Gambian Pouched Rats: Exotic Pets and an Invasive Species
Interesting and Helpful Animals
Gambian pouched rats are interesting animals. They are sometimes kept as exotic pets and can become very affectionate, although the temperament of individual animals varies. They are also intelligent and playful. In Tanzania, they’ve been trained to detect land mines due to their excellent sense of smell and the fact that their bodies are too light to detonate the mines. They've also been trained to detect tuberculosis in human sputum samples.
Gambian pouched rats can grow up to three feet long (including their tail) and can weigh three to four pounds. They are rodents, but they belong to a different family from the common wild and domestic rats. Like hamsters, the animals have pouches in their cheeks to store food. They live in Africa south of the Sahara and are also known as African giant pouched rats.
Unfortunately, a group of animals escaped from a breeder in Florida and colonized an island called Grassy Key, where they’ve become an invasive species. In addition, in 2003 they may have played a role in an outbreak of monkeypox in the United States.
Ben: A Young Gambian Pouched Rat
The Animals in Their Native Habitat
The scientific name of the Gambian pouched rat is Cricetomys gambianus. Strangely, although the rodents are common animals and are caught for food by many people, not very much is known about their lives in the wild. They may live as solitary animals or in a colony. Research suggests that the males are more likely to be solitary while the females and babies are more likely to live in a colony.
The animals are found in a variety of habitats that offer some form of shelter, such as areas with trees, rocky outcrops, or more open areas that contain burrows dug by other creatures. The burrows often become a network of tunnels once the rodents move in. Pouched rats are adaptable animals and migrate to other areas if these are more desirable or if their original habitat is damaged.
The animals are usually nocturnal in the wild and have an omnivorous diet. They eat plants and plant parts, insects, and other small invertebrates. They collect food in their pouches to take back to their burrows and are great hoarders.
The Gambian pouched rat is sometimes confused with its relative, Cricetomys emini, which is known as Emin's pouched rat. This species is also kept as an exotic pet. It tends to be a smaller and more slender animal. There are also some coloration differences between the two species.
Gambian pouched rats are prolific breeders. Females can have their first litter at around five months. It's reported that in the wild they have from four to nine litters a year. The gestation period is thirty to thirty-two days. The babies are born with their eyes and ears closed and have no hair. A litter consists of one to six pups but generally contains four babies. The animals live for about six to eight years.
Pan: An African Giant Pouched Rat
Although Gambian pouched rats are bred in captivity, they aren't domesticated animals. It takes a long period of selective breeding to fully domesticate a wild animal. The rodents need to be socialized and trained from a very early age. Daily handling and attention is very important, even when a pup has come from a careful breeder who is trying to produce good pet animals.
Prospective owners need to have time to care for their pets. The animals can't be left in a cage continuously. When they are let out of their cage, they should stay out for a long time. If they aren't petted regularly and played with every day they are likely to quickly lose their friendliness and confidence.
Thistle: A Pet Animal
Cage, Fun, and Food
Pouched rats like to run, jump, and climb. Their cage needs to be large and have lots of toys arranged at different levels. An animal must be able to move rapidly around the cage, preferably by different routes. The pet will destroy many of the toys, so a replacement supply needs to be available to keep the animal entertained while it's shut in the cage. Of course, all the toys must be safe to chew. Pouched rats have a low body fat content and get cold quickly, so they need to be kept warm.
Animals kept as pets eat a wide variety of vegetables, fruits, nuts, seeds, grains, and meats, as well as eggs. A pet's breeder should be consulted about a suitable diet for a particular animal. The rodents like to dig into the litter at the bottom of the cage and store food there as well.
Gambian pouched rats usually back into a corner of their cage to urinate and defecate. Owners say that the animals can be potty trained, using a dish partially filled with water as a toilet. Their litter still needs to be cleaned regularly because it may contain decaying food.
An Emin's Pouched Rat Using a Toilet
Cautions and Potential Problems
Gambian pouched rats have large and strong teeth. They love to chew and can be very destructive. Although pet animals are often docile, it's important to realize that they could give a painful bite if they wanted to. As with any exotic pet, owning a pouched rat is a much more demanding job than owning a domesticated animal. The pups are cute, but someone considering buying one needs to do a lot of research about the responsibilities of owning this pet. They also need to think very carefully about the advisability of welcoming a pouched rat into their home.
Land Mine Protection
APOPO is an organization started by a Belgian man named Bart Weetjens. His goal is to train Gambian pouched rats to save human lives by detecting land mines and tuberculosis. The rodents are trained with a clicker, just as some pet dogs are trained. The animals hear a click from the clicker and receive a food reward to reinforce their behavior when they perform successfully. Bananas and peanut butter are favorite treats. The animals are known as HeroRATS.
APOPO is based in Tanzania. Both land mines and tuberculosis are big problems in some parts of Africa. Gambian pouched rats were chosen as helpers because they are trainable, are often friendly, and have a great sense of smell. They can detect land mines in both metal and plastic cases. They also live naturally in the area and are long lived, inexpensive to care for, and resistant to many local diseases.
While surveying an area for land mines, a pouched rat is attached to a harness which is in turn attached to a rope by a leash. The rope is suspended in the air by two human handlers. The rodent is trained to scratch the ground when it detects a mine. The area is then marked by the humans and the mine is later removed. According to the APOPO website, two HeroRATS can survey 300 square meters of land in one hour, whereas two manual deminers using metal detectors would take two days.
Pouched rats that are trained to detect tuberculosis enter a cage and sniff a series of holes that have sputum samples underneath. If an animal detects TB it keeps its nose in the hole for at least three seconds and also scratches the hole. APOPO says that the rodents can sample 40 sputum samples in seven minutes instead of the full day needed by a lab technician. In addition, the animals detect cases of TB that are missed by humans.
A Pouched Rat Being Trained to Detect Land Mines
An Invasive Species
Despite their ability to become delightful pets and their usefulness in helping to save human lives, in Florida feral Gambian pouched rats have become a potential problem. The situation is thought to have begun when a pet breeder released pouched rats—reportedly six to eight individuals—into the wild on Grassy Key (or when the animals escaped). The rodents reproduced rapidly. There were serious concerns that they would damage the habitat, compete with local species, and migrate to other environmentally sensitive areas.
Beginning in 2007, poisonous bait was distributed as food. In 2009 the pouched rat population seemed to have disappeared. In 2011, however, reports of live animals appeared. The reports continued into 2012. Another attack was mounted. Once again it seemed like the battle against the animals was succeeding, but in 2014 it became obvious that the giant rat population hadn't been eliminated.
There are fears that the pouched rats are competing with endangered native wood rats. Officials are very concerned about the animals reaching the mainland and the Everglades. Gambian pouched rats have damaged food crops in Africa and might have a serious effect on agricultural crops on the U.S. mainland. New attempts are being made to remove the animals, which include a trapping program.
An Emin's Pouched Rat Eating Cookies
In 2003, it was suggested that Gambian pouched rats were implicated in an outbreak of monkeypox in the United States. Monkeypox is a viral disease related to smallpox, although it's generally—but not always—less serious. The virus is often carried inside rodent bodies.
It was discovered that most of the people who became ill with monkeypox had come into contact with infected prairie dogs. It's thought that an animal vendor placed cages containing imported and infected Gambian pouched rats and other infected rodents close to cages containing prairie dogs. This allowed the virus to pass to the prairie dogs. CDC testing showed that one of the pouched rats and several of the other rodents contained the virus in their bodies. Humans may have become infected when they handled the prairie dogs.
Despite the potential problems caused by Gambian pouched rats, I think they are lovely animals. Like any non-native species, though, they are best appreciated in their original environment and habitat where they are endemic.
© 2012 Linda Crampton