Distinguishing between male and female squirrels can be challenging due to their similar appearances. However, careful observation of physical features and behaviors can provide clues to a squirrel’s sex.
Physical Characteristics for Identification
The most reliable way to differentiate male from female squirrels involves examining their genital area. Male squirrels possess external testicles and a penis, with a noticeably greater distance between their genital opening and the anus, typically about 1 centimeter (0.4 inches). In contrast, females have a vulva, and their genital opening is located very close to the anus.
Male testicles become more prominent during breeding seasons, typically late winter to early spring and summer. Outside these periods, testicles may retract, becoming less noticeable or invisible. Young males might not display visible testicles until around one year old.
Female squirrels possess mammary glands, with nipples becoming more visible when pregnant, nursing, or during breeding season. Active nipples may appear swollen and pink. Outside reproductive periods, nipples are usually flattened and hidden within their fur.
Male and female squirrels generally appear similar in overall size, coloration, and build. Therefore, relying solely on general appearance is not a dependable method for sex identification.
Behavioral Observations
Observing a squirrel’s behavior can also offer insights into its sex, although these cues are often less definitive than physical ones and can be seasonal.
A clear indicator of a female squirrel is her involvement in a “mating chase,” where she is pursued by multiple males. During these chases, the female emits a scent that attracts males.
Female squirrels are solely responsible for building and maintaining dreys, which are nests for raising young. They select safe locations like tree cavities or leaf nests. A squirrel observed carrying nesting material or frequently returning to a drey is likely a female preparing for or caring for offspring.
Direct parental care is another behavioral clue. Female squirrels nurse, clean, and protect their young. Male squirrels do not participate in rearing or provide parental investment after mating. Therefore, any squirrel seen interacting with or guarding young is almost certainly a female.
Factors Making Identification Challenging
Accurately identifying the sex of a squirrel can be difficult for several reasons.
Squirrels are agile and wary creatures, making it challenging to get a clear, close-up view of the subtle physical features needed for identification. Their constant movement and small size further complicate observation.
Many reliable indicators, such as visible testicles or prominent nipples, are seasonal. These features are most noticeable during breeding or nursing periods, becoming less apparent or disappearing entirely outside these times.
Individual squirrels vary significantly in size, coloration, and behavior, regardless of sex. This variation means general appearance or certain behaviors are not always definitive indicators. Specific characteristics can also vary slightly among the over 200 squirrel species. Despite these challenges, combining physical and behavioral cues improves the likelihood of accurate sex identification.