The mole, a small subterranean mammal, spends its life creating an intricate network of tunnels. Within this system is a single, centralized structure known as the nest or “fortress.” This specialized chamber functions as the permanent living quarters, providing the most protected area for resting, shelter, and raising young.
The Physical Structure of the Nesting Chamber
The mole’s nest chamber is a carefully constructed underground space designed for stability and insulation. The chamber is typically spherical or circular, a shape that helps distribute the pressure of the surrounding soil. This permanent dwelling is an enlargement of the main tunnel, often measuring six to ten inches in diameter.
The interior is lined with soft, dry plant material collected from the surface. This bedding consists of dried grasses, root fibers, moss, and dead leaves. The material is densely packed to create a sturdy, protective layer that insulates the occupants from temperature fluctuations and moisture. This shelter ensures the survival of the single annual litter of three to seven pups born in the spring.
Location and Depth Within the Tunnel System
The nest location prioritizes security and environmental stability. It is situated deep within the soil profile, below the shallow tunnels used for daily foraging. The fortress chamber is typically found at a depth ranging from 12 to 24 inches below the surface. This depth protects the occupants from freezing temperatures in winter and excessive heat during summer. Moles often place the nest beneath large, protective structures.
Protective Structures
These structures include:
- Tree roots
- Paved walkways
- Boulders
- Fence rows
These overhead barriers add physical protection from predators and human disturbance, helping to maintain a stable environment. The chamber connects to the rest of the tunnel network via one or more main runways. These are deep, permanent travel routes that link the fortress to the shallower feeding grounds.
Differentiating the Nest from Mole Tunnels and Mounds
The permanent nesting chamber is rarely visible from the surface, unlike the common signs of mole activity. The most common sign is the surface run, a shallow tunnel created just beneath the lawn, appearing as a raised ridge. These are temporary feeding tunnels used to hunt for earthworms and insect larvae near the surface.
The main indicator of deeper activity is the molehill, a conical mound of soil pushed to the surface. Unlike gopher mounds, a molehill lacks a central, open entrance hole because the mole pushes excavated dirt up through a vertical shaft. These mounds signify the construction or maintenance of the deep main runways that lead to the permanent parts of the system, including the hidden fortress.