Notes on the Activity, Reproduction, and Social Behavior of Octodon degus

Abstract

Data on activity and social behavior of the Chilean degu, Octodon degus, were gathered by direct observation of animals, some of which had been marked for individual recognition. Data from autopsies and external inspection of trapped animals suggested that most reproduction occurs in September at the latitude of Santiago. Degus are diurnal and show morning and evening activity peaks. Social organization is based on group territories, at least during the period after emergence of the young. Mound building (collecting a pile of sticks, stones, and cow dung) was associated with territorial marking. Females of the same social group may rear their young in a common nest burrow. Octodon degus burrows are sometimes used by Abrocoma bennetti, a similar sized rodent, and on two occasions nest burrows were found to be shared by young and mothers of both species.Octodon degus is a common rodent in central Chile and one of the most economically important. In some areas it is an agricultural pest. Degus do considerable damage to cultivated tuna, the edible fruit of the prickly pear cactus; Ipinza et aZ. (1971) reported that degus are known to damage wheat fields, vineyards, and orchards. Pefaur et aZ. (1968) reviewed the parasitological literature and reported that O. degus can host three species of parasites known to infect man. In the United States, this hystricomorph is becoming widely used in medical laboratories (Woods and Boraker, 1975).Despite the importance and abundance of O. degus, information on its natural history is almost completely lacking. Woods and Boraker ( 1975) provided a complete review of the literature on the species. In this paper I report observations made on a natural population of O. degus. METHODSThis study was carried out at the experiment station of the School of Agronomy of the University of Chile at Rinconada de Maipu (70 0 50'W, 33°31'S) near Santiago. The vegetation was a mixture of grasses and shrubs and was greatly influenced by cattle grazing. The dominant woody plants were Acacia caven and Proustia cuneifolia. Olivares and Casto (1971) described secondary plant succession at this site and the influence of Octodon degus on the herbaceous strata. Climatic data were given in Fulk (1975).Reproductive data were gathered by autopsy of kill-trapped animals and by inspection of live-trapped animals.Activity was monitored by making frequent 15-minute observations during the daylight hours for one day each month for six consecutive months beginning in May 1973. The number of animals seen in a delineated area around an elevated observation blind was considered a measure of activity. Between observations, air temperature in the shade 5 centimeters above the ground, sunlight intensity, and relative humidity were recorded.Information on social behavior was gathered by observing a nearby colony of degus from a similar blind. Before the start of observations, animals were live trapped, examined for reproductive condition, weighed, marked for individual recognition by hair clipping, 495

Daily and seasonal limits of time and temperature to activity of degus

“…Two other species of Octodon and the rest of the South American endemic family Octodontidae are all considered nocturnal (Contreras et al 1987). Although most reports indicate O. degus is diurnal (Fulk 1976, Yáñez & Jaksic 1978, Iriarte et al 1989, possible contradiction was raised (Iriarte et al 1989). Our explicit trapping design revealed a lack of nocturnal activity any time of year.…”

“…As the only endemic small mammals of central Chile that are routinely active in the daytime, their conspicuous diurnal activity attracted the attention of the Italian naturalist Molina (1782), who mistakenly identified them as squirrels. Their general activity, reliance on shrub cover as a refuge from heat and predators, and thermal response to heat loads have been described by Fulk (1976), Yáñez & Jaksic (1978), Iriarte et al (1989), andLagos et al (1995), though these previous studies did not assess seasonality. Degus are generally associated with shrub cover and variable amounts of open space in which they forage (Le Boulengé & Fuentes 1978, Jaksic et al 1981a, Meserve et al 1984, Iriarte et al 1989.…”

Parental Deprivation Induces N‐Methyl‐D‐Aspartate‐Receptor Upregulation in Limbic Brain Areas of Octodon degus: Protective Role of the Maternal Call

“…Unlike rats and mice, degu pups are born with functional sensory systems, and this relative maturity of the sensory systems allows the newborn pups, like human newborns, to perceive and to respond to familiar and novel stimuli, including con-specific vocalizations, immediately after birth. The species is characterized by a highly elaborated vocal repertoire, which is used for communication among parents, offspring, and other group members (Fulk, 1976). The newborn pups must learn to recognize and to respond to the mother's vocalizations within the first days of life (Poeggel & Braun, 1996;Braun & Scheich, 1997), which is analogous to behavior observed in human babies (De Casper & Fifer, 1980 (Poeggel & Braun, 1996;Braun & Scheich, 1997 For the autoradiographic analysis, 14-day-old animals from the SPS (5 males, 6 females) and SPS+T (6 males, 6 females) groups were used.…”

Vaginal leiomyosarcoma in a degu (Octodon degus): a case report

“…Degus typically live in small groups and are very social animals. They are used in research studies investigating circadian rhythms, diurnal behaviour and physiology (Fulk, 1976;Nowak, 1999;Lee, 2004). There are only a limited number of reports in the literature regarding tumours in degus (Murphy et al, 1980;Anderson et al, 1990;Lester et al, 2005;Jekl et al, 2008) and, there is no publication documenting a genital tumour in the ovary, uterus or vagina of a degu.…”