The answer to how many moles live together in a tunnel system is almost universally one, but with a few dramatic exceptions. Moles are small mammals, and their subterranean life has driven them toward a solitary existence in most species. While the typical mole is a fiercely independent creature, certain mole-rat species have evolved a complex social structure that allows hundreds of individuals to share a single, vast burrow network. This unique biology requires looking beyond the common European or Eastern mole to understand the full spectrum of subterranean cohabitation.
The Solitary Nature of Most Mole Species
The vast majority of mole species, such as the European mole and the Eastern mole, are solitary creatures that maintain an individual territory within their tunnel network. This existence is primarily driven by their extremely high metabolic rate, which necessitates a constant and reliable food supply. Moles are insectivores whose diet consists mainly of earthworms and other invertebrates, and they must consume an amount of food roughly equivalent to half their body weight every day.
The mole’s tunnel system is a sophisticated trap for their prey, and the resident mole must patrol and defend this resource against all rivals. Any other mole entering an established tunnel is viewed as a direct threat, leading to aggressive and often fatal territorial disputes. This behavior ensures that the food resources within a given area of soil are exclusively available to the single mole who maintains the tunnels.
This extreme territoriality is a direct consequence of the constant need to forage and maintain a food source. The defense of the burrow ensures a sufficient supply of earthworms, which the mole may paralyze and store in a dedicated cache within the deeper parts of the tunnel system. The single occupant is the sole beneficiary of this underground larder.
Anatomy of a Single Mole’s Tunnel System
The subterranean home of a solitary mole is a complex, multi-tiered structure exclusively maintained by its one occupant. The tunnels are categorized into two types based on their purpose and depth.
Shallow, temporary tunnels, known as feeding runs, are typically located one to twelve inches beneath the surface and appear as the characteristic raised ridges in a lawn. These runs are used for immediate foraging and are often abandoned after the local food supply has been depleted.
Deeper tunnels form the permanent infrastructure of the territory, serving as the main runways and travel routes. These main passageways can descend to depths of up to 40 inches. Located within this permanent network are specific functional chambers, including a nesting chamber, often lined with plant material for insulation. The deeper sections also contain specialized storage areas where the mole keeps its cache of paralyzed earthworms, all designed to support a single inhabitant.
The Eusocial Exception of Naked Mole Rats
A radical departure from the solitary rule is found in the Naked Mole Rat, a species that exhibits a highly complex social structure known as eusociality. This is a form of communal living previously observed almost exclusively in insects like ants and bees, where a single female is responsible for all reproduction. These colonies in the arid regions of East Africa typically average 70 to 80 individuals, with some containing nearly 300 members within a single system.
The colony is governed by a single breeding female, referred to as the Queen, who is the physically largest individual. She mates with a small number of reproductive males, and the rest of the colony is composed of non-breeding individuals who fill specialized roles. These non-reproductive mole rats function as different castes.
Specialized Castes
- Workers are responsible for digging new tunnels and gathering food.
- Soldiers are physically larger and defend the colony.
This communal effort allows them to excavate massive tunnel systems, with some networks reaching a total length of up to 2.5 miles. The eusocial structure is an adaptation to the harsh, patchy distribution of their food—large underground tubers. Unlike solitary moles, the Naked Mole Rat has a comparatively low metabolic rate and is poikilothermic, meaning it cannot effectively regulate its body temperature. They must rely on huddling together in large masses within the nest chamber to maintain warmth, cementing their collective lifestyle.
Temporary Cohabitation During Reproduction
For the typical solitary mole species, the only time cohabitation occurs is during a brief, seasonal reproductive window. In late winter or early spring, a male temporarily enters the territory of a female for mating. This interaction is short-lived, and the male departs once mating is complete, leaving the female alone to manage her territory and raise the litter.
The female gives birth to pups in her nesting chamber after a gestation period of approximately four to six weeks. The young moles remain within the safety of the mother’s burrow system for a relatively short duration. After about 30 to 36 days, the young are compelled to disperse from the mother’s territory to establish their own separate tunnel systems. This dispersal is a dangerous time, as the young often move above ground at night, making them vulnerable before they can establish a solitary territory.