Degu

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Degu
Octodon degus
Octodon degus
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Octodontidae
Genus: Octodon
Species: O. degus
Binomial name
Octodon degus
(Molina, 1782)

The Degu (Octodon degus) is a small caviomorph rodent that is native to Chile. It is sometimes referred to as the Brush-Tailed Rat (although not closely related to the rat family) and is also called the Common Degu, to distinguish it from the other members of the genus Octodon. Other members are also called degus, but they are distinguished by additional names. The name "degu" on its own, however, indicates either the genus Octodon or, more usually, O. degus. Degus are closely related to the chinchilla and guinea pig, also placed in parvorder Caviomorpha.

Contents

[edit] Social behavior

Degus are highly social. They live in burrows, and, by digging communally, they are able to construct larger and more elaborate burrows than they could on their own. Degus digging together co-ordinate their activities, forming digging chains. Females living in the same group have been shown to spontaneously nest communally; they nurse one another's young. They spend a large amount of time on the surface, where they forage for food. When foraging, their ability to detect predators is increased in larger groups, and each animal needs to spend less time in vigilance. Degus exhibit a wide array of communication techniques. They have an elaborate vocal repertoire, and the young need to be able to hear their mother's calls if the emotional systems in their brains are to develop properly. They use their urine to scent mark, and experiments have shown that they react to one another's marks.

Degus are seasonal breeders; the breeding season for wild degus begins in the Chilean winter, with pups born mid-late spring. It is also speculated that female degus are induced ovulators. Female degus are pregnant for approximately ninety days, having a relatively long gestation period compared to other rodents. Litters usually contain four to seven pups, but size can range from one or two up to fifteen young. Degu pups are born relatively precocial, fully furred and with eyes open, and their auditory and visual systems are functional at birth.

Unlike other octodontids, degus are diurnal, and they have good vision. Their retinas include rod cells and two types of cone cell, one of which has its peak sensitivity in the ultraviolet region of the spectrum. Behavioral experiments have shown that degus are able to discriminate ultraviolet light from the wavelengths visible to humans. It is likely that this ultraviolet sensitivity has a social function, since both their ventral (stomach) fur and their urine are highly UV reflective.

[edit] Diet

Degus are herbivores, feeding on grasses and browsing the leaves of shrubs, though they will also take seeds. Their feeding rate is constrained by the rate at which they can digest this relatively low quality food, and this varies between food types and environmental conditions, and like some other herbivores such as rabbits, they show coprophagy, chewing their own feces so as to extract more nutrition from them. This also serves to maintain healthy gut function during times when food is scarce. Although they are active by day, in high summer they do not leave their burrows in the middle of the day, and in hot conditions they forage as quickly as possible instead of maximising the quality of their food. They tend to forage in shaded areas, though this tendency is reduced in the absence of predators. In open areas they spend more time being vigilant, so their effectiveness as foragers is reduced. Degus have a significant impact on the vegetation in areas where they live, and as the only rodent foraging by day, their numbers influence the food supply available to the more numerous nocturnal rodents. However, numbers of all species of degu have been declining over recent decades, most likely due to human disturbance. Degus should never be fed on anything which contains sugar because due to a lack of sugar in their diet, it will cause diabetes to develop.

Degu after dust bath
Degu after dust bath

[edit] Role in human affairs

Degus are prone to diabetes due to their divergent insulin structure. For this reason they are used frequently for research in this field. The degu's popularity as a pet was influenced by this research, as animals were imported into various countries for research and study.

Degus are also used extensively as laboratory animals.[1] Neuroscientists at the Riken Institute in Tokyo, Japan, used degus in research on tool-using in animals with good eye-and-paw coordination, in which the rodents were trained over a period of two months to use a tiny rake to retrieve out-of-reach seeds.[2]

Degus have become popular as pets, though until very recently they were seldom found in pet shops. Their advantages over traditional small pets are their diurnal habits, bubbly personalities, the haired tail (as compared to rats and mice) and their lifetime: they are said to live up to 13 years under ideal circumstances (though a poor gene pool/genetic background often reduces a pet degu's lifespan significantly). The average lifespan of a degu in captivity is said to be around 5-8 years of age. One disadvantage of the degu as a pet is that they gnaw much more than most other common rodent pets, especially through plastic-bottomed cages typically found in pet stores. Untame degus, as with most small animals, can be prone to biting, but their intelligence makes them easy to tame. Degus often 'groom' their human owners, by a gentle nibbling action, but they can give a defensive bite if they feel threatened.

[edit] Keeping degus

Degu cuddle pile
Degu cuddle pile

Degus relate well to humans, but due to their highly social nature it is far better for their welfare to keep them in same-sex pairs or more. Two or more males may be kept together, provided they have been housed together from an early age. Keeping degus in pairs is very popular; degus bond strongly with other members of their 'group' and this is often extended to include humans who spend a lot of time around them. Degus should be kept in large roomy cages with lots of frequently changed straw and sawdust, for the animal to dig in. Hay should be provided freely as this helps to keep their digestive system healthy, and enables foraging behaviour. Plastic-bottomed cages will often be destroyed due to gnawing (although this can sometimes be avoided by supplying other materials for chewing) so housing degu in all-metal cages is required. Also, because of their gnawing nature, plastic toys and other objects must be kept out of a degu's reach, because some plastics contain components such as plasticizers that are toxic when ingested. Finally, the social nature of the degu can make them lonely, so humans keeping single specimens should take care to talk to their pet a lot, place the animal where it can take part in daily life of the household, and get them frequently out of the cage (degus like cuddling with humans, and can sit still and even sleep on laps if comfortable, but shouldn't be left running freely). The recent upsurge in interest in the degu as a pet has had both positive and negative results. The increase in popularity has created an increased awareness of the needs of degus as unique rodent companions, but there is also an increase in the amount of degus being put up for adoption because of ignorant or unsuspecting owners unable to care for them properly.

When keeping as a pet it is very important that their diet is strict; degus cannot be fed a sugary diet as they are prone to diabetes, and some woods can poison them. Captive degus can be fed twice a day with a 5g spoonful of either guinea pig mix/pellets or chinchilla pellets, or a mixture of both (care should be taken to check feeds do not contain molasses- a sugary substance). See external links below for a good formulated diet. Rabbit feed or pellets is not suitable for degus since it does not contain added vitamin C, which it is thought degu require, and often contains coccidiostats which are toxic to degus. Hay should be provided as needed due to the high fibre requirements of this species. Also degus enjoy gnawing on fresh broccoli, carrots, and the hard center core of romaine or other lettuce (except iceberg). Degus also enjoy tomatoes and cucumber peelings. When feeding produce be sure to thoroughly wash it off; and in addition scrub cucumber skins to remove any wax or other coatings.

For some degus feeding them with separate food dishes is a good idea as they tend to squabble and fight over their food. As with most small animals, fresh drinking water should be provided daily in their water bowl or drinking bottle. It is worth noting that even if food dishes are empty it does not mean the degu ate everything; they like to bury the food and store it. If your degus are doing this it is a good indicator they are being over fed[1].

Degus have continuously growing incisor and molar teeth and therefore should be provided with plenty of materials to chew/gnaw. If degus cannot grind their teeth, they can grow too much and the animal would not be able to eat anything at all. Apple and hazel woods are non-toxic for degus and help them with tooth wear[2]. Occasionally, give them calcium blocks, which you can buy in pet shops and add to them in order to pass the necessary calcium, phosphor and iron (mainly nursing females need calcium) to the animals[3].

Also, very much like their larger cousin the chinchilla, degus require regular dust baths to keep their coat free from oils and allow them to express related behaviors. You can use the same product as you would a chinchilla, most commonly the absorbent clay sepiolite.

Degus are diurnal by nature, although they express crepuscular patterns, tending to be more active in the morning and evening. This relates to their wild activity patterns, where it is often too hot for them to forage during mid-day in their native habitat. However, degus are known to be able to invert their circadian rhythms and become nocturnal in certain situations (but this is easily reverted).

Some degu owners supplement their degus with calcium and/or vitamin C supplements in their drinking water[4]. However, it has not yet been conclusively proven that degus require dietary vitamin C, and such supplements are prone to deteriorate rapidly in suspension so the dose each degu receives is unknown. It is advised to consult your veterinarian about mineral supplements for your degu.

It must be noted that a degu should never be grabbed or lifted by its tail. Like some lizards, a degu's tail can come off if grabbed. Unlike some lizards, it does not grow back and can permanently affect their balance.

[edit] Taxonomic issues

It has been suggested that the family Octodontidae, to which the degu belongs, should be reclassified into the order Lagomorpha (rabbits, hares and pikas). However recent studies in molecular systematics (e.g. Opazo, 2005) suggest that it is correctly placed among the caviomorph rodents.

[edit] Gallery

Octodon degus in captivity

Two degus outside

Two Degus snuggling. The one lying down is pregnant.

[edit] External links

[edit] References

  1. ^ Hejna, M. and P. Myers (2006). "Octodon degus". . Animal Diversity Web Retrieved on 2008-04-09.
  2. ^ "What a Rodent Can Do With a Rake in Its Paw", New York Times, 2008-03-26. Retrieved on 2008-04-08. 

[edit] Further Reading

  • Baillie (1996). Octodon degu. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
  • Bacigalupe, L. D., Rezende, E. L., Kenagy, G. J., & Bozinovic, F. (2003). Activity and space use by degu: a trade-off between thermal conditions and food availability? Journal of Mammalogy, 84, 311-318.
  • Bozinovic, E., & Vasquez, R. A. (1999). Patch use in a diurnal rodent: handling and searching under thermoregulatory costs. Functional Ecology, 13, 602-610.
  • Bozinovic, F., & Torres-Contreras, H. (1998). Does digestion rate affect diet selection? A study in Octodon degu, a generalist herbivorous rodent. Acta Theriologica, 43, 205-212.
  • Chavez AE, Bozinovic F, Peichl L, Palacios AG.Retinal spectral sensitivity, fur coloration, and urine reflectance in the genus octodon (rodentia): implications for visual ecology. Invest Ophthalmol Vis Sci. 2003 May;44(5):2290-6.
  • Ebensperger, L. A., & Bozinovic, F. (2000). Communal burrowing in the hystricognath rodent, Octodon degu: a benefit of sociality? Behavioral Ecology and Sociobiology, 47, 365-369.
  • Ebensperger, L. A., & Caiozzi, A. (2002). Male degu, Octodon degu, modify their dustbathing behavior in response to social familiarity of previous dustbathing marks. Revista Chilena De Historia Natural, 75, 157-163.
  • Ebensperger, L. A., Veloso, C., & Wallem, P. K. (2002). Do female degu communally nest and nurse their pups? Journal of Ethology, 20, 143-146.
  • Ebensperger, L. A., & Wallem, P. K. (2002). Grouping increases the ability of the social rodent, Octodon degu, to detect predators when using exposed microhabitats. Oikos, 98, 491-497.
  • Gutierrez, J. R., Meserve, P. L., Herrera, S., Contreras, L. C., & Jaksic, F. M. (1997). Effects of small mammals and vertebrate predators on vegetation in the Chilean semiarid zone. Oecologia, 109, 398-406.
  • Helmeke, C., Poeggel, G., & Braun, K. (2001). Differential emotional experience induces elevated spine densities on basal dendrites of pyramidal neurons in the anterior cingulate cortex of Octodon degu. Neuroscience, 104, 927-931.
  • Jacobs, G. H., Calderone, J. B., Fenwick, J. A., Krogh, K., & Williams, G. A. (2003). Visual adaptations in a diurnal rodent, Octodon degu. Journal of Comparative Physiology A: Neuroethology Sensory Neural and Behavioral Physiology, 189, 347-361.
  • Kenagy, G. J., Veloso, C., & Bozinovic, F. (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, 78-86.
  • Lagos, V. O., Contreras, L. C., Meserve, P. L., Gutierrez, J. R., & Jaksic, F. M (1995). Effects of predation risk on space use by small mammals: a field experiment with a neotropical rodent. Oikos, 74, 259-264.
  • Opazo, J. C. (2005). A molecular timescale for caviomorph rodents (Mammalia, Hystricognathi). Molecular Phylogenetics and Evolution, 37, 932-937.
  • Ovtscharoff, W., & Braun, K. (2001). Maternal separation and social isolation modulate the postnatal development of synaptic composition in the infralimbic cortex of Octodon degu. Neuroscience, 104, 33-40.
  • Vasquez, R. A., Ebensperger, L. A., & Bozinovic, F. (2002). The influence of habitat on travel speed, intermittent locomotion, and vigilance in a diurnal rodent. Behavioral Ecology, 13, 182-187.
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  • Yunger, J. A., Meserve, P. L., & Gutierrez, J. R. (2002). Small-mammal foraging behavior: mechanisms for coexistence and implication for population dynamics. Ecological Monographs, 72, 561-577.
  • Ziabreva, I., Schnabel, R., Poeggel, G., & Braun, K. (2003). Mother's voice "buffers" separation-induced receptor changes in the prefrontal cortex of Octodon degu. Neuroscience, 119, 433-441.