Seasonal Activity

The effectiveness of most control methods is influenced by seasonal changes in ground squirrel behavior. Understanding hibernation and mating periods is essential for efficient ground squirrel management.
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​California Ground Squirrel

Hibernation and Estivation

California ground squirrels may have two periods of dormancy during the year:
  1. Summer: Estivation is a period of dormancy that takes place during a hot or dry season. California ground squirrels typically estivate in periods of extreme summer heat (July and August. All populations of California ground squirrels found at high elevations generally estivate. At lower elevations, the adults often estivate for at least a portion of the year, though juveniles may still remain active at this time.
  2. Winter: California ground squirrels generally hibernate during the winter. They can emerge from their burrows as early as the end of January, but some populations are not seen above-ground until March. Male California ground squirrels often emerge from hibernation 10 to 14 days before females. In Southern California, some populations of California ground squirrels do not hibernate due to mild weather during the winter months. 

Reproduction
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The onset of breeding in California ground squirrel populations can vary depending on weather, elevation, and latitude. Generally, populations at higher altitudes and in colder climates hibernate for longer periods and therefore breed later. Mating can start as early as January in warmer locations and continues until July. Peak mating occurs from March through June.
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In a year, California ground squirrels only produce a single litter. The average litter has 5-8 young, but litters as small as 1 and as large as 15 have been observed.
California ground squirrel activity chart
(click chart to enlarge)

Belding's Ground Squirrel

Hibernation

Belding's ground squirrels spend the majority of their time in hibernation, from which they emerge in late spring.  During the summer, Belding’s ground squirrels forage on green vegetation and almost double their weight in preparation for the long hibernation period ahead. Beldin’s ground squirrels hibernate in and around the end of July. Males tend to hibernate alone and females usually hibernate in groups. The hibernation period can last for five to seven months. Males emerge first and are followed by the females two weeks later.

Reproduction
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The mating season occurs from late May to early June. The young are born 23 to 28 days after conception. Females produce one litter of 3-8 young per year. Younger females typically produce larger litters. Young are weaned at about one month old and typically stay with their mother for an additional two weeks. In general, young females develop their own burrows within the colony, while males leave to find their own territories after weaning. 
Belding's ground squirrel activity chart
(click chart to enlarge)