Lutrine opossums are typically found near creeks, streams and other permanent water bodies or flooded areas. In a research study, 93% of lutrine opossums were trapped within 20 meters of a permanent water source. These animals are often found in savannas, wet grasslands and gallery forests. Their specific habitat preferences may be related to their range, including pampas and temperate grasslands in Argentina, Uruguay and Southern Brazil, savanna woodlands in northern Argentina and Paraguay and tropical grasslands and gallery forests in Mato Grosso, Brazil. They are often considered the didelphid species most adapted for life in pampas habitats. Lutrine opossums can be found in the Bolivian Andes at elevations up to 2,000 m. (Caceres, et al., 2002; Lew, et al., 2011; Muschetto, et al., 2011; Nowak, 1999; Regidor, et al., 1999; Santori, et al., 2005; Stein and Patton, 2008)
Lutrine opossums are medium-sized marsupials, similar in size to gray four-eyed opossums. Males of this species are larger than females with a body weight of 737.2 g (+/- 339.7), as opposed to the female’s body weight of 490.4 g (+/- 127.1). Head and body lengths average 316.7 mm (+/- 31.3) in males, with a tail length of 280.5 mm (+/- 19.2), whereas female head and body lengths measured 285.4 mm (+/- 24.9), with a tail length of 259.7 mm (+/- 18.3). Their physical appearance is similar to weasels, with a long, slim body and short legs. Although this species is known to swim, their feet are neither webbed nor enlarged. Lutrine opossums are also known to climb, however, their hallux and pollex are not opposable and their tail is not prehensile. Their soft, thick dorsal pelage is solid reddish, buffy or dark brown and may appear purplish. Their ventral pelage is a lighter, ocher coloration. Their tail is thick and furred at the base; the last 50 mm of their tail is naked on the ventral side, with a dark tip. Lutrine opossums have short rostrums with a reddish muzzle that lacks any distinctive facial markings. Their ears are small and rounded, barely visible above their fur. Their dental formula is similar to all other didelphids: 5/4, 1/1, 3/3, 4/4, with 50 teeth total. In addition, female lutrine opossums have undeveloped pouches containing 9 mammae. (Caceres, et al., 2002; Marshall, 1978; Muschetto, et al., 2011; Nowak, 1999; Regidor, et al., 1999; Santori, et al., 2005; Stein and Patton, 2008)
Many species of didelphids show a polygynous mating system in which males compete for females. Although mating systems have not been studied in lutrine opossums specifically, their sexual dimorphism indicates that polygyny is likely for this species. (Fernandes, et al., 2010; Muschetto, et al., 2011)
Lutrine opossums likely breed twice a year within the span of September to February, during their spring and summer. Their first annual litter is likely born at the end of September and their second litter is likely born in January. After a gestation period of around 2 weeks, they have litters ranging from 7 to 11 young, with a 20:15 male to female ratio. Young likely become sexually mature when they about 6 months old, but probably do not begin breeding until the following season. (Marshall, 1978; Muschetto, et al., 2011; Regidor, et al., 1999; Stein and Patton, 2008)
Very little is known about the parental investment of lutrine opossums. Young are raised in dry grass nests and weaned when they about 3 months old. (Marshall, 1978; Regidor, et al., 1999; Stein and Patton, 2008)
The lifespan of lutrine opossums is not known, however, there is a record of a captive individual surviving 3 years. Their mortality rate is affected by their frequent collisions with cars. (Bager and da Rosa, 2010; Nowak, 1999)
Lutrine opossums are nocturnal and crepuscular. These animals have extremely diverse modes of locomotion; they are agile on the ground, skillful climbers and strong swimmers. Although they are adept swimmers and are almost always found near a permanent water source, lutrine opossums are not truly specialized for semi-aquatic locomotion. Their fur is not water-resistant, they lack large, webbed feet and they use a primitive paddling method. Likewise, although lutrine opossums are good climbers, they lack a prehensile tail and an opposable hallux and pollex. Lutrine opossums construct nests in tree holes and in grasses; they also use the abandoned burrows of armadillos and viscachas. In laboratory tests, lutrine opossums showed a startled, frozen response when presented with aversive stimuli. Interestingly, this species shows a remarkably high rate of REM sleep. A captively housed male has been successfully held with 2 females, which has led some to believe that this species may be more social than other didelphids. (Caceres, et al., 2002; Gravett, et al., 2012; Marshall, 1978; Muschetto, et al., 2011; Nowak, 1999; Papini, 1988; Regidor, et al., 1999; Santori, et al., 2005; Stein and Patton, 2008)
The home range size of lutrine opossums has not been fully studied; however, in Argentina, their home range has been estimated at 3,800 square meters. (Nowak, 1999)
Lutrine opossums produce high-pitched whistle sounds when they perceive danger, but may also produce similar sounds as a form of social contact. These animals likely produce a variety of olfactory signals as well. Olfaction is important for most marsupials as it facilitates their trip to their mother’s pouch directly after birth. Generally, didelphids also have good eyesight and hearing, although the specific sensory functions of lutrine opossums are not known. (O'Connell, 2006; Smith, 2009)
Lutrine opossums may have slightly different feeding preferences depending on their range, although in general, these animals are often considered the most carnivorous didelphid species. Within their Brazilian range, their diet is primarily composed of crabs and beetles, although they are also known to eat a variety of other invertebrate and vertebrate animals as well as fruits and seeds, specifically from Ceropia glaziovii and piper plants (Piperaceae). In central Argentina, these animals consumed amphibians, birds, arthropods, snails, seeds and vegetation. In other ranges, these animals are also known to feed on fish and small mammals. During their warm season, March through May, lutrine opossums consume a significantly larger quantity of plant material. (Caceres, et al., 2002; Lew, et al., 2011; Muschetto, et al., 2011; Regidor, et al., 1999; Santori, et al., 2005)
Lutrine opossums are likely prey for manned wolves and are known prey for outdoor domestic cats and dogs. Likewise, although lutrine opossums are immune to the venom of several snakes, including Bothrops jararaca, the remains of juvenile lutrine opossums have been found in the scat of rattlesnakes. Young lutrine opossums may also fall victim to a variety of predatory birds including roadside hawks, great horned owls and barn owls. (Campos, et al., 2007; Perales, et al., 1994; Sant'anna and Abe, 2007; Smith, 2009; da Silva Belentani, et al., 2005)
Lutrine opossums are believed to be seed dispersers. They drop an average of 765 seeds in their scat per night. Specifically, the Cecropia seeds in their diet remain viable for germination after passing through their digestive tract. Likewise, lutrine opossums are known to carry a variety of parasites including nematodes, ticks and protozoan. (Barros and Baggio, 1992; Caceres, et al., 2002; Navone, et al., 1991; Tasca, et al., 2001)
Currently there are no known positive economic impacts from lutrine opossums on human populations; however, in the past, their fur had been used in clothing. (Smith, 2009)
Lutrine opossums may cause negative economic effects due to their tendency to raid chicken coups and pigeon lofts. (Nowak, 1999)
Currently, lutrine opossums are listed as a species of least concern according to the IUCN Red List of Threatened Species. These animals are believed to have a relatively large population size and can be found in a variety of protected areas. (Lew, et al., 2011)
Lutrine opossums are known by a variety of names, including ‘thick-tailed opossums’, ‘red opossums’ and ‘little water opossums’. In addition, their physical similarity to mustelids has also given them the names ‘mink-opossum’ and ‘comadreja’, the Spanish word for weasel. (Lew, et al., 2011; Muschetto, et al., 2011; Smith, 2009)
Leila Siciliano Martina (author), Animal Diversity Web Staff.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
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.
uses smells or other chemicals to communicate
active at dawn and dusk
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.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
breeding is confined to a particular season
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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