Research has shown that the cheek pouches of C. gambianus most likely evolved in parallel to those of Sciuridae and other members of the family Muridae.
Gambian rats use screeching as the main form of communication. Gambian rats emit one single short cry which is distinguishable from the longer, varied pitch of African giant pouched rats. Males also use olfactory cues during courtship when they sniff the urine left by female Gambian rats.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Gambian rats are in danger of being overhunted, but due to their rapid generation time the population has not reached the levels of critically endangered or otherwise.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Gambian rats are sometimes considered pests in urban areas where they may infest the sewers. In rural areas, they may destroy farm crops and build burrows in the soil which lead to soil desiccation and loss of plant crops. Gambian rats often inhabit barns and other farm buildings which can lead to property damage.
Negative Impacts: crop pest
The biggest economic impact of Gambian rats is as a source of food in Africa. They are considered rather tasty and are hunted and even raised on farms for their meat. This had led to a significant drop in the population. A smaller industry is the pet industry, although these rats are rather large and sensitive to temperature changes, resulting in a need for high maintenance. In the scientific community, these rats are often used for experiments, and these rats provide a wealth of information on rodent physiology and behavior.
Positive Impacts: pet trade ; food
Gambian rats serve to keep insect populations under control, but also act as transporters of seeds from different plants when they eat the fruits produced. Several parasitic worms inhabit the gastrointenstinal tracts of these rats, but the most prevelant of these are the Strongyloides. A study performed also showed minor prescences of tape worms among other parasites. Other parasites include Xenopsylla cheopis, Aspicularis tetraptera, Ixodes rasus, and Ornithonyssus bacoti. Hymenolepis is usually found in the small intestine while Aspicularis is found in the rectum and colon.
Ecosystem Impact: disperses seeds
Gambian rats are hoarders, and carry as much food as they can fit inside the pouches located on the inner cheeks. They are omnivores and feed on a variety of fruits, vegetables, nuts, and even insects when available. Some common foods include cassava, beans, sweet potatoes, and other roots. Termites have been known to be eaten along with snails.
Animal Foods: insects; mollusks
Plant Foods: roots and tubers; seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Gambian rats are found in central Africa, in regions south of the Sahara desert as far south as Zululand. This includes countries such as Nigeria among others.
Biogeographic Regions: ethiopian (Native )
Gambian rats inhabit a variety of habitats ranging from arid areas to temperate areas, but need some form of shelter to survive. Therefore, they are not usually found in completely open areas, but in areas with cover from hollow trees, rock outcroppings, or burrows made by other animals. They are occasionally known to venture into urban areas and can become pest animals.
Range elevation: 3500 (high) m.
Habitat Regions: terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; mountains
Other Habitat Features: urban ; agricultural
Gambian rats live for about 5 to 7 years in captivity, although some have been known to live as long as 8 years. Life expectancy in the wild is hard to document because of the small size of these creatures and because they are hunted so often by indigenous people.
Typical lifespan
Status: captivity: 5 to 7 years.
Gambian rats are similar in size to the other species of giant pouched rat, African giant pouched rats, and are often confused with this species. Gambian rats have coarse, brown fur and a dark ring around the eyes, in contrast to African giant pouched rats, which have soft, grey coats with white fur on the belly. Their long tails are scaly and they have narrow heads with small eyes. The main physical characteristic of Gambian rats and all Cricetomys in general are their large cheek pouches. These pouches can expand to a great size, allowing Gambian rats to transport massive quantities of food if necessary. Cheek pouches also exist in other families of rodentia, such as the African hamster and members of the subfamily Cricetinae. Males and females are usually the same size, with little sexual dimorphism. Gambian rats can reach sizes up to 910 mm and beyond, including the tail. These rats also have a very low fat content, which may be the cause of their succeptibility to cold.
Range mass: 1 to 1.47 kg.
Range length: 645 to 910 mm.
Average basal metabolic rate: 71 cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 6.024 W.
There are no true predators in the wild that target Gambian rats. Although a few instances have been recorded where a bird of prey or another predator has eaten Gambian rats, they usually band together and are formidable opponents against potential predators. The biggest predator of Gambian rats is humans, the indigenous African population. These rats are considered a delicacy and are often hunted for food.
Known Predators:
Mating in Gambian rats involves the formation of a social pair-bond between one male and one female. The male usually sniffs or licks the urogenital areas of the female before attempting to mount the female. Gambian rats also display peculiar courtship behaviors. The male and female often stand upright and scratch one another, then chase each other until the female is ready for copulation. If the female is not receptive or rejects the male, she bites the male on the tail and back among other areas before courtship behaviors begin.
Mating System: monogamous
Gambian rats are seasonal breeders, usually breeding in the summer. The estrous cycle lasts between 3 and 15 days, while the length of estrus ranges from about 1.4 to 7.8 days. Interestingly, the estrous cycle is often irregular and seems dependent upon many external factors, the environment being one. Other factors include the presence of males, and captivity. Females reach sexual maturity at about 6 months and will typically have about 9 litters annually. The gestation period is approximately 30 to 32 days. Females are also very aggressive when giving birth to a litter.
Breeding interval: Gambian rats breed seasonally
Breeding season: Breeding usually occurs in the summer
Range number of offspring: 1 to 5.
Range gestation period: 30 to 32 days.
Average weaning age: 28 days.
Average time to independence: 30 days.
Average age at sexual or reproductive maturity (female): 6 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 25.7 g.
Average number of offspring: 3.5.
Average age at sexual or reproductive maturity (female)
Sex: female: 158 days.
Gambian rat young are born hairless, with eyes and ears closed. The characteristic long tail does not show substantial growth until about 30 to 35 days. The eyes do not open until about 21 days into development, although the young are completely covered with fur and have open ears at about 14 days. The female provides the most parental care, both as a source of warmth for the naked young and as a source of milk. The female also changes her food preference before the young are weaned, choosing softer foods. The male, on the other hand, shows almost no care to the young. It shows tolerance at best, and will sometimes kill it's young and eat them. This is not seen as often in females. An interesting form of altruism exists amongst females, where a female with a separate litter may take care of a motherless litter.
Parental Investment: altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The Gambian pouched rat (Cricetomys gambianus), also commonly known as the African giant pouched rat, is a species of nocturnal pouched rat of the giant pouched rat genus Cricetomys, in the family Nesomyidae. It is among the largest muroids in the world, growing to about 0.9 m (3 ft) long, including the tail, which makes up half of its total length.[2] It is widespread in sub-Saharan Africa, ranging from Senegal to Kenya and from Angola to Mozambique (although it is absent from much of the Democratic Republic of the Congo, where Emin's pouched rat is present) from sea level to 2,000 m (6,600 ft).[1]
The Gambian pouched rat is sometimes kept as a pet, but some have escaped from captivity and become an invasive species in Florida.[3] In the United States, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) now ban the importation of this species because it is blamed for the 2003 outbreak of monkeypox.
The Gambian pouched rat has very poor eyesight, so it depends on its senses of smell and hearing.[4] Its name comes from the large, hamster-like pouches in its cheeks. It is not a true rat, but is part of an African branch of muroid rodents. It typically weighs between 1.0 and 1.4 kg (2.2 and 3.1 lb).[2] In its native Africa, the pouched rat lives in colonies of up to 20, usually in forests and thickets, but also commonly in termite mounds. It is omnivorous, feeding on vegetables, insects, crabs, snails, and other items, but apparently prefers palm fruits and palm kernels.
Its cheek pouches allow it to gather up several kilograms of nuts per night for storage underground. It has been known to stuff its pouches so full of date palm nuts so as to be hardly able to squeeze through the entrance of its burrow. The burrow consists of a long passage with side alleys and several chambers, one for sleeping and the others for storage. The Gambian pouched rat reaches sexual maturity at 5–7 months of age. It has up to four litters every nine months, with up to six offspring in each litter. Males are territorial and tend to be aggressive when they encounter one another.
A Tanzanian social enterprise founded by two Belgians, APOPO ("Anti-Personnel Landmines Removal Product Development" in English), trains the closely related southern giant pouched rats (Cricetomys ansorgei)[5] to detect land mines and tuberculosis with their highly developed sense of smell. The trained pouched rats are called HeroRATS. The rats are far cheaper to train than mine-detecting dogs; a rat requires US$7,300 for nine months of training, whereas a dog costs about $25,000 for training, but lives about twice as long.[6][7]
In 2020, a Hero Rat named Magawa (2013–2022)[8] received a People's Dispensary for Sick Animals Gold Medal, the animal equivalent of the George Cross, becoming the first rat to receive the award since the charity began honouring animals in 2003. Before retiring in 2021, Magawa detected 71 landmines and 38 items of unexploded ordnance, clearing over 2,421,880 sq ft (225,000 m2) of land in Cambodia, preventing many injuries and deaths, in his 5-year career.[9][10][11][12] Magawa died from natural causes at the age of 8 in 2022.[8]
The Gambian pouched rat is currently being used in experiments at Cornell University to investigate its usefulness in the detection of tuberculosis in human sputum samples.[13] Reports[14] that they are also being used in Mozambique and Tanzania to check tuberculosis test results have proven mildly incorrect: Genetic testing by Watkins shows APOPO's workers are C. ansorgei.[5]
Gambian pouched rats have become an invasive species on Grassy Key in the Florida Keys,[15] after a private breeder allowed the animals to escape in the 1990s.[16][17] Starting in 2007, Florida wildlife officials have tried to eradicate it from Grassy Key, but it was still present as of 2014, and has been sighted nearby on Key Largo and in Marathon, Florida.[16]
This outsized African rodent is also believed to be responsible for the 2003 Midwest monkeypox outbreak in the United States, after spreading it to prairie dogs that were purchased as pets. In 2003, the CDC and FDA issued an order preventing the importation of the rodents following the first reported outbreak of monkeypox. Around 20 individuals were affected.[18]
The Gambian pouched rat (Cricetomys gambianus), also commonly known as the African giant pouched rat, is a species of nocturnal pouched rat of the giant pouched rat genus Cricetomys, in the family Nesomyidae. It is among the largest muroids in the world, growing to about 0.9 m (3 ft) long, including the tail, which makes up half of its total length. It is widespread in sub-Saharan Africa, ranging from Senegal to Kenya and from Angola to Mozambique (although it is absent from much of the Democratic Republic of the Congo, where Emin's pouched rat is present) from sea level to 2,000 m (6,600 ft).
The Gambian pouched rat is sometimes kept as a pet, but some have escaped from captivity and become an invasive species in Florida. In the United States, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) now ban the importation of this species because it is blamed for the 2003 outbreak of monkeypox.
