Genus Cricetomys AFRICAN GIANT POUCHED RATS
G. gambianus, Senegal to central Sudan, and south to South Africa
G. emini, Sierra Leone to Lake Tanganyika, island of Bioko (Fernando Poo)

(note: The majority of these rats found in captivity as pets are G. gambianus. There are only a few G. emini found in zoos.)

Head and body length is 240-450 mm and tail length is 365-460 mm. Weights of 1.0-2.8 kg for males and 0.96-1.39 kg for females....
... These rats dwell in forests and thickets. They are nocturnal but have been seen foraging during the day, at which time they behave as if they were almost blind, sitting on their haunches and sniffing in all directions. They can climb well, using the long tail for balancing, and can swim. For shelter they often use natural crevices and holes, termite mounds, or hollow trees, but they can dig their own burrows, which consist of a long passage with side alleys and several chambers, one for sleeping and the others for storage. The burrows have two to six openings and are frequently located at the base of a tree or among dense vegetation; the entrances are often closed that in Zimbabwe many less complex burrows have been found, consisting of a straight tunnel, some not more than 1.5 meters long, with a single nesting chamber at the end.
Ajayi stated that these rats are completely omnivorous, feeding on vegetables, insects, crabs, snails, and other items but apparently preferring palm fruits and palm kernels. Ewer stated that the cheek pouches are used to carry food and bedding material and that there is regular coprophagy. According to Kingdon, these rats store a considerable amount of food, as well as many non edible items, such as coins, metal, and bits of cloth.
Cricetomys is generally solitary; a captive male and female may be kept together, but two mature males may fight to the death. Reproduction takes place at various times of the year. In a study of captives, Ajayi observed one female to give birth 5 times in 9 months, and he thought that probably females could produce 10 litters annually. The gestation period was 27-36, usually 30-32, days. Litters numbered 1-5, most commonly 4, young. Sexual maturity was attained at about 20 weeks. According to Jones, a captive specimen lived for 7 years and 10 months.
These animals are timid but soon become tame in captivity and make delightful pets. They are in great demand as food by the native tribes. Studies have been made of their potential for domestic production of food. In some West African towns, Cricetomys has become a sewer rat and is killed along with Rattus by the rat catchers. In contrast, C. gambianus is classified as rare in South Africa.


Reference:
Novak, R.M. and Paradiso, J.L. 1991. Walkers Mammals of the World, Vol II. The Johns Hopkins University Press, Baltimore.


Giant Rat Cricetomys gambianus
...... Habitat: forest and woodland but occasionally urban areas.
Behavioral: Mainly nocturnal but if undisturbed can be diurnal. Digs own burrow but also makes use holes, hollow trees and piles of plant debris. Surplus food is carried in cheek-pouches to store. When a burrow is occupied it is usually closed from the inside. Placid and generally harmless. Food: Fruits, roots and seeds (including cultivated crops); occasionally insectivorous.
Reproduction: 2-4 young, each weighing about 20 g. are born in summer.
Reference:
Stuarts, Chris and Tilde. 1988. Field guide to the mammals of southern Africa. New Holland.


AFRICAN GIANT POUCHED RAT IN CAPTIVITY

Scientific name: two species of genus Crietomys.
Origin: C. gambianus is found from Senegal to central Sudan and south Africa, and C. emini from Sierra Leone to Lake Tanganyika and Fernando Po.
General characteristics: The African Giant Pouched Rat has rather a long narrow head, cheek pouches and a scaly tail. The animals are timid, but soon become tame when used to their surroundings and make delightful pets.
The head and body length is 240-250 mm, with a tail length of 365-460 mm.
Males weigh about 1.5 kg and females up to 1 kg.


The fur is short and thin. The coloration of the mid dorsal regions range from dark grayish brown to medium grayish, with a tinge of brown or clear reddish brown. The general coloration becomes paler on the sides, sides of the face and flanks, ranging from gray with a brownish tinge to reddish brown or buff. The conspicuous ears are practically naked, the dorsal two thirds are dark grayish and the remainder soiled white or cream. Many individuals are mottled gray or almost spotted, mainly on the anterior half of the upper parts. This mottling may be inconspicuous, many from irregular small spots or blotches or may cover almost all of the upper parts.
In some areas there is a fairly definite, almost white, stripe across the back just behind the shoulders.
Housing: Naturally with such a large rodent, an equally large cage is required. I would advise that you attempt to build your own, rather than try to buy one, as you will then be able to construct a more suitable cage in size and to your own personal needs. It should, ideally, be made of either metal or lined with metal, as this rodents is extremely good at gnawing through wood.
Grouping: Generally solitary, a captive male and female may be kept together, but two mature males may fight to death.
Breeding: Gestation period is 27-36 days, each litter numbering 1-5, most commonly 4. They are sexually mature at about 20 weeks. Captive life span is about 6 years.
Diet: In the wild the African Giant Pouched Rat is completely omnivorous and thus they are extremely easy to feed in captivity.


Reference:
Henwood, C. 1985. Rodents in Captivity. Ian Henry Publications, Hornchurch

GAMBIAN GIANT POUCHED RATS (Cricetomys gambianus Waterhouse 1840) IN SOUTHERN AFRICA

REFERENCES: Skinner, J.D. and Smithers, R.H.N. 1990. The Mammals of the Southern African Sub region. University of Pretoria.

AFRIKAANS NAME: Reuse rot

COLLOQUIAL NAME

The giant rat is so called as it is the largest murid species occurring in Africa. In the northern parts of its range it is known as the pouched rat.

DISTRIBUTION

The giant rat, C. gambianus, has a wide distribution south of the Sahara. Within the limits of the Sub region they are confined to the eastern parts of the continent in areas with a mean annual rainfall in excess of about 800 mm.

SOUTH OF THE SAHARA, EXCLUDING THE SOUTHERN AFRICAN SUB REGION

They occur from Senegal eastwards to the southern Sudan; in Uganda; southwestern Kenya; northern and central Tanzania; Zaire; Angola and northwards coastally to Gabon. They are recorded widely in Zambia, excluding the southwest; in Malawi and in Mozambique, north of Zambezi River, except in the northeast.

SOUTHERN AFRICAN SUB REGION

They are recorded widely in Mozambique, south of the Zambezi River, excluding the more arid southwestern parts of the country; in northeastern and eastern Zimbabwe, with records from the Matopo Hills, an island of slightly higher rainfall in the west of the country; from the Soutpansberg in the northern Transvaal and Natal, which marks their most southerly limits on the continent.

HABITAT

In the Sub region they occur in evergreen forest and in woodland in the higher rainfall areas (over 800 mm of mean annual rainfall), where there is adequate undercover. They are very common in the urban and periurban areas of towns in the northeastern and eastern parts of Zimbabwe, using the cover of hedges and shrubbery's. Urban development appears to have created particularly suitable habitat for the species, especially in its provision of a plentiful food supply.

HABITS

Predominantly nocturnal, giant rats occasionally may be active in late afternoon or early morning. They restrict their activity to short periods in areas with adequate vegetational cover, and this is permitted by consuming hoarded food within the burrow. They are terrestial and, although they will climb trees in search of fruit if there is none available on the ground, climbing is unusual. Their burrows are sometimes constructed in old termite mounds but are generally located in moist, shaded areas under boulders or at the bases of large trees. It has been suggested that their location is dependent upon soil texture, but more probably these protect them from high ambient temperatures as under experimental conditions found they are unable to cope with temperatures above 34C. At the entrances to the burrows are piles of recently excavated soil which, characteristically, are in the form of small consolidated pellets, perhaps so shaped because the giant rats use their incisor teeth in burrowing, as their front claws are not well adapted to this purpose. Knight reported that the number of entrances vary from one to three, with a mean diameter of 196 ± 85,5 mm, and the main entrances are never sealed as found by morris. Their burrows invariably have a vertical shaft leading from the entrance, several chambers, one of which is a latrine and another, the nesting chamber, lined with sticks and leaves, amongst which is a store of food. Burrow tunnels average 136,7 ± 38,3 mm in diameter and the number of chambers vary from one to five, with only one of these used for nesting. The chambers have an average diameter and height of 454,6 ± 187,7 mm and 256,4 ± 98,2 mm respectively and are 727,1 ± 90,1 mm below the surface. Entrances to the nesting chamber are often sealed with rocks and sand, while a number of escape tunnels also exist in most burrows are used for defecating and feeding, both types being protected on three sides and from above. Knight found that burrow temperatures vary seasonally in forests in the Soutpansberg, northern Transvaal from 9,6 ± 2,1 C at a depth of 700 mm in winter to 20,5 ± 2,6 C in summer when respective forest temperatures (50 mm above ground) are 12,7 ± 1,9 C and 18,6 ± 0,2 C respectively. In Zimbabwe many less complicated burrow systems are found which are used an a less permanent basis. These consist of a straight burrow, oval in section, about 100 mm to 140 mm in diameter, which leads under rocks, the roots of trees, or the floors of outhouses. some penetrate not more than 1,5 m from the entrance, with a single chamber at the end and, in some cases, an additional latrine chamber. Nesting chambers are floored with the inedible parts of fruits and bulbs and a miscellaneous collection of all sorts of nonfood items such as small stones, bones, nails, string, wire, and press caps off mineral water bottles. Indeed, giant rats seem to be prone to collecting any small, brightly colored objects and carrying them back to the nest. Many of these burrow systems are occupied by a solitary individual. In Zimbabwe a gravid female accompanied by a male was dug out of one burrow, suggesting that the pair remain together when breeding. Ewer found no difficulty in keeping males and females together in captivity, even after the female had produced her litter and the female showed no signs of attempting to exclude the male from the nest. Giant rats are slow moving and docile when not alerted. Often, if caught in live traps, they will feed out of the hand immediately after being caught, but the females can be aggressive when they have a litter and will bite fiercely. They will turn on an aggressor if provoked, sit up on their haunches, blow up their cheek pouches and let out a noisy blast of air as a defense mechanism. Of each nocturnal period, 67% is spent sedentary within the burrow, 9,5% active within the burrow and 23,4% active outside the burrow, the first and most active period lasting from 19h00 and then later from 10h00 to 05h00. Home range size averages 4,95 ± 4,18 ha (range 2,23-11,10 ha), with males having larger home ranges than females, while females concentrate their activity closer to the burrow than males. Avoidance of preditation is very important, and giant rats achieve this first by spending a limited time predominantly within the forest scrub.

FOOD

Giant rats have complex gut structures and slow passage rates, enabling them to utilize poor quality food. They are omnivorous, their principal food being vegetable matter, together with a smaller amount of insects, such as termites. Coprophagy was noted by Ewer at 20 days of age, when the young eat the female's feces, which suggests that giant rats also employ gut microbes to assist digestion. In the Transvaal, Knight recorded their preference for soft fleshy fruits. They are larder hoarders and carry back smaller food items in their cheek pouches and larger pieces in their teeth to be consumed or temporarily stored in the nesting chambers or outside feeding shelters. Knight recorded the recovery of 8,7 kg of pericarps of macadamia nuts from a single nesting chamber in the Transvaal. The inedible portions are amalgamated into the lining of the nesting chamber and these, together with stored food, indicate that a very wide variety of fruits, both wild and cultivated, grains, bulbs and tubers are eaten. In Zimbabwe, these include the fruits of mahobohobo, Uapaca kirkiana; marula, Sclerocarya birrea; mobola plum, Parinari curatellifolia; buffalo thorn, Ziziphus mucronata; large sourplum, Ximenia caffra; monkey orange, Strychnos spp, and bauhinia, Bauhinia spp when available. Cultivated fruits such as avocado pears, mangoes, pecan and macadamia nuts are much sought after and they will climb the trees to get at a the fruits if these are not available on the ground. Many types of bulbs and tubers are taken, both wild and cultivated , as well as maize cobs, sorghums, wild and cultivated peas and beans, pumpkin and peanuts. Stomach contents show the remains of termites and other small but unidentifiable insects. They will drink water and appear to be dependent on its availability through direct use or from fleshy fruits. Giant rats can become problem animals where vegetables are grown. Forty-two were taken off a 0,5 garden in Harare, Zimbabwe, where they were eating young plants of peas, lettuces and cabbages.

REPRODUCTION

Information on the times at which the young are born in the wild is lacking and no gravid females were found in a sample of 100 taken in all months of the year, in Harare. One female taken in the Eastern Districts in August carried two fetuses, whilst in Malawi, Morris recorded young in September, January, March and May. During courtship in captivity Ewer reported that the male approaches a female and attempts to copulate, but the female at first responds defensively, rearing up on her hind legs and pushing the male off with her paws. The two then both rise up on their hind legs and male attempts to push the female backward, this process continuing over a distance of several meters. Neither make any attempt to bite, but if the female shows signs of moving away, the male catches her in his teeth pulls her back. The male then grooms the female around the face, ears and nape of the neck, which has a calming effect on her. He then places his forelegs around the middle of her body, with the palms of his hands directed backwards so that the wrists are in contact with her sides, vibrating the forelegs backwards and forwards, in what Ewer interpreted as an assurance behavior. Ewer found that three pairs of female gave birth after cohabiting with males for 32. 32 and 31 days and because sexual behavior was observes in these three pairs after five, four and three days, the gestation period appears to be between 27 ja 28 days. In the wild the young are born in the nests and after cleaning the young, the female eats the afterbirth. Birth masses range from 19,0 g to 33,4 g. Litter size in captivity and in the wild varies from two to four. Ewer found that the altricial young are born naked, except for whiskers, the body unpigmented and the eyes closed. At two days of age mass of two pups averaged 27,43 g, increasing to 461,70 g by day 52, with average growth rates of 3,8 g/day. at birth the tail is only 30% to 40% of the length of the body, but at 80 days it reaches the same length. Skin pigmentation starts to develop on the young at about four days after birth an by the fifth day the line demarcating the white tail tip develops. Fine hair develops on their bodies by the fifth day and after 10 days forms a silky covering. Pinnae only become free after seven days, and the eyes open at 28 days. * At the 11th or 12th day a behavior patter occurs in a number of litters in which the young engage in what Ewer described as ”outbursts of insensate rage”, fighting and biting each other. Peace is not restored until the mother returns to suckle them. The female remains with the young until they are about a week old and only then is prepared to leave them to forage. She suckles them by crouching over them and in captivity the pups first attempt to eat solid food at the age of 17 days, taking it a day later. The eyes open at an age 20 to 24 days when they first leave the nest to urinate, using the common latrine. In the wild, Knight only managed to catch two young during 411 trap nights over two years and he estimated these animals to be between 60 and 98 days old. He suggested they do not leave the burrow until a late stage of development. In captivity their first foraging journeys were undertaken between 43-52 days and they finally deserted the nest at 86 days when they were able to thermoregulate. As giant rats tame easily, are cheap to feed, and reproduce well in captivity, schemes to introduce farming enterprises have been studied in West Africa where giant rat meat is considered a marketable proposition.

REFERENCES: Skinner, J.D. and Smithers, R.H.N. 1990. The Mammals of the Southern African Subregion. University of Pretoria.
Petri Airasvirta
Vanhanlinnankatu 1 F 108
FIN-00900 Helsinki
Finland
For more info on giant rats:
E-mail: [email protected]

* Web Author Personal Note: This is one of those cases of misinterpreted behavior by an 'old school' scientist who doesn't believe that rats are capable of play behavior. I've witness this behavior and its no more then the same play behaviors shown by baby domestic rats and is not fighting. As sharp as their teeth are at even this early age, if they were fighting, they would do damage to each other, which there is no sign of. They do tend to be more vocal when playing then other rat species.



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