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Brief Summary

    Greater grison (Galictis vittata)
    provided by EOL authors
    The greater grison is a species of mustelid native to South and Central America, ranging from eastern and southern Mexico south to central Brazil, Peru, Bolivia and northern Argentina. It inhabits various habitats from tropical evergreen, scrub and rain forests to grasslands, savannas, cerrado and cultivated areas, such as plantations and rice paddies, usually near rivers and streams, but not in great numbers (7). It usually lives at elevations below 500 m, but may occur as high as 2,000 m in some parts of the Bolivian Andes [2,6]. In some regions, it may occur found in cultivated areas, .

    The grison is a slender animal with a long, muscular body, short legs, a long neck, and a short, bushy tail. The fur is long and soft. The ears are very small and the small, black eyes are small and blackThe grison's eyeshine is a bright blue-green color. The broad feet have very long claws. It resembles the closely related lesser grison, but is larger, with a head-body length of 45-60 cm, a tail length of 14-20 cm and a weight of 1-3.8 kg in the wld, although captives may be larger (2). The upper part of the body is grizzled grey. The underbody, including the legs and feet, are black. The head has a grizzled grey forehead and a black face and neck. A white stripe runs from the forehead over the ears and to the shoulders. The back, flanks, top of the head and the tail are grizzled grey; the rest of the body is much darker, usually solid black. A narrow whitish stripe separates the darker and lighter fur on the head and shoulder, but not further back, where the two colours may, in some individuals, blur into one another. The tail is covered with bushy hair similar in colour to that on the back. The flattened, broad head has short, rounded ears and dark brown to black eyes. The muscular legs have 5 webbed toes, each ending in a sharp, curved claw [2].

    The grison is primarily terrestrial, but can climb trees and swim well. It is mostly diurnal and only occasionally active at night [4]. It lives live alone or in pairs, with home ranges of at least 4.2 sq km (1.6 sq mi), and a very low population density, so it is rarely encountered in the wild. It spends the night sleeping in crevices in rocks, cavities in hollow logs or beneath tree roots or in abandoned burrows dug by armadillos and other animals [4]. The anal scent glands secrete a yellowish or greenish musk. It is not especially noxious compared with that of other species, but can be sprayed at attackers and is used to mark the grison's territory [2]. The grison unistic specieshas been said to respond to threats with a series of grunts, rising in intensity and frequency to until they become rapid barks, and finally a single loud scream with their teeth bared.[2]<

    The grison is a very opportunistic species, eating whatever is available. The diet includes chinchillas, viscachas, agoutis, mice and other small mammals, birds and their eggs, lizards, amphibians and fruits (5,6). While hunting, it moves in a zigzag pattern, making short bounds and occasionally stopping to look around with its head raised while it sniffs the air. When moving more cautiously, it presses its body close to the ground in a snake-like movement. The grison is polygynous. Litters of two (up to four) young are born from March-October, after a gestation period of 39-40 days. Newborn young weigh under 50 g (1.8 oz), are initially blind, but have a short coat of hair bearing the adult pattern. The eyes open after 2 weeks, and the young begin eating solid food at 3 weeks, reaching adult size in 4 months [4]. Grisons may live 10.5-13 years in captivity [2,8].


    The IUCN Red List Assessment for the greater grison is 'Least Concern', due to its large range. The grison is rare with a low density throughout its range (9,11). It is considered endangered in Costa Rica(10) and is listed on CITES Appendix III (In Costa Rica, it is considered endangered (Timm et al. 1989) and is listed on CITES Appendix III (Fuller et al. 1987). In Belize it is protected by the Wildlife Protection Act, and in Nicaragua it is protected from hunting (13). In Belize it is protected by the Wildlife Protection Ac, and in Nicaragua it is protected from hunting (13). Some subspecies are considered uncommon or rare (10). The Population Trend is Stable. The species tolerates some disturbance, but hunting shows negative effects (12). In some parts of their range, males are trapped for their body parts and they are also sold as pets (7). Learn more about this article

    The grison has been known to cause damage to domestic animals.



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    Economic Importance for Humans: Positive

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    The grison is tamed easily. The grison is helpful in controlling rodent infestations. They are also used by man to hunt chinchillas.



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    There are four living and one fossil subspecies [3]:

    •Galictis vittata vittata - northern South America

    •Galictis vittata andina - Peru and Bolivia

    •Galictis vittata brasiliensis - Brazil

    •Galictis vittata canaster - Central America and southern Mexico

    •† Galictis vittata fossilis - Pleistocene Brazil[2]. xx
    Greater grison: Brief Summary
    provided by wikipedia

    The greater grison (Galictis vittata), is a species of mustelid native to Southern Mexico, Central America, and South America.

Comprehensive Description

Distribution

    Distribution
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    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 (Native )

Morphology

    Morphology
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    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.

    Range mass: 1.4 to 3.8 kg.

    Range length: 600 to 760 mm.

    Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

    Sexual Dimorphism: male larger

Habitat

    Habitat
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    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.

    Range elevation: 500 - 1500 (high) m.

    Habitat Regions: tropical ; terrestrial

    Terrestrial Biomes: savanna or grassland ; forest ; rainforest

    Other Habitat Features: agricultural

Trophic Strategy

    Trophic Strategy
    provided by Animal Diversity Web

    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.

    Animal Foods: birds; mammals; amphibians; reptiles

    Plant Foods: fruit

    Primary Diet: carnivore (Eats terrestrial vertebrates)

Associations

    Associations
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    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.

    Commensal/Parasitic Species:

    • Paracoccidioides brasiliensis
    • Amblyomma ovale
    • Amblyomma aureolatum
    • Trypanosoma cruzi
    Associations
    provided by Animal Diversity Web

    Information regarding predators of this species is not available.

Behavior

    Behavior
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    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 ; chemical

    Other Communication Modes: scent marks

    Perception Channels: visual ; tactile ; chemical

Life Expectancy

    Lifespan, longevity, and ageing
    provided by AnAge articles
    Maximum longevity: 12.5 years (captivity) Observations: One wild born specimen was 12-13 years old when it died in captivity (Richard Weigl 2005).
    Life Expectancy
    provided by Animal Diversity Web

    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.

    Range lifespan
    Status: captivity:
    10.5 (high) years.

    Average lifespan
    Status: captivity:
    10.5 years.

Reproduction

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

    Mating System: 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.

    Range number of offspring: 2 to 4.

    Average number of offspring: 2.

    Average gestation period: 39 days.

    Average weaning age: 3.5 weeks.

    Average age at sexual or reproductive maturity (male): 4 months.

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

    Average gestation period: 40 days.

    Average number of offspring: 2.

    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 ; female parental care ; post-independence association with parents

Conservation Status

    Conservation Status
    provided by Animal Diversity Web

    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.

    US Federal List: no special status

    CITES: appendix iii

    State of Michigan List: no special status

    IUCN Red List of Threatened Species: least concern

Benefits

    Benefits
    provided by Animal Diversity Web

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

    Benefits
    provided by Animal Diversity Web

    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