denning

Denning is the behavior by which some animals, particularly mammals, occupy a den—an enclosed shelter that can be an underground burrow, a hollow tree, a rock crevice, or another secluded structure—for shelter, reproduction, or hibernation. Dens may be seasonal or permanent, and they are often reused by individuals or family groups across years.

In many species, denning serves as a maternity site where females give birth and care for offspring in a protected environment before the young disperse. Dens also provide shelter from weather and predators and help conserve energy, especially during periods of scarcity or cold weather. Den sites are selected based on factors such as microclimate, concealment, proximity to food sources, and safety from disturbance. Some species excavate elaborate networks of entrances and chambers (setts) and may expand or abandon dens as needed.

Common denning animals include bears, foxes, badgers, and other canids, as well as some rodents and marsupials. Bears typically den in caves, excavated burrows, or snow-filled dens, entering after food stores are built and emerging in spring. Foxes and badgers maintain dens that may be used for many years and serve as both nurseries and refuges.

Human activities—such as development, forestry, or recreational disturbance—can disrupt denning and affect reproductive success. Protected areas and wildlife-management practices may designate and monitor den sites, and artificial or rehabilitative dens are sometimes used to aid populations.

See also: den, burrow, hibernation, maternity den.