Types of Fox Dens
Fox dens are of two types: generic, nonbreeding dens and breeding dens. The former mainly serve as resting places, while the main purpose of breeding dens is to house the raising of pups. Most dens are inhabited primarily during the winter months. Nonbreeding dens may be inhabited year-round. Many female foxes return to the same breeding dens each season.
Surrounding Habitat
Relatively lazy by habit, foxes often inhabit abandoned dens. These may include dens formerly occupied by squirrels, other foxes or groundhogs. When foxes build dens, they usually choose wooded areas, if possible. They also build dens in grasslands.
Water Access
Most fox dens are relatively close to a stream, lake or rain-filled water source. Naturalists looking for fox dens often can detect them by their urine smell.
Entrances, Drainage and Hills
Foxes design breeding dens differently from resting dens. Instead of one entrance, foxes typically have several in breeding dens, apparently for cubs to escape quickly when predators approach. Foxes seek den locations with excellent drainage to avoid the risk of flooding.
Red foxes often prefer hillside locations. Better drainage and the comparative ease of digging on hillsides may have induced this adaptation.