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Octodon degusdegu

By Mary Hejna

Geographic Range

Octodon degus is generally considered endemic to west central Chile, where it inhabits the lower slopes of the Andes. Although some have argued that its range may extend north into Peru, this is not well supported. It is common in the international pet trade, however, and is often used in laboratory studies outside of its native range. (Contreras, et al., 1987; Woods and Boraker, 1975)

Habitat

Octodon degus inhabits a mediterranean-type semi-arid shrubland ecosystem called "matorral", which is found on the western slopes of the Andes between 28 and 35 degrees south latitude. Further north the climate becomes too arid to support this plant community, and further south it is too wet. Degus appear to be limited to elevations below 1200 meters, both by the distribution of their habitat and by their intolerance of low oxygen partial pressure. Degus are well able to inhabit lands influenced by cattle grazing, and are agricultural pests in some areas. (Contreras, et al., 1987; Fulk, 1976)

  • Range elevation
    0 to 1200 m
    0.00 to 3937.01 ft

Physical Description

Octodon degus superficially resembles a gerbil, but is much larger. Degus typically weigh between 170 and 300 g, and measure between 325 and 440 mm in length, including the tail. The fur is yellow-brown on the back and head, and the underparts and feet are cream colored. There is a pale band around the eye and, in some individuals, the neck. The tail is moderately long and conspicuously tufted. The ears are large and darkly pigmented. The fifth digit is reduced, and on the forefeet it has a nail instead of a claw. The cheekteeth are hypsodont and their biting surfaces resemble a figure of eight. Sexes are difficult to distinguish, but males tend to be about 10% larger than females. Pups are born furred and able to see, and begin exploring within hours of birth. Octodon degus can be distinguished from the two other members of the genus Octodon by slight differences in dental morphology. It is also smaller than its relatives and its tail is said to be more noticeably tufted. (Fulk, 1976; Lee, 2004)

  • Sexual Dimorphism
  • male larger
  • Range mass
    170 to 300 g
    5.99 to 10.57 oz
  • Range length
    325 to 440 mm
    12.80 to 17.32 in
  • Average basal metabolic rate
    0.958 W
    AnAge

Reproduction

During the annual breeding season, male-male aggression temporarily increases. Males exclude other males from their burrow and monopolize the females (usually 2 to 4) who live there. Dustbathing and urine marking may be used in the defense of territory by both sexes, but these behaviors particularly increase in the male during the breeding season. Courting males often engage in mutual grooming with females, and frequently perform a courtship ritual which involves wagging of the tail and trembling of the body. The male then raises a hind leg and sprays urine onto the female. This may serve to familiarize her with his scent and perhaps make her more receptive to his advances in the future. Receptive females may sometimes enurinate males in a similar fashion. Related female degus may nurse each other's young. (Ebensperger and Caiozzi, 2002; Fulk, 1976; Kleiman, 1974; Soto-Gamboa, 2005)

In the wild degus tend to breed once per year. The breeding season usually begins in late May (autumn in Chile), and the young are conceived in late winter to early spring (September to October). In wet years, degus may produce second litters. It has been suggested that degus may be induced ovulators, but this has not been established for certain. There is also some evidence that male reproductive organs may be sensitive to changes in photoperiod. The gestation period is 90 days, and litter size is typically 4-6 pups. The young are precocial. They are born with fur and teeth; their eyes are open and they are able to move about the nest on their own. Pups are weaned at 4 to 5 weeks, and become sexually mature between 12 and 16 weeks of age. Degus do not reach adult size until about 6 months of age, however, and they generally live in same-sex social groups until they are about 9 months old and their first breeding season occurs. It has been reported that pups raised in isolation in the laboratory experience severe neural and behavioral abnormalities. (Ebensperger and Hurtado, 2005; Lee, 2004; Woods and Boraker, 1975)

  • Breeding interval
    Degus breed once a year.
  • Breeding season
    Wild degus breed in September and October.
  • Range number of offspring
    4 to 6
  • Average number of offspring
    6
    AnAge
  • Range gestation period
    90 to 95 days
  • Range weaning age
    4 to 6 weeks
  • Range time to independence
    4 to 6 weeks
  • Range age at sexual or reproductive maturity (female)
    12 to 16 weeks
  • Range age at sexual or reproductive maturity (male)
    16 (high) weeks

Before conception can occur, the male degu must invest considerable energy in the defense of his territory and harem from other males. The female subsequently expends considerable energy in gestation and lactation. The pregnancy is relatively long for a rodent, and the young are born well developed. After birth, both parents protect and provision the pups. Degus nest communally, and groups of related females nurse one another's young. In the laboratory, the female remains close to the pups until two weeks after birth, and males have been observed to huddle with the young during this period without instances of infanticide. In the wild, male degus may spend as much time feeding and huddling with the young as females do. Pups begin to eat solid food at about two weeks of age, and venture out of the burrow at three weeks. Upon weaning at four to six weeks, the pups are able to live independently of the parents and form same-sex social groups until their first breeding season. (Ebensperger and Hurtado, 2005; Fulk, 1976; Lee, 2004; Woods and Boraker, 1975)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • protecting
      • male
      • female

Lifespan/Longevity

In laboratory conditions, degus typically live five to eight years.

  • Typical lifespan
    Status: captivity
    5 to 8 years

Behavior

Degus are social and tend to live in groups of one to two males and two to five related females. Females participate in rearing on another's young. Groups maintain territories throughout much of the year. Degus are semi-fossorial, digging extensive communal burrow systems. These burrows are often shared by Bennett's chinchilla rat (Abrocoma bennettii). Degus feed exclusively above ground, however, and have been observed climbing into the low branches of shrubs while foraging. Dustbathing is an important social behavior among degus. Groups repeatedly mark favorite wallows with urine and anal gland secretions. This may help the group identify each other by scent as well as delineating territorial boundaries. Degus are mainly diurnal, and are most active during the morning and evening. (Ebensperger, et al., 2004; Fulk, 1976; Woods and Boraker, 1975)

  • Average territory size
    200 m^2

Home Range

Fulk (1976) estimated that social groups of degus occupy home areas of roughly 200 square meters, and that their density is about 75 degus per hectare. This may be an underestimate, however, due to the trapping methods used. (Fulk, 1976)

Communication and Perception

Degus have well-developed sight, smell, and hearing. They are highly vocal and use various calls to communicate with one another, including alarm calls, mating calls, and communication between parents and young. Vision is very important in avoidance of predators and in foraging. It has been shown that degus are able to see ultraviolet wavelengths, and that their urine reflects in the UV range when fresh. It has therefore been suggested that degus' urine scent marks are also visual cues. These scent marks are also used as dust wallows, allowing members of a social group to identify each other by scent. (Chavez, et al., 2003; Fulk, 1976; Woods and Boraker, 1975)

Food Habits

Degus are generalist herbivores. They feed on the leaves, bark, and seeds of shrubs and forbs. Among their favorite foods are the bark of Cestrum palqui and Mimosa cavenia, leaves and bark of Proustia cuneifolia, Atriplex repunda, and Acacia caven, annuals such as Erodium cicutarum when in season, green grasses, and thistle seeds. Degus choose food items that reduce fiber and increase nitrogen and moisture in the diet, and thus prefer young leaves and avoid woodier shrubs. Degus rely on microbial fermentation in their enlarged cecum (they are "hindgut fermenters") to digest their food. They reingest a large percentage of their feces, usually during the night. This allows them to maximize their digestion. Degus store food in the winter, and it has been reported that they occasionally eat meat in old age. (Gutierrez and Bozinovic, 1998; Kenagy, et al., 1999; Veloso and Kenagy, 2005; Woods and Boraker, 1975)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • Other Foods
  • dung

Predation

Octodon degus is subject to predation by larger mammals such as culpeo foxes (Lycalopex culpaeus), and from the air by raptors such as barn owls (Tyto alba), short-eared owls (Asio flammeus), and black-chested buzzard eagles (Geranoaetus melanoleucus). Degus use vigilance and cover to avoid predators. Their pelage is also counter-shaded and matches the soil color, which reduces visibility to predators. Degus live socially and use alarm calls to warn others of danger. When a predator is spotted, they take cover in shrubby areas and may retreat to the communal burrow. (Ebensperger and Wallem, 2002; Woods and Boraker, 1975)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Octodon degus affects the plant community in its habitat by selective browsing. Degus behaviorally reduce the fiber content of their diet, preferrentially eating shrubs such as Adesmia bedwellii, Baccharis paniculata, and Chenopodium petioare, which are less fibrous and less thorny than others. These species have been shown to increase their foliage area upon exclusion of degus. As degus are very common, they are themselves an important food source for their predators. (Gutierrez and Bozinovic, 1998)

Degus often live in association with Bennett's chinchilla rats (Abrocoma bennettii). The two species are known to share burrow systems and have even been observed in the same chamber within a burrow. This is believed to be a mutualistic relationship, but it is not well understood. (Fulk, 1976; Woods and Boraker, 1975)

  • Ecosystem Impact
  • creates habitat
Mutualist Species
  • Abrocoma benettii (Bennett's chinchilla rat)

Economic Importance for Humans: Positive

Degus are frequently kept as pets, and are used extensively in laboratory research. Because they are largely diurnal, they are useful in research on circadian rhythms, and their intolerance of sugars makes them ideal models for diabetes research. (Lee, 2004)

  • Positive Impacts
  • pet trade
  • research and education

Economic Importance for Humans: Negative

Degus are significant agricultural pests in some areas. They take advantage of cultivated prickly pear cactus, wheat, vineyards, and orchards as abundant food sources, and can do considerable damage. They are also known to host three species of parasites that can infect humans. (Fulk, 1976)

  • Negative Impacts
  • injures humans
    • carries human disease
  • crop pest

Conservation Status

Octodon degus is considered the most common mammal in its range, and is not considered threatened or endangered. (Ebensperger and Wallem, 2002; Woods and Boraker, 1975)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Mary Hejna (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

cooperative breeder

helpers provide assistance in raising young that are not their own

coprophage

an animal that mainly eats the dung of other animals

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynous

having more than one female as a mate at one time

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born

References

Chavez, A., F. Bozinovic, L. Peichl, A. Palacios. 2003. Retinal spectral sensitivity, fur coloration, and urine reflectance in the genus Octodon (Rodentia): implications for visual ecology. Investigative Opthalmology & Visual Science, 44/5: 2290-2296.

Contreras, L., J. Torres-Mura, J. Yanez. 1987. Biogeography of Octodontid rodents: An eco-evolutionary hypothesis. Fieldiana: Zoology, New Series, 39: 401-411.

Ebensperger, L., F. Bozinovic. 2000. Energetics and burrowing behaviour in the semifossorial degu Octadon degus (Rodentia: Octodontidae). Journal of Zoology, 252: 179-186.

Ebensperger, L., A. Caiozzi. 2002. Male degus, Octodon degus, modify their dustbathing behavior in response to social familiarity of previous dustbathing marks. Revista Chilena de Historia Natural, 75: 157-163.

Ebensperger, L., M. Hurtado. 2005. On the relationship between herbaceous cover and vigilance activity of degus (Octodon degus). Ethology, 111/6: 593-608.

Ebensperger, L., M. Hurtado. 2005. Seasonal changes in the time budget of degus, Octadon degus.. Behaviour, 142: 91-112.

Ebensperger, L., M. Hurtado, M. Soto-Gamboa, E. Lacey, A. Chang. 2004. Communal nesting and kinship in degus (Octodon degus). Naturwissenschaften, 91: 391-395.

Ebensperger, L., P. Wallem. 2002. Grouping increases the ability of the social rodent, Octodon degus, to detect predators when using exposed microhabitats. Oikos, 98: 491-497.

Fulk, G. 1976. Notes on the activity, reproduction, and social behavior of Octodon degus. Journal of Mammalogy, 57/3: 495-505.

Gutierrez, J., F. Bozinovic. 1998. Diet selection in captivity by a generalist herbivorous rodent (Octodon degus) from the Chilean coastal desert. Journal of Arid Environments, 39: 601-607.

Kenagy, G., R. Nespolo, R. Vasquez, F. Bozinovic. 2002. Daily and seasonal limits of time and temperature to activity of degus. Revista Chilena de Historia Natural, 75: 567-581.

Kenagy, G., C. Veloso, F. Bozinovic. 1999. Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy. Physiological and Biochemical Zoology, 72/1: 78-86.

Kleiman, D. 1974. Patterns of behaviour in hystricomorph rodents. Symposium of the Zoological Society (London), 34: 171-209.

Lee, T. 2004. Octodon degus: A diurnal, social, and long-lived rodent. ILAR Journal, 45/1: 14-24.

Soto-Gamboa, M., M. Villalon, F. Bozinovic. 2005. Social cues and hormone levels in male Octadon degus (Rodentia): a field test of the Challange Hypothesis. Hormones and Behavior, 47/3: 311-318.

Soto-Gamboa, M. 2005. Free and total testosterone levels in field males of Octodon degus (Rodentia, Octodontidae): accuracy of the hormonal regulation of behavior. Revista Chilena de Historia Natural, 78/2: 229-238.

Tokimoto, N., K. Okanoya. 2004. Spontaneous construction of "Chines boxes" by Degus (Octodon degus): A rudiment of recursive intelligence?. Japanese Psychological Research, 46/3: 255-261.

Veloso, C., G. Kenagy. 2005. Temporal dynamics of milk composition of the precocial caviomorph Octodon degus (Rodentia : Octodontidae). Revista Chilena de Historia Natural, 78/2: 247-252.

Woods, C., D. Boraker. 1975. Octodon degus. Mammalian Species, 67: 1-5.

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