Wallowing in animals is comfort behaviour during which an animal rolls about or lies in

mud A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

. Some definitions include rolling about in dust, however, in

ethology Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objectiv ...

this is usually referred to as

dust bathing Dust bathing (also called sand bathing) is an animal behavior characterized by rolling or moving around in dust, dry earth or sand, with the likely purpose of removing parasites from fur, feathers or skin. Dust bathing is a maintenance behavior ...

. Wallowing is often combined with other behaviours to fulfill its purpose; for example, elephants will often blow dirt over themselves after wallowing to create a thicker "coating", or pigs will allow the mud to dry before rubbing themselves on a tree or rock to remove ectoparasites stuck in the mud.

Functions

Nolan warthog (Phacochoerus africanus africanus) in mud

Many functions of wallowing have been proposed although not all have been tested by rigorous scientific investigation. Proposed functions include: *Thermoregulation –

domestic pigs The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...

(''Sus scrofa''), great Indian rhinoceros (''Rhinoceros unicornis''),

warthogs ''Phacochoerus'' is a genus in the family Suidae, commonly known as warthogs (pronounced ''wart-hog''). They are pigs who live in open and semi-open habitats, even in quite arid regions, in sub-Saharan Africa. The two species were formerly cons ...

(''Phacochoerus aethiopicus''),

elephants Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and ...

(family Elephantidae) *Providing a sunscreen – pigs, warthogs, elephants *Male-male conflict social behaviour –

wapiti The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...

(''Cervus elaphus''), European bison (''Bison bonasus''), deer *Removal of ectoparasites – white rhinoceros (''Ceratotherium simum''), American bison (''Bison bison''), warthog *Social cohesion – American bison *Relief from

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

– European bison, elephant seals (genus ''Mirounga'') *Relief from biting insects – tamaraw (''Bubalus mindorensis''), American bison, tapirs (''Tapirus bairdii''), warthog, elephants *Play in young animals – American bison *Skin maintenance (preventing dehydration) – hippopotamus (''Hippopotamus amphibius'') *Camouflage – warthog * Scent-marking – Some animals urinate in a wallow before entering and rolling in it, presumably as a form of scent-marking behaviour *Skin microbiome selection – Horses

Domestic pigs

Pigs lack functional sweat glands and are almost incapable of panting. To thermoregulate, they rely on wallowing in water or mud to cool the body. Adult pigs under natural or free-range conditions can often be seen to wallow when air temperature exceeds 20 °C. Mud is the preferred substrate; after wallowing, the wet mud provides a cooling, and probably protecting, layer on the body. When pigs enter a wallow, they normally dig and root in the mud before entering with the fore-body first. They then wriggle the body back and forth, and rub their faces in the mud so all of the body surface is covered. Before they leave the wallow, they often shake their heads and body, often finishing with rubbing against a tree or a stone next to the wallow. When indoors and hot, domestic pigs often attempt to wallow on wet floor surfaces and in the dunging areas. Although temperature regulation seems to be the main motivation for wallowing in pigs, they will still wallow in colder weather. While many have suggested that pigs wallow in mud because of a lack of sweat glands, pigs and other wallowing animals may have not evolved functional sweat glands because wallowing was a part of their behavioural repertoire.Bracke, M. (2011)
Review of wallowing in pigs: Description of the behaviour and its motivational basis
Applied Animal Behaviour Science, 132: 1-13 Pigs are genetically related to animals such as

hippopotamus The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extan ...

and

whales Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

. It has been argued that wallowing behaviour and the desire to be in shallow, murky water could have been a step to the evolution of whales and other marine mammals from land-dwelling mammals.

Sumatran rhinoceros

The Sumatran rhino (''Dicerorhinus Sumatrensis'') spends a large part of its day wallowing. When mud holes are unavailable, the rhino will deepen puddles with its feet and horns. One 20-month study of wallowing behaviour found they will visit no more than three wallows at any given time. After two to 12 weeks using a particular wallow, the rhino will abandon it. Typically, the rhino will wallow around midday for two to three hours at a time before foraging for food. Although in zoos the Sumatran rhino has been observed wallowing less than 45 minutes a day, the study of wild animals found 80–300 minutes per day spent in wallows. Captive individuals deprived of adequate wallowing have quickly developed broken and inflamed skins, suppurations, eye problems, inflamed nails, hair loss and have eventually died.

Deer

Many deer perform wallowing, creating wallow sites in wet depressions in the ground, eventually forming quite large sites (2–3 m across and up to 1 m deep). However, it has been claimed that only some species of deer wallow;

red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...

(''Cervus elaphus'') particularly like to wallow but fallow deer (''Dama dama''), for example, do not wallow. Even within the red deer species, there is variation between sub-species and breeds in wallowing behaviour. For example, although wapiti do wallow, they and crossbreds are less inclined to wallow than European red deer.

References

External links