101 Ground Squirrel Facts

Are ground squirrels turning your dream garden into a minefield of holes and damaged plants? You're not alone. These common pests can be surprisingly destructive, but the good news is, armed with the right information, you can take control. We've compiled 101 essential facts about ground squirrels covering everything from their sneaky habits and the damage they cause, to key identification tips and proven management techniques. Get ready to become a ground squirrel expert and reclaim your outdoor oasis!

Part 1: Ground Squirrel Basics - Identification & Behavior

1. Ground squirrels are common rodent pests in gardens and landscapes.
2. They often injure plants, carry diseases, and damage land with burrows.
3. Their fur is typically brownish-gray.
4. Adult body length is 9 to 11 inches, excluding the tail.
5. Their tail is 5 to 9 inches long and not as bushy as a tree squirrel's.
6. California ground squirrels are 14 to 20 inches, including the tail.
7. Adult California ground squirrels weigh between 21 and 30 ounces.
8. Male California ground squirrels are slightly larger than females.
9. California ground squirrel fur is mottled brown with white and gray markings.
10. Their belly and underside are lighter browns, grays, and white.
11. California ground squirrels have a distinctive white ring around each eye.
12. Their ears are erect and conspicuous.
13. Ground squirrels live in colonies within burrow systems.
14. They use burrows for sleeping, resting, and rearing young.
15. Burrows also serve as food storage and danger avoidance spots.
16. Ground squirrels are active during the day.
17. They are most active mid-morning through late afternoon.
18. Warm, sunny days see peak ground squirrel activity.
19. Ground squirrels have two periods of dormancy: hibernation and estivation.
20. Most ground squirrels hibernate during winter months.
21. Some young squirrels can be active in mild winter areas.
22. During hot periods, adults enter estivation, a period of inactivity.
23. Estivation can last from a few days to a week or more.
24. During estivation, they plug their burrow entrance with soil near the nest.

Part 2: Ground Squirrel Burrows - Home & Habitat

25. Ground squirrel burrows are typically about 4 inches in diameter.
26. Older burrow entrances can be significantly larger.
27. Burrow systems usually range from 5 to 30 feet in length.
28. Most burrow systems are within 2 to 3 feet of the surface.
29. Some burrows can extend to 6 feet or more in depth.
30. Burrows can be single tunnels or complex branching systems.
31. Burrows may be occupied by a single squirrel or many.
32. Ground squirrels generally forage close to their burrows.
33. Their home range is typically within a 75-yard radius of their burrow.

Part 3: Ground Squirrel vs. Tree Squirrel - Key Differences

34. Ground squirrels will always retreat to a burrow when frightened.
35. Tree squirrels will climb a tree or other tall structure when frightened.
36. Tree squirrels never use a burrow for retreat.
37. Ground squirrels can climb trees, but their primary escape is underground.
38. Tree squirrel tails are generally bushier than ground squirrel tails.

Part 4: Ground Squirrel Damage - What They Impact

39. Ground squirrels eat food-bearing and ornamental plants.
40. Grains, nuts, and fruit trees are particularly vulnerable.
41. They damage almond, apple, apricot, avocado, orange, peach, pistachio, prune, and walnut trees.
42. In gardens, they consume vegetables, especially in the seedling stage.
43. They gnaw on plastic sprinklers and irrigation lines.
44. Ground squirrels girdle young trees by removing bark.
45. They eat twigs and leaves from young shrubs, vines, and trees.
46. Their burrowing causes trip hazards in landscapes.
47. Burrows damage landscapes, making mowing difficult.
48. Burrows and mounds present hazards to machinery.
49. Pedestrians and livestock are at risk from burrow hazards.
50. Burrowing around tree roots can damage and dry them out.
51. Extensive burrowing can sometimes topple trees.
52. Burrowing beneath buildings can cause costly structural damage.

Part 5: Disease & Legal Status - Public Health & Regulations

53. Ground squirrels can harbor diseases harmful to humans.
54. A major concern is bubonic plague, caused by Yersinia pestis.
55. Plague is transmitted by fleas associated with squirrels.
56. Ground squirrels are susceptible to plague, which can wipe out colonies.
57. If you find unusual numbers of dead squirrels, notify public health officials.
58. Do not handle dead squirrels suspected of carrying plague.
59. In California, ground squirrels are classified as nongame mammals.
60. Property owners or tenants can control damaging nongame mammals legally.
61. A trapping license is required for trapping squirrels for hire or profit.
62. The Mohave ground squirrel and San Joaquin antelope squirrel are threatened species.
63. These protected species should not be mistaken for California ground squirrels.
64. Some endangered species, like the San Joaquin kit fox, use old ground squirrel burrows.
65. Be aware of other protected species like kangaroo rats, riparian brush rabbits, and burrowing owls.
66. Read pesticide labels for restrictions near endangered and protected animals.
67. Effective July 1, 2019, nonlead ammunition is required for taking wildlife in California.

Part 6: Ground Squirrel Management - Trapping Strategies

68. Traps are practical for managing low to moderate squirrel numbers.
69. Live-catch traps are generally not recommended due to disposal issues.
70. It is illegal to relocate wildlife off-property in California without a permit.
71. Live-captured squirrels must be released immediately on the property or euthanized humanely.
72. Drowning is not an approved method of euthanasia and is illegal in California.
73. Kill traps include box traps, tunnel traps, and Conibear traps.
74. Place box and tunnel traps near burrows or runways.
75. Bait traps with walnuts, almonds, oats, barley, or melon rinds.
76. Place bait well behind the trigger or tied to it.
77. Acclimate squirrels to traps by placing them unset for several days.
78. To protect pets and children, place box traps inside a covered box with a 3-inch entrance.
79. Place the covered box near active burrows.
80. Trapping is most effective between February and October.
81. When using box-type traps, place them out with triggers unset for several days.
82. After squirrels are used to taking the bait, rebait and set the traps.
83. Inspect traps at least once a day and remove dead squirrels.
    
84. Inspect traps at least once a day and remove dead squirrels.
85. Use protective gear, like a plastic bag, when handling carcasses.

Part 7: Ground Squirrel Management - Fumigation & Baits

86. Ground squirrel management works best when understanding their life cycle and behavior.
87. Burrow fumigation is most effective in spring or when soil moisture is high.
88. Moist soil helps contain the gas within the burrow system.
89. Do not fumigate in summer or dry soil conditions as gas diffuses easily.
90. Do not fumigate during hibernation as squirrels plug burrows.
91. Read and follow all fumigant label instructions for safety.
92. The most readily available fumigant for residential users is the gas cartridge.
93. Puncture the cartridge cap, insert fuse, and place in active burrow.
94. Light the fuse and push the cartridge into the burrow with a shovel.
95. Immediately seal and tightly pack the burrow opening with soil.
96. Seal any additional burrow openings where smoke escapes.
97. Larger burrow systems may require multiple cartridges.
98. Check for reopened burrows after 24 hours and re-treat as needed.
99. Toxic baits containing first-generation anticoagulant rodenticides (e.g., diphacinone) are limited for residential use.
100. These baits must be applied in tamper-resistant bait stations.
101. Ongoing management is necessary for properties next to wildlands or squirrel-prone areas, as squirrels will reinvade over time.