Finding an unexpectedly large hole in the ground often sparks curiosity about the identity of the subterranean architect. A “big hole” is generally one measuring more than four or five inches in diameter, excluding tunnels created by small rodents and insects. Identifying the occupant requires an investigative approach, focusing on the size, shape, and surrounding debris left behind. Understanding the purpose behind the excavation is key to correctly identifying the animal responsible.
Why Animals Excavate Large Structures
Animals invest significant energy into digging large underground structures because these spaces provide a high return on survival and reproductive success. These structures fulfill specific biological needs that cannot be met above ground, primarily obtaining shelter from extreme weather like heat, cold, or heavy rain.
The size of the hole is often proportional to the size of the animal and the specific function the space serves. Large excavations accommodate maternity dens, which must be spacious enough to house a litter of young and nesting material. Other large burrows serve as secure, temperature-stable locations for long-term dormancy, such as hibernation or aestivation during dry periods.
Identification Clues: Size, Shape, and Soil Piles
The physical evidence left at the site provides data for identifying the occupant. The most obvious indicator is the hole’s diameter, which estimates the animal’s body size. Entrances measuring 8 to 12 inches typically suggest a medium-sized mammal, such as a groundhog or a fox, while holes wider than 12 inches might point to a badger or coyote.
The angle of the entrance is another telling feature, with some species preferring a gradual slope while others drop nearly straight down. A gently sloping entrance is easier for a larger animal to navigate, while a more vertical entrance acts as an immediate defense against surface predators.
The arrangement of the excavated soil, known as the spoil, is a distinctive clue. Some animals push soil out in a large, fan-shaped apron next to the entrance, indicating powerful digging. Other species scatter the dirt widely as they kick it out, resulting in a less defined mound. Tracks or claw marks in the loose soil can further narrow the possibilities.
Profiles of the Most Common Large-Hole Diggers
The groundhog, or woodchuck, is a common medium-sized excavator, constructing holes typically 8 to 12 inches in diameter. Their burrows are distinguished by a large, semicircular mound of fresh dirt pushed out in a fan shape below a sloping entrance. Groundhogs often have several entrances, though only the main one features the large dirt apron.
Badgers are powerful diggers that create wider-than-tall, oval entrances, reflecting their broad bodies. The holes are typically 10 to 14 inches across and feature a significant pile of excavated soil. Badgers use strong forelimbs and long claws to pursue prey, resulting in heavily worked holes often showing scratch marks in the surrounding soil.
Coyotes and foxes also excavate large dens, particularly when raising pups. Their entrances are usually 10 to 15 inches wide and are often situated on slopes or under cover, such as the base of a tree. Fox dens are frequently identified by the presence of scat, food remains, or a musky odor nearby. Skunks are less specialized diggers but sometimes enlarge existing holes or dig shallow dens about 6 to 8 inches in diameter.
Distinguishing Between Permanent Dens and Temporary Burrows
A primary distinction in hole structure lies between a permanent residence, known as a den, and a temporary feeding tunnel or shelter. Permanent dens are designed for long-term occupancy and are generally wider and deeper to accommodate nesting material and the movements of a family unit. These structures are maintained and often feature complex, multi-entrance systems that allow for escape routes and ventilation.
Signs of frequent use, such as worn, flattened paths leading away from the entrance, characterize a permanent den. The ground around the opening may be bare from repeated friction, and there might be evidence of scat or discarded prey remains nearby. Conversely, a temporary burrow, often dug for immediate retreat or pursuing prey, is typically a simpler, less maintained tunnel. These temporary holes generally lack the multiple exits and heavy wear patterns seen at the entrance of a den.