Squirrels and rats share some superficial resemblances, leading many to question their biological connections. A scientific examination of their classification and characteristics reveals their distinct identities and unique adaptations, despite shared ancestry.
The Rodent Family Tree
Squirrels and rats are indeed related, both belonging to the extensive mammalian order Rodentia. This order encompasses over 40% of all mammal species, making it the largest group. The defining characteristic shared by all rodents is the presence of a single pair of continuously growing incisors in both their upper and lower jaws. These chisel-like front teeth require constant gnawing to keep them worn down, preventing them from growing too long and causing harm to the animal.
Within the Rodentia order, squirrels and rats diverge into different families. Squirrels are classified under the family Sciuridae, which includes tree squirrels, ground squirrels, chipmunks, marmots, and prairie dogs. The Sciuridae family is found across the Americas, Eurasia, and Africa. Rats, conversely, belong to the family Muridae, the largest family within Rodentia, comprising over 1,383 species. Murids are found nearly globally, inhabiting a wide range of ecosystems.
Unpacking the Differences
Despite their shared classification as rodents, squirrels and rats exhibit numerous distinctions in their physical characteristics, habitats, behaviors, and diets. These differences highlight their adaptation to varied ecological niches.
Physical traits offer clear ways to differentiate these animals. Squirrels typically possess robust, bushy tails covered in thick fur, which often curl upwards, and soft, silky fur that varies widely in color, with furred feet. In contrast, rats have thin, scaly tails that are sparsely haired or hairless and tend to stay vertical. Their fur is often coarse and can be brown, gray, black, or white, with hairless feet and “hands.” Squirrels also tend to be larger, measuring around 15-20 inches including their tail, while adult rats can reach up to 16 inches.
Their preferred environments and daily routines also differ significantly. Squirrels are primarily diurnal, meaning they are active during the daytime, and are often seen foraging for food. They are commonly found in arboreal habitats, building nests in tree cavities or constructing dreys from leaves and twigs high in trees. Rats are largely nocturnal, being most active at night, and they tend to be ground-dwelling. They establish nests in burrows underground, in dense vegetation, or within structures like basements or walls, utilizing materials such as shredded paper or insulation.
Dietary habits present another area of divergence. Squirrels are largely herbivorous, with their primary food sources being nuts, seeds, and other plant materials like roots and mushrooms. They are known for caching food for later consumption. Rats are omnivorous and highly opportunistic feeders, consuming a wide array of items including grains, fruits, vegetables, and even meat or food scraps. Their adaptable diet allows them to thrive in diverse environments, including urban settings.