the San Joaquin Valley, ground squirrels are less active during winter but don’t truly hibernate.
What do Ground Squirrels Do in the Winter?
During the winter, ground squirrels focus on conserving their energy and finding the food they need to make it through the season.
This means they spend much of their time foraging for food near their burrows, resting with the other squirrels in their colonies, and breeding during late winter.
Fascinatingly, less active ground squirrels regulate their blood concentrations during the winter months, redirecting electrolytes like sodium to be stored in areas of the body like the bladder, which helps the animals stay hydrated when food is scarce.
In California, mating starts as early as January (in warmer parts of the state) and can continue until July, with the breeding season peaking between March- June.
Where Do They Go?
California ground squirrels don’t go anywhere different during the winter. Instead, they spend more time in their underground burrows, living in colonies of 2-20 (or more) animals.
Ground squirrel burrows are usually between 5-30 feet long and about 2.5-4’ below the surface of the soil.
In the winter, they may dig even deeper to get below the frost line. When they come out to feed, ground squirrels will travel about 75-100 yards from their burrow entrance before darting back into the safety of their tunnels.
What Do They Eat?
Ground squirrels are herbivores, and their diet changes seasonally. They feed on fresh, green grass and herbaceous plants in the spring.
They’ll eat grains, nuts, and seeds during the winter or drought periods when food is scarce. They store food in their burrows to ensure they have enough food for the winter.
What Damage Do They Cause?
Even in the winter, ground squirrels can cause extensive damage to ornamental and food-bearing plants. Thanks to their sharp teeth, they’re skilled chewers who can decimate grain crops and fruit and nut trees. They’re especially fond of apple, apricot, orange, and peach trees.
Ground squirrels can destroy or consume tender young seedlings in gardens and landscaping as they search for food.
They may also use their teeth to strip the bark from young shrubs or to gnaw the leaves off vines, girdling tree trunks and killing young plants. Ground squirrels will also chew on underground irrigation and utility lines and can destroy sprinkler heads.
When they dig burrows, ground squirrels create mounds that can damage farm or lawn machinery, cause a hazard for people and livestock, and even create soil instability that threatens the foundations of buildings.
When they dig near trees, they can displace so much soil that a tree’s root system dries out, eventually toppling and killing the tree.
Finally, ground squirrels can carry diseases that are dangerous for people, domestic pets, and livestock.
The most common ground squirrel disease is bubonic plague, which can be transmitted to humans and pets via infected fleas carried by the squirrels.
6 Winter Ground Squirrel Control Tips
Protect your property from ground squirrel damage in the winter with these tips:
1. Clean up your yard
Ground squirrels are prey animals, so they use brush and vegetation for shelter.
Remove brush, woodpiles, and other debris to make your yard less attractive for ground squirrels.
In addition to removing hiding places, cleaning up your yard makes it easier to spot new ground squirrel mounds and burrows.
Pros: Effective, helps reduce the incidence of other pests, can discourage ground squirrel re-infestation, humane
Cons: Labor-intensive, won’t kill existing ground squirrels
2. Rip out old burrows
Ground squirrels are opportunists and may invade (or reinvade) a site by moving into vacant burrows.
Prevent this by destroying any old, vacant burrows you find. We recommend using a tractor and ripping bars to rip the burrows to a depth of at least 20” to destroy the burrow and its entrance.
Filling the burrows with dirt won’t work since the ground squirrels will just dig through the soil to reopen the tunnel.
Pros: Effective at reducing reinfestation, non-toxic, humane
Cons: May not be possible in urban areas
3. Trap ground squirrels
Traps are a humane, effective way to control large ground squirrel populations, and both live-catch and lethal traps exist.
While we always advise humane pest removal, it’s important to note that it is illegal to relocate wildlife in California. If you use live-catch traps, all animals must be immediately and humanely euthanized on-site or released in the same area where they were caught.
With that in mind, there are many lethal traps that kill ground squirrels immediately. The most common include box traps and tunnel traps.
Note: If you’re going to trap ground squirrels, you must treat the animals humanely. Check traps at least daily and promptly euthanize or release all trapped animals. Handle animals carefully to avoid scaring or stressing them, and protect yourself by wearing long pants, a long-sleeved shirt, and heavy gloves.
Pros: Effective, fast-acting, ideal for controlling large populations of ground squirrels
Cons: Above-ground box and tunnel traps are hazardous to kids, pets, and non-target species, all traps must be checked regularly and reset if they do not catch ground squirrels, traps require you to dispose of dead squirrels, which can present a risk of disease
As a treatment method, fumigation is most effective in the late winter or early spring when soil moisture levels are high enough to contain the gas within the burrows.
If you use fumigants like gas cartridges or aluminum phosphide, read and follow all label instructions carefully.
Be aware that fumigants are subject to restrictions that prohibit application within a certain distance of occupied structures.
Pros: Kills ground squirrels quickly, works to control large populations
Cons: Fumigants are highly toxic and unsafe for kids, pets, and all non-target species, unless soil conditions are ideal, fumigant gas can diffuse through small cracks in the soil, presenting a threat to the person using the fumigant
Today, most baiting is conducted with anticoagulant rodenticides with active ingredients like diphacinone.
All baits must be deployed in tamper-resistant bait stations placed a certain distance away from all structures, and only certain baits are available for residential use.
Pros: Effective, ideal for controlling large ground squirrel populations
Cons: Toxic baits are highly poisonous and are unsafe for kids, pets, and non-target species, even if baits are properly secured, non-target species may consume poisoned ground squirrels, most first-generation anticoagulants are considered multiple feeding toxins, meaning the ground squirrels must consume the bait several times over an extended period to ingest a toxic dose, baits take about 2-4 weeks to control ground squirrel populations effectively, some baits can only be applied by licensed pest management professionals, baiting is most effective in the spring or summer when ground squirrels are feeding on seeds – while baiting can be effective in the winter, it requires more bait.
6. Monitor your property
Possibly the most important control tip we can offer is to monitor your property carefully. All pests, ground squirrels included, only appear when the conditions are ideal, and catching them early is the best way to keep populations in check.
Monitor your property for ground squirrels all year round, even during winter. Be on the lookout during times such as midmorning, when ground squirrels tend to leave their burrows to feed.
Be sure to note the appearance of any new burrows or mounds, and check areas like ditches, road banks, crops, and fence lines for recent ground squirrel activity.
If you want to make your monitoring efforts even more effective, consider enrolling in our annual pest management plan. When you invest in this plan, one of our pest control experts will visit your property seasonally, inspecting for signs of new pest damage or infestation and delivering treatment or follow-up treatment as needed.
It’s the best way to keep your property pest-free 365 days a year.
Pros: Effective, ideal for reducing the presence of ground squirrels and other pests, humane, non-toxic
Are Ground Squirrels Taking Over Your Bay Area Yard this Winter? We Can Help!
Ground squirrels can be destructive all year, even during winter. Fortunately, you don’t have to sit by and watch them destroy your lawn or garden.
Smith’s Pest Management is here to help!
Providing comprehensive, humane, effective ground squirrel control for customers throughout the Bay Area, we’re here to help you control your ground squirrel populations and reclaim your space.