Squirrel

Aurora Rodriguez

General Information

Habitat

Found Worldwide
Native to all terrestrial regions
Vary from trees to underground burrows
- Rainforests
- Grasslands
- Artic Tundras
- Forests
- Suburban areas & cities
Also found in high elevations

-Example: Himalayan marmots

(Brown et al., 2014)

Social Structure

Mostly solitary their whole lives
- Exception: live in groups during mating season & during the Winter
Nonmonogamous mating
Considered "promiscuous," as they mate with several
A squirrel lives for 5 to 6 years, though this can vary by species.
Dominance hierarchy depends on a combination of size and age
- The larger the squirrel, the more likely it is to be dominant

(Wildlife Online, 2025)

Communicative Behavior

Squirrels have a diverse set of calls when communicating with one another
- Alarm calls: to warn others of predators, or directly with the predator
- Agonistic calls: include aggression and annoyance
- Territorial calls
- Affiliative calls help maintain social connections, reunite individuals. As well as maintaining group cohesion

Mating calls: one or both sexes may emit calls before, during, or directly after copulation

Vocalizations are categorized in three groups
- Advertising, Approach, and Copulation
Scent marking includes rubbing of the body, urinating for marking territory and breeding season

Posture and movement: tail positioning and stomping of feet

(Diggins, 2021)

Reproductive Behavior

Mating system: polygynous
2 peak times of reproduction
- December-January
- May-June

The development of male testes and the sexual swelling of females mark the breeding season
Males, at times, follow the scent left by estrous females or might simply chase
Gestation ranges from 29-65 days, depending on the size of the species
A male can fertilize an entire litter, though usually there is a varying paternity
They are altricial at birth

(Brown et al., 2014)

Taxonomy

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Sciurus

(Brown et al., 2014)

Relating to Nutritional Ecology

Feeding Behavior

The diverse diet of a squirrel categorizes them as omnivores
They have strong, chisel-like incisors and powerful jaws, allowing them to eat dense food such as tree bark and nuts
Their diet also includes: fungi, caterpillars, grasshoppers, beetles, fruits, and seeds.
Occasionally, they consume bird eggs, nestlings, carrion (decomposing animals), and some small vertebrates, such as toads or frogs.
However, the diet of a squirrel differs based on its environment:
- For example, the tropical ground squirrels. Their environment is the forests of Southeast Asia, so their diet consists of arthropods.

(Briticanna Editors, 2025)

Digestive Anatomy

Squirrels are hindgut fermenters, specifically cecal digesters.
- They have a monogastric stomach.
- Before getting chemically digested, their food is first mechanically ground by their teeth.
- Their enlarged cecum is essential for their fiber-rich diet. The microbes inside their cecum digest cellulose! It also acts as food storage.

(Sadeghinezhad, 2012; Wildlife Online, 2025)

Nutritional Ecology

Physical adaptations:

The oral structure of a squirrel consists of premolars, molars, canines, and incisors.
A special characteristic of their oral structure is that their teeth continue to grow, enabling them to consume dense food.
The ability to turn their hind feet to face backward allows them to easily climb down trees headfirst.
A heightened sense of smell enables them to detect stress levels among themselves and identify threats.
Their eye shape are specialized for high levels of light and are tilted upward, which allows for spotting predators more easily.

Behavioral Adaptations:

Squirrels forage for their food and other resources in trees. Their preference for trees allows them to easily escape predators and other threats in their area.
Squirrels scatter horde sources such as nuts and seeds. This is beneficial as they do not hibernate.

Digestive Adaptation

Due to the high fiber diets of squirrels, the cecum is one of the most important compartments of the digestive tract.
The enlarged cecum of a squirrel harbors microorganisms that can break down plant material.

(Alabama Wildlife Federation, 2014; Lu and Hsiao-Pe, 2018; Wildcare, 2020)

Reference List

Alabama Wildlife Federation. 2024. Wonders of Wildlife: Eastern Gray Squirrel. alabamawildlife.org/wonders-of-wildlife-eastern-gray-squirrel. (Accessed 02 December 2025.)
Britannica Editors. 2025. What Do Squirrels Eat? https://www.britannica.com/science/What-Do-Squirrels-Eat. (Accessed 16 November 2025.)
Brown, E. M. Peri, A. M., and N. A. Santarosa. 2014. "Sciuridae" (On-line), Animal Diversity Web. https://animaldiversity.org/accounts/Sciuridae/. (Accessed 16 November 2025.)
Diggins, C. A. 2021. Behaviors associated with vocal communication of squirrels. Ecosphere. 12(6):1-27. https://doi.org/10.1002/ecs2.3572.
Lu, H.P., P.Y. Liu, Y.B. Wang, J.F. Hsieh, H.C. Ho, S.W. Huang, C.Y. Lin, C.H. Hsieh, and H.T. Yu. 2018. Functional Characteristics of the Flying Squirrel’s Cecal Microbiota Under a Leaf-Based Diet, Based on Multiple Meta-Omic Profiling. Front. Microbiol. 8: 1-13. https://doi.org/10.3389/fmicb.2017.02622
Nzalak, J. O., N. Wanmi, and M. O. Samuel. 2015. Morphometric Study on the Digestive System of the Wild Gray Squirrel (Sciurus carolinensis). J. Vet. Anat. 8(2): 59-68. https://doi.org/10.21608/jva.2015.44867.
Wildcare. 2020. Squirrel Dentition. discoverwildcare.org/squirrel-dentition. (Accessed 02 December 2025.)
Wildlife Online. 2023. Squirrel Food & Feeding - Diet Composition. www.wildlifeonline.me.uk/animals/article/squirrel-food-feeding-diet-composition. (Accessed 04 December 2025.)
Wildlife Online. 2025. Squirrel Behaviour - Dominance, Aggression & Territoriality. https://www.wildlifeonline.me.uk/animals/article/squirrel-behaviour-dominance-aggression-territoriality. (Accessed 16 November 2025.)

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