An at the entrance of its burrow">Eastern chipmunk at the entrance of its burrow
A burrow is a hole or tunnel excavated into the ground by an
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
to construct a space suitable for habitation or temporary refuge, or as a byproduct of
locomotion. Burrows provide a form of shelter against
predation
Predation is a biological interaction
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or o ...
and exposure to the elements, and can be found in nearly every
biome
A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
and among various
biological interaction
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species ( interspecific interactio ...
s. Many animal species are known to form burrows. These species range from small
invertebrates
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
, such as the ''
Corophium arenarium'', to very large
vertebrate
Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...
species such as the
polar bear. Burrows can be constructed into a wide variety of substrates and can range in complexity from a simple tube a few centimeters long to a complex network of interconnecting tunnels and chambers hundreds or thousands of meters in total length; an example of the latter level of complexity, a well-developed burrow, would be a
rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit s ...
warren.
Vertebrate burrows
A large variety of vertebrates construct or use burrows in many types of substrate; burrows can range widely in complexity. Some examples of vertebrate burrowing animals include a number of
mammals,
amphibians,
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...
(
dragonet and
lungfish),
reptiles, and
birds
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
(including small
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s
).
Mammals are perhaps most well known for burrowing. Mammal species such as
Insectivora like the
mole, and
rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are roden ...
s like the
gopher,
great gerbil and
groundhog are often found to form burrows. Some other mammals that are known to burrow are the
platypus,
pangolin,
pygmy rabbit,
armadillo,
rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...
and
weasel.
The
rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit s ...
, a member of the family
Lagomorpha, is a well-known burrower. Some species such as the groundhog can construct burrows that occupy a full cubic metre, displacing about of dirt. There is evidence that rodents may construct the most complex burrows of all vertebrate burrowing species.
For example,
great gerbils live in family groups in extensive burrows, which can be seen on satellite images. Even the unoccupied burrows can remain visible in the landscape for years. The burrows are distributed regularly, although the occupied burrows appear to be clustered in space. Even
Carnivora like the
meerkat, and
marsupials, such as
wombats are burrowers. The largest burrowing animal is probably the
polar bear when it makes its
maternity den in snow or earth.
Lizards are also known to construct and live in burrows, and may exhibit territorial behaviour over the burrows as well. There is also evidence that a burrow provides protection for the
Adelaide pygmy blue-tongue skink (''Tiliqua adelaidensis'') when fighting, as they may fight from inside their burrows.
Burrows by birds are usually made in soft soils; some
penguins and other
pelagic seabirds are noted for such burrows. The
Magellanic penguin is an example, constructing burrows along coastal
Patagonian regions of
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
and
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
.
[C. Michael Hogan, (2008]
''Magellanic penguin'', Globaltwitcher.com, ed. Nicklas Stromberg
/ref> Other burrowing birds are puffins, kingfisher
Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania ...
s, and bee-eaters
The bee-eaters are a group of non-passerine birds in the family Meropidae, containing three genera and thirty species. Most species are found in Africa and Asia, with a few in southern Europe, Australia, and New Guinea. They are characterised b ...
.
Kangaroo mice
A kangaroo mouse is either one of the two species of jumping mouse ( genus ''Microdipodops'') native to the deserts of the southwestern United States, predominantly found in the state of Nevada. The name " kangaroo mouse" refers to the species' ...
construct burrows in fine sand.
Invertebrate burrows
Scabies mites construct their burrows in the skin of the infested animal or human. Termite
Termites are small insects that live in colonies and have distinct castes ( eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blat ...
s and some wasps construct burrows in the soil and wood. Ants construct burrows in the soil. Some sea urchins and clams can burrow into rock.
The burrows produced by invertebrate animals can be filled actively or passively. Dwelling burrows which remain open during the occupation by an organism are filled passively, by gravity rather than by the organism. Actively filled burrows, on the other hand, are filled with material by the burrowing organism itself.
The establishment of an invertebrate burrow often involves the soaking of surrounding sediment in mucus to prevent collapse and to seal off water flow.
Examples of burrowing invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s are insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
s, spiders, sea urchins, crustaceans, clams and worms.
Excavators, modifiers, and occupants
Burrowing animals can be divided into three categories: primary excavators, secondary modifiers and simple occupants. Primary excavators are the animals that originally dig and construct the burrow, and are generally very strong. Some animals considered to be primary excavators are the prairie dog and the aardvark. Pygmy gerbil
The pygmy gerbil (''Gerbillus henleyi'') is distributed mainly in Algeria to Israel and the Arabian Peninsula
The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , " ...
s are an example of secondary modifiers, as they do not build an original burrow, but will live inside a burrow made by other animals and improve or change some aspects of the burrow for their own purpose. The third category, simple occupants, neither build nor modify the burrow but simply live inside or use it for their own purpose. Some species of bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
make use of burrows built by tortoises, which is an example of simple occupancy. These animals can also be referred to as commensals.
Protection
Some species may spend the majority of their days inside a burrow, indicating it must have good conditions and provide some benefit to the animal. Burrows may be used by certain species as protection from harsh conditions, or from predators. Burrows may be found facing the direction of sunlight or away from the direction of cold wind. This could help with heat retention and insulation, providing protection from temperatures and conditions outside. Insects such as the earwig may construct burrows to live in during winter, and use them for physical protection. Some species will also use burrows to store and protect food. This provides a benefit to the animal as it can keep food away from other competition. It also allows the animal to keep a good stock of food inside the burrow to avoid extreme weather conditions or seasons where certain food sources may be unavailable. Additionally, burrows can provide protection to animals that have just had their young, providing good conditions and safety for vulnerable newborn animals. Burrows may also provide shelter to animals residing in areas frequently destroyed by fire, as animals deep underground in a burrow may be kept dry, safe and at a stable temperature.
Fossil burrows
Burrows are also commonly preserved in the fossil record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
as burrow fossil
Burrow fossils are the remains of burrows - holes or tunnels excavated into the ground or seafloor - by animals to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion preserved in the rock record. Because bu ...
s, a type of trace fossil.
See also
* Holt
* Maternity den
* Sett - a network of badger tunnels.
* Spreite
* Subterranean fauna
* Communal burrow
References
{{Subterranea
Ethology
Shelters built or used by animals
de:Behausung#Tierische Behausungen