Galictis vittata

Geographic Range

Greater grisons are native to Neotropical regions including Central and South America. They have been documented as far north as Mexico and as far south as Argentina. The total geographic range for this species is estimated at 13,083,600 km2, although their population density is low within that range. Their range may overlap with their smaller relative, lesser grisons ( Galictis cuja ).

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Greater grisons occupy a wide variety of terrestrial habitats, though they are generally found near streams, rivers or wetlands. Much of their time is spent in closed habitats including deciduous, rain, tropical or dry forest and shrub woodland. They have also been observed in open savanna, as well as cultivated areas such as plantations, cane fields or partially flooded rice fields. Galictis vittata occurs at elevations as high as 1,500 m above sea level, though it is usually found at lower elevations, most often below 500 m.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest

• Other Habitat Features
• agricultural agricultural

Physical Description

Greater grisons are often described as large weasels . They have long, slim bodies, with short legs and a short, long-haired tail. Their toes have pearlescent blue claws and are padded and partially webbed along approximately three quarters of their length. Galictis vittata has a small, flat head with small, whitish, relatively broad, rounded ears and brown or black eyes that reflect blue light in the dark. Most striking of all is the coloration of their fur, which itself is fairly coarse, with a softer undercoat. Their dorsum is grey and separated from their black or grizzled under-parts by a light-colored, half-inch wide stripe running across their forehead and down the sides of either shoulder. Greater grisons are similar in appearance to their close relative, lesser grisons , but can be distinguished from the latter based on their larger size and their white or grey-tipped dorsal guard hairs, compared to the buff yellow-tipped dorsal guard hairs of lesser grisons . Their body length, including their tail, ranges from 60 to 76 cm, with weight records ranging from 1.4 to 3.8 kg. Female greater grisons tend to be slightly smaller and more slender than males. One team of researchers recorded a length of 68.58 cm for their captive male grison, compared to 60.96 cm for their captive female. Similarly, the captive male had an average mass of 3.3 kg compared to 1.8 kg for the female, a difference of 1.5 kg. As is typical of most mustelid species, males have a baculum. Both males and females have anal glands on either side of their anus. The dental formula for this species is I3/3 + C1/1 + P3/3 + M1/2, giving Galictis vittata a total of 34 teeth.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Information on the mating system of greater grisons is lacking; however, their close relative, Galictis cuja , may potentially be monogamous.

• Mating System
• monogamous monogamous

The birth of their offspring has been recorded in every month between March and October, excluding April and July. Gestation is about 39 days, with an average of one offspring per litter and a maximum of four. Young are born quite helpless, with closed eyes and weigh less than 50 g, although their hair is short, the characteristic coat pattern is already evident. Around one week of age, offspring open their eyes and by two weeks, they are able to eat meat successfully, although offspring are not completely weaned until about three and a half weeks of age. Greater grisons are fully grown at four months of age, around the same time that the testes descend in males.

• Key Reproductive Features
• iteroparous iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Female greater grisons nurse their offspring until they are weaned at approximately 3.5 weeks of age. Small groups of grisons observed hunting and exploring together are usually assumed to be mothers with older offspring, indicating that offspring likely associate with their mothers for a certain amount of time post-weaning.

• Parental Investment
• altricial altricial
• female parental care female parental care
• post-independence association with parents

Lifespan/Longevity

The lifespan of Galictis vittata has not been recorded for wild populations; although, there has been a published description of a captive grison still living at ten years and six months of age.

Behavior

Greater grisons are primarily terrestrial and move quickly in a zig-zag pattern to various locations. While on the move through tall grass, they often pause and extend their neck and head above the grass to sniff and observe their surroundings. They have been observed burrowing and are adept swimmers; they have also been observed climbing partway up trees, apparently for exploratory purposes. Both wild and captive grisons have been described as being both playful and very inquisitive. Play often takes the form of wrestling and gentle biting. No social grooming has been observed. When faced with an unfamiliar object, grisons will slink toward the object; body outstretched, low to the ground and retract swiftly if disturbed. When alarmed, greater grisons jump backwards, snort and emit a foul-smelling musk from their anal glands, the trajectory of which, they are able to aim and use against specific targets, similar to skunks . Greater grisons tend to urinate and defecate in dark corners or nooks, generally using the same location each time. They squat and raise their tails during the act of elimination. Whether greater grisons are nocturnal or diurnal is an issue of contention among researchers. Many report that the animals are entirely diurnal, while others report that they are active throughout the night. Most, if not all, researchers appear to be in agreement that grisons are crepuscular, with periods of rest four or five hours long during the middle of the day and bouts of activity in the early morning and late afternoon. Grisons tend to sleep in burrows, such as those made by agoutis or armadillos .

• Key Behaviors
• crepuscular crepuscular
• motile motile

Home Range

Wild grisons that are active during the night have been recorded traveling distances of 1.3 to 2.7 km; their individual home range has been estimated at upwards of 415 hectares, though there is a low population density within that range.

Communication and Perception

Greater grisons communicate a number of ways, though based on observations in the field; it would seem that they have a greater reliance on olfaction than on vision. They engage in scent marking, by brushing their musk-coated tails over surfaces. Grisons also have a wide variety of vocalizations, including: snorting when alarmed or upset, purring when stroked, panting when moving from place to place, squealing during play and barking during aggressive displays.

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Greater grisons are carnivores, though they are also quite opportunistic and will eat some plant matter, such as bananas , if offered. In the wild, their prey of choice depends on their specific locale, but in general, they hunt primarily mammals , such as agoutis and opossums . The stomachs contents of wild grisons have also been found to contain amphibians , invertebrates , reptiles , and birds . Grisons have been observed hunting in pairs as well as alone. When attacking prey, greater grisons aim for the back of the head or neck of their prey and bite down hard to kill. In captivity, grisons have been observed holding food items with their forepaws, although they do not appear to use their feet to actually manipulate food items.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates

• Animal Foods
• birds
• mammals
• amphibians
• reptiles

• Plant Foods
• fruit

Predation

Information regarding predators of this species is not available.

Ecosystem Roles

The primary role that greater grisons fill in their ecosystem is that of a predator, namely, preying on small terrestrial vertebrates. In addition, greater grisons may act as vectors for various diseases. Like many carnivores, they are susceptible to canine distemper . Grisons may also contract a fungus, Paracoccidioides brasiliensis , in their lungs. They are hosts to ticks, such as Amblyomma ovale and Amblyomma aureolatum and are susceptible to Trypanosoma cruzi .

Economic Importance for Humans: Positive

If raised in captivity from a young age, greater grisons reportedly make affectionate pets. In some instances, they are also kept in captivity for the purpose of controlling rodent populations.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

Greater grisons are not valuable as game, but they may become an agricultural nuisance. In some instances they may prey on domestic chickens .

Conservation Status

The International Union for Conservation of Nature and Natural Resources lists Galictis vittata as a species of least concern for conservation, due to the absence of major threats and its wide area of distribution. Population trends are listed as stable.

Additional Links

Encyclopedia of Life

Contributors

Mackenzie Gregg (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Leila Siciliano Martina (editor), Texas State University.

References

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