How Do Squirrels Reproduce?


Squirrels belong to the taxonomic family Sciuridae which includes about 286 species. These are grouped into three main types known as tree squirrels, ground squirrels and flying squirrels. These small mammals stand out for their agility, with even ground squirrels being very nimble when climbing or running. They are very active animals, although they are more active at certain times than others. They also play an important role in the ecosystems in which they live, helping to disperse seeds and ensure plants grow. For them to be able to do so, reproduction is essential. AnimalWised learns more about squirrel mating behavior by asking how do squirrels reproduce?
What type of reproduction do squirrels have?
Squirrels are placental mammals, something which informs the type of reproduction they carry out. As in almost all members of this group, embryonic development occurs within the maternal uterus and is mediated by a placenta. This temporary organ allows the transfer of nutrients and oxygen from the mother to the embryo during gestation, ensuring proper development.
For gestation to occur, the fusion of gametes has to occur. As with all mammals, squirrels reproduce sexually and carry out internal fertilization. This means the male has to mate with the female to introduce the sperm to the egg so internal fertilization can occur.
Female squirrels typically have seasonal estrous cycles that can vary according to species and environment. The mating system of sciurids is polygynandrous, meaning that multiple males may mate with multiple females. They compete through courtship rituals and other pre-mating reproductive behaviors. Females typically select mates based on traits of skill and vitality, thereby best ensuring the genetic survival of the species.
Squirrels carry out sexual reproduction and internal fertilization, but you can learn about other modes of reproduction in animals with our related guide.
How do squirrels reproduce?
While there are some generalizations we can make about how do squirrels reproduce, the specifics can change according to species. This means squirrel mating behavior is not uniform. We can better understand it by looking at the mating behavior of the different types of squirrels we mentioned in the introduction:
How do flying and tree squirrels reproduce?
The reproductive process of flying squirrels begins with the maturation of the young animal. When sexually mature, males develop functioning testicles and females experience genital swelling when they are ready to mate. The latter can leave chemical markings that males identify by smell. Males will seek out females and even start chasing them when they are sexually active.
After maturation, a courtship can begin. Usually several males chase a female at full speed through the branches of trees. This can be up to around 9 individual males chasing a single female.
Both male and female tree squirrels tend to be solitary animals, living in dispersed populations. Some flying and ground squirrels may live in groups, but territoriality will depend on the species. For example, red squirrels (Sciurus vulgaris) tend to be very territorial, while the eastern gray squirrel (Sciurus carolinensis) is not so much. With territorial squirrels, males are forced to defend part of the territory to attract a female.
When is squirrel mating season?
In several types of squirrels, two reproductive peaks occur per year. One lasts from December to January and the other from May to June. This is especially common in North American species.
The dominant male is the fastest and most agile. He will stand out from the rest and will be accepted by the female. Copulation then occurs. Afterwards, the couple separates and begins to chase each other again. In this way, multiple copulations occur, both in females and males. This is a mating behavior designed to better ensure fertilization has occurred.
When is ground squirrel mating season?
Although tree squirrels and flying squirrels do not, ground squirrels hibernate. This affects their reproductive activity, resulting in a different mating system since they are mostly dormant in winter. Shortly after hibernation ends, female ground squirrels go into heat. This begins the mating season of ground squirrels. For this reason, the rituals of ground squirrels are very difficult to study and poorly known compared to other squirrels.
Learn more about this seasonal behavior with our article asking do squirrels hibernate in winter?

How are squirrels born?
As with almost all mammals, squirrels carry out live birth. This means squirrel young do not hatch from eggs outside the mother. The gestation period for squirrels varies between 30 and 65 days, depending on the species. Generally speaking, smaller species have shorter gestation times than larger ones. The embryo develops inside the mother during this time, being protected and nourished by the placenta.
Depending on the type of squirrel, females prepare a nest either in hollow trees, dense branches or in underground burrows. They use leaves, moss, fur and other materials to ensure the comfort and safety of the young. To learn more about squirrel habitats, our article on where do squirrels live provides useful information.
When it is time to give birth, squirrels usually give birth to litters of at least four babies. Newborn squirrel babies are known as kits. They are altricial, meaning they cannot look after themselves. They are born blind, hairless and wholly dependent on their mother. The fathers have no role in caring for the young.
A litter of squirrel kits may all be from one male, but they can also have multiple paternity. This occurs when the mother mates with several males during the same period of her estrus cycle. Although the fertilization may not occur at the same time, the gestation synchronizes and results in a single birthing event. In this litter, there may be kits which have different fathers.

What do baby squirrels look like?
Newborn squirrel babies weigh just a few grams and measure around 3 to 5 centimeters in length, depending on the species. Their bodies are pink and hairless, being immediately exposed to predators and adverse weather conditions as soon as they are born.
During the first few weeks, they depend exclusively on their mother's milk. This is rich in essential nutrients for their rapid development. As we mentioned before, only the females care for the babies. In some cases, groups of females stay together for breeding, even if they are otherwise solitary.
Early growth of newborn squirrel kits includes the:
- Gradual appearance of fur
- Opening of the eyes
- Development of their motor skills
For flying squirrels, these stages also include strengthening of the patagium. This is the membrane that allows them to glide, highlighting differences in how flying squirrels reproduce compared to their terrestrial counterparts.
Flying squirrels do not have proper flight ability. Instead, they glide between trees thanks to the patagium. Learn more in our article on types of mammals that can fly.

When do squirrels sexually mature?
The growth of a squirrel is a rapid but critical process, which takes approximately 12 weeks until the babies become independent. Although only a rough guide, we can see squirrel development exemplified as follows:
- Between three and five weeks of age: they begin to develop their teeth and explore the environment near the nest.
- At eight weeks: most kits are fully furred, being able to climb trees and forage under their mother's supervision.
Growth and sexual maturity of squirrels varies between species. Some squirrels may be independent and leave their mother after 28 days, reaching sexual maturity around day 87. Others develop after 42 days and are sexually mature at 3 years.
As they grow, squirrel young learn a variety of strategies from their mothers, such as how to feed themselves and how to move around in trees or on the ground. In the case of flying squirrels, this learning includes practice in how to glide, which is vital for this group.
Discover more about conservation of these rodents with our article asking is it OK to keep squirrels as pets?
If you want to read similar articles to How Do Squirrels Reproduce?, we recommend you visit our Facts about the animal kingdom category.
- Brown, E.; A. Peri and N. Santarosa. (2014). " Sciuridae ." Animal Diversity Web.
https://animaldiversity.org/accounts/Sciuridae/ - Koprowski, J.L. (1998). The evolution of arboreal polygyny in tree squirrels. Journal of Mammalogy, 79(1), 237-246.
- Martin, P.H., & Anthony, M.B. (2020). Nocturnal behavior and gliding adaptations in flying squirrels. Journal of Mammalian Behavior, 45(2), 120-134.