Lutreolina crassicaudata
lutrine opossum

There are two distinct ranges known for thick-tailed opossums, Lutreolina crassicaudata. One range is east of the Andes, between Bolivia and southern Brazil at the northern end, and central Argentina at the southern end. A second range, far to the north and including Guyana, eastern Venezuela, and eastern Columbia, has yielded fewer specimens. ("Genus Lutreolina ", 1989a; Nowak, 1999)

L. crassicaudata occupies grassland, savanna grassland, and gallery woodland, and is often found near areas of permanent water. It is found in areas subject to periodic flooding, and is reportedly the most adapted didelphid to life on the pampas. It has been trapped at elevations up to 1700 m. ("Genus Lutreolina ", 1989b; Marshall, 1978)

The basic body plan of L. crassicaudata is weasel-like. This species has short, rounded ears and a thick tail that is naked at the tip. The tail is prehensile, though not as much as in other didelphid species, and is 210 to 330 mm long. Adults have a head and body length of 200 to 400 mm. As adults, males tend to be larger than females, weighing between 455 and 1100 g, whereas females have been recorded as 176 to 800 g. Though there is no question that females do have a pouch, the amount of development of the pouch is unclear. ("Genus Lutreolina ", 1989a; Lemke, et al., 1982; Nowak, 1999)

Coat color varies within the species. This appears to be a geographic variation, and may be due to differences in diet or climate. The upper part of the coat is generally pale yellow, buff, or dark brown, whereas the under part varies from a reddish-ochraceous to pale or dark brown. (Marshall, 1978)

There is no information on the mating system of L. crassicaudata. However, the sexual dimorphism in size that is found in adults is indicative of intermale competition for mates, and therefore suggests some level of polygyny.

L. crassicaudata is reported to breed twice annually, once in the spring and again after the first litter has become independent. Gestation is short, as is common for marsupials, and is believed to be two weeks. Litter sizes of seven and eleven have been reported, though little other information is available. Although reports indicate that the female has a well developed pouch, the young are reportedly raised in a nest of dry grass. ("Genus Lutreolina ", 1989b; Marshall, 1978; Nowak, 1999)

There is no information available on the parental investment of L. crassicaudata. However, we can assume that like other didelphids, these animals produce altricial young. The mother, as in all mammals, is likely to be the principle care-giver to the offspring, and feeds them with milk. The amount of time the young spend in the pouch has not been documented, and the only information directly available about the juvenile lives of these animals is that they are reared in a nest. There is no information indicating that males play a significant role in parental care. (Nowak, 1999)

There is no information on longetivity in the wild. One captive specimen was reported to have survived for three years. (Nowak, 1999)

L. crassicaudata is an excellent swimmer and climbs well, in addition to being capable of terrestrial living. It is nocturnal. These animals are reported to be more social than other didelphids, and a group containing two females and one male was sucessfully maintained in captivity. It is not known how social these opposums are in natural populations. Little else is known of the behavioral habits of this species. (Marshall, 1978)

The home range, as determined from a limited trapping study, is 800 m^2. ("Genus Lutreolina ", 1989b; Nowak, 1999)

There is no information on the modes of communication in L. crassicaudata. However, it is likely that they are similar to other members of their family, which are known to communicate with a number of vocalizations and visual signals. In addition, opposums generally have tactile communication, between mothers and their young, between mates, and also between rivals. In many species of opposums, physical aggression is common, especially between males. It is likley that L. crassicaudata is similar. (Nowak, 1999)

The species is omnivorous. Individuals are reported to feed on small mammals, birds, reptiles, fish, and insects. In a study of fecal samples to determine diet, crabs, beetles, vertebrates, and fruit were all found. Specimens included animals from the classes Aves and Diplopoda, and the orders Decapoda, Coleoptera, Hymenoptera, Lepidoptera, Orthoptera, and Opiliones. Plants were from the families Arecaceae, Cecropiaceae, Moraceae, Piperaceae, and Solanaceae. One successful captive diet included butterfish, meat, frogs, earthworms, shrimp, and mice. (Caceres, et al., 2002; Marshall, 1978)

Predators and anti-predation behaviors for the species are not reported. However, we may assume that they fall prey to a number of small and large carnivores which inhabit the same habitats.

Though it has not been documented directly, L. crassicaudata exhibits the ecological requirements to be a seed disperser, especially for pioneer or secondary plants. To the extent that any predators rely on this species for food, these animals are likely to have some affect of predator populations. (Caceres, et al., 2002)

At one time in Argentina, the animals were trapped, and their pelts were used for trimming garments. However, this practice has declined, since the color tends to fade from the hairs. (Marshall, 1978)

There are no known adverse affects of L. crassicaudata on humans.

There is no special conservation status for the species at this time.

The species at one time was thought to be composed of many separate subspecies, but Marshall (1978) recognized only two subspecies: L. c. crassicaudata and L. c. turneri. These animals are known as ‘Little Water Opossums', ‘Thick-tailed Opossums', and by humans in their range as ‘Comadreja Colorada'. The latter name comes in part from the common name of the long-tailed weasel (Mustela frenata), comadreja. The chromosome number for the species is 2n=22. ("Genus Lutreolina ", 1989b; Lemke, et al., 1982; Marshall, 1978)