The term “vole” refers to a diverse group of small rodents primarily belonging to the subfamily Arvicolinae, which also includes lemmings and muskrats. Often mistakenly called field mice or meadow mice, voles represent a distinct lineage of over 150 different species. This variety, adapted to different habitats across the Northern Hemisphere, results in a significant spread in body size, explaining why some voles are among the smallest mammals while others approach the size of a small rat.
The Maximum and Minimum Size of Voles
The overall size range for voles is considerable, extending from tiny, mouse-sized individuals to much larger, stout creatures. Total length, measured from the head to the tip of the tail, generally falls between 8 and 23 centimeters (3 to 9 inches), depending on the species. This measurement includes their characteristic short tail, a defining physical trait that distinguishes them from many other rodents.
In terms of mass, the smallest adult voles weigh less than 35 grams (under 1.2 ounces), while the largest species can reach up to 250 grams (about 9 ounces). This broad range reflects different ecological needs and metabolic rates within the group. The vole’s body is typically stout and compact, with short legs, contributing to a heavier, stockier appearance compared to a common mouse.
The tail is usually one-third to one-half the length of the head and body combined. For example, a vole with a 10-centimeter body might have a tail of only 3 to 5 centimeters. This short, often furred tail is a key factor in their identification and contrasts with the long, scaly tails found on true rats or house mice.
Key Species Driving Size Variation
The extremes of the size range are best illustrated by specific species, from the most diminutive to the largest known examples. One of the smallest is the Woodland Vole (Microtus pinetorum), commonly found in the eastern United States. This species is quite small, with a body length that often does not exceed 10 centimeters (4 inches) and a weight usually remaining under 35 grams (1 ounce).
The common Meadow Vole (Microtus pennsylvanicus) represents a mid-sized example, distributed widely across North America. Adults typically grow to a total length of 15 to 20 centimeters (6 to 8 inches), though their weight is relatively light, often less than 50 grams (under 2 ounces). A close relative, the Prairie Vole (Microtus ochrogaster), is similarly sized, weighing between 37 and 48 grams and ranging from 130 to 172 millimeters in total length.
At the upper end of the spectrum is the European Water Vole (Arvicola amphibius), which drives the maximum size for the group. This semi-aquatic rodent, found throughout Eurasia, is substantially larger and heavier than its North American cousins. It can reach a body length of up to 22 centimeters (9 inches), and large individuals can weigh as much as 250 grams (9 ounces), making it the giant of the Arvicolinae subfamily.
Vole Identification: Distinguishing Them from Mice and Shrews
Because of their size and general appearance, voles are frequently confused with house mice, deer mice, and shrews, but several physical details allow for accurate identification. A primary distinction lies in the tail: voles have a short, blunt tail that is conspicuously shorter than their body length and often covered in hair. In contrast, true mice, such as the common house mouse, possess a long, thin, and typically scaly tail that is roughly the same length as their head and body combined.
Voles also have a more robust, stocky build with a rounded, blunt snout, giving the head a less pointed profile. Their eyes and ears are relatively small and often partially concealed within their dense fur, unlike mice, which have noticeably larger, more prominent eyes and ears. These features contribute to the overall impression of a chubbier, more compact animal than the slender-bodied mouse.
Shrews are a different type of mammal, classified as insectivores rather than rodents, and are distinguished most easily by their head shape. Shrews have a notably elongated, pointed snout that tapers sharply, unlike the vole’s blunt face. Even the largest shrews lack the thick, rounded body shape of a vole, and their dental structure is entirely different, reflecting their carnivorous diet.