The common question of whether squirrels are simply rats with furry tails arises from their similar size and general rodent appearance. While both squirrels and rats belong to the expansive order Rodentia, implying a shared distant ancestry, they are distinct animals with notable differences in their biological classification, physical characteristics, and behaviors. This article will clarify their relationship, highlighting what makes them unique.
The Rodent Family Tree
Both squirrels and rats are part of the order Rodentia, a group of mammals characterized by a single pair of continuously growing incisors in both their upper and lower jaws. These teeth require constant gnawing to prevent overgrowth. The term “rodent” itself originates from the Latin word “rodere,” meaning “to gnaw.” Rodentia is the largest order of mammals, encompassing about 40% of all mammal species, found across nearly all terrestrial habitats globally.
Despite this shared order, squirrels and rats diverge significantly at the family level of classification. Squirrels belong to the family Sciuridae, which includes tree squirrels, ground squirrels, chipmunks, and marmots.
In contrast, common rats, such as the Norway rat (Rattus norvegicus) and the black rat (Rattus rattus), fall under the family Muridae. Their placement in different families means they are not as closely related as, for instance, different types of squirrels or different types of rats.
Shared Traits and Unique Features
Squirrels and rats share general rodent characteristics beyond their continuously growing incisors, such as their adaptability to various environments and their omnivorous diets, though their specific preferences vary. Both can thrive in human-modified landscapes, often seeking food and shelter in close proximity to human activity.
However, distinct physical and behavioral differences distinguish them. The most apparent difference is their tail: squirrels possess a large, thick, and bushy tail, which they use for balance when climbing, communication, and even as a blanket for warmth. In contrast, rats typically have thin, scaly, and sparsely haired tails that are often as long as their bodies.
Their typical habitats and activity patterns also differ. Tree squirrels are primarily arboreal, living in trees and active during the day (diurnal), often seen in parks and forests. They construct nests in tree cavities or build leaf nests. Rats, especially common species like Norway rats, are associated with urban environments, sewers, and ground burrows, and are predominantly nocturnal. While some rat species can be arboreal, most are terrestrial burrowers.
Regarding appearance, squirrels generally have a more slender and agile build compared to the stockier body of common rats. Squirrels tend to have larger eyes relative to their face size and fur covering their feet, while rats have more pointed heads, smaller ears, and hairless feet. Their diets, while both omnivorous, show different tendencies: squirrels consume nuts, seeds, and fruits, often burying them for later. Rats are highly opportunistic scavengers, eating a wider range of available food, including human refuse.