Octodon degus
degu

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, Torres-Mura, and Yanez, 1987; Woods and Boraker, 1975)

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, Torres-Mura, and Yanez, 1987; Fulk, 1976)

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)

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

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)

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)

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)

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, Veloso, and Bozinovic, 1999; Veloso and Kenagy, 2005; Woods and Boraker, 1975)

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)

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)

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)

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)

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)