Full Thread: Invasive Species
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Old December 12th, 2008 #5
Alex Linder
Join Date: Nov 2003
Posts: 45,338
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Alex Linder

The Giant Rats are in the News again.


Here in the Florida Keys, as with much of South Florida, we are always dealing with invasive exotics from the Brazilian-pepper tree to iguanas to batfish. Now we have another to add to this list. The African Gambian pouch rat.

This cute invader, which can get up to 9 pounds has made Grassy Key its home. Some biologists and conservationists in the Keys insist it must be eradicated before it increases its range and begins to cause problems for native species living in the Florida Keys. Although nobody is sure how or why the rat was released on Grassy Key, biologists are saying the animal could be devastating to the Florida Keys' ecological system.

These omnivores eat almost everything and could compete for food with endangered species such as the silver rice rat and the endangered wood rat. They might also carry diseases and could be eating bird eggs. A greater threat, some say, is if the pouch rat makes it to Key Largo. It would not be difficult for it to then reach the Florida Everglades. "There's no telling what would happen if they made it to the mainland," biologist Randy Grau said.

Grau, a biologist for the Florida Fish and Wildlife Conservation Commission, is an advocate for stopping them on Grassy Key. Grau believes it could be difficult for the rats to make it across the long bridges to Key Largo and Big Pine Key. "But they could get in the back of a truck and make it that way," he said. It is believed Grassy Key is the first documented breeding population of African Gambian Pouch Rats in the United States. So far, nobody has stepped forward to eradicate the rat. Government agencies, well you know. Chris Bergh, chairman of the Florida Keys Invasive Exotic Task Force, said the exotic rats could harm rare and protected species. Yea, well so can (do) all the feral cats . The rats get their names because they have pouches in their cheeks would eat a variety of plant materal. "If the rats eat the fruit, it could prevent plants from spreading as they should," Bergh said. What he forgets to add is they might also spread seeds that are not getting spread in the same manner now. Another fear is that since the rats are so big they may not have any natural predators. Well the expansion of the endangered saltwater crocodile needs more prey.

Neil Perry, who is writing a thesis for his Texas A&M master's degree while studying in the Keys, said the rats are probably too big for birds of prey to eat. Maybe the truth will be that there will be an increase in native preditors due to an increase in viable prey. Another thought, natives such as the previously mentioned crocks and bald eagles and redtailed hawks might have a larger presence with the added food available. Perry is studying the population of the silver rice rat and the Lower Keys marsh rabbit in the Keys. He admits that feral cats, which are predators of the endangered species Perry is studying, don't mess with the Gambian pouch rat. Imagine what would happen if they actually helped some natives survive.

Connie Faast, who lives on Grassy Key, had the giant rats living under her house. One night, she said, she heard loud screeches in the street. The rats were fighting. "Two cats were on the side of the road just watching the rats," Faast said. The male pouch rats are aggressive when they encounter one another. I wonder if they are as loud and do as much damage as 2 tom cats fighting under your window. These rats are well known in the pet industry and have a reputation as being very friendly, intelligent and do well in a domestic situation.

Rumor has it that eight pet rats were released five years ago, one male and seven females. The rats can have up to four litters every nine months, with up to six offspring in litters. There is no telling how many of the rats are living on Grassy Key now. One resident states recently she has not see as many of the big rats. Faast also said she has not seen as many rats recently, but she knows they are still there. "Ever since we started trapping under my house, they haven't been back," Faast said. She thinks the rats are too smart to go to a place where they were previously trapped.


The animals have a sense of smell so uncanny that they have been studied for use in detecting tuberculosis and in sniffing out land mines. From 2003: "The first batch of 12 rats trained to detect land mines are now at work in neighboring Mozambique and so far have sniffed out 20." Today these plucky creatures are helping clear Mozambique of land mines from its civil war. Dogs have been trained as land-mine sniffers, but if they step on the mine, no more dog; three-pound Gambian pouched rats are too light cause detonation. Male African Gambian Pouch Rat Sniffing for ExplosivesThese rats have exceptionally powerful noses, being able to sense the slightest trace of the nitro compounds in explosives. And while dogs will sniff for mines for a while and then get bored and want to frolic, Gambian giant pouched rats possess noble clarity of purpose: So long as they are given a chunk of banana for each mine found they will tirelessly, single-mindedly spend every waking hour searching for another.

Dec 15, 03: The giant pouched rats that have been trained to sniff out land mines in Africa are now learning to detect tuberculosis bacteria in human saliva with the help of a grant from the World Bank. The World Health Organization estimates that deaths from tuberculosis will rise from 2 million this year to 8 million by 2015.

The rat can sniff 120-150 human saliva samples in lab dishes in 30 minutes compared to the day's work it takes for a human technician to analyze 20 samples. The rat stops in front of samples that smell like TB and waits to be rewarded but walks past samples where TB is not present.


When an outbreak of monkeypox, linked to pet prairie dogs and Gambian pouched rats, was confirmed in June 2003, the Centers for Disease Control (CDC) and the Department of Human Health and Safety (HSS) issued a joint order that banned the import of several African rodents and also the transport, sale or release of pet prairie dogs. At the time, it was clear that although the outbreak was quite mild, it was potentially serious enough that the exotic pet trade was going to come under close scrutiny. Since there has not been any local outbreaks it can be assumed this population is free of the disease.


Scientific name - Cricetomys gambianus What is an African Gambian Pouch Rat? African Gambian Pouch rats, also known as the African giant pouch rat, resembles a hamster in having a storage pouch inside of each cheek. When the pouches are full it gives the pouch rat an absolutely adorable, yet comical face.

Their body colour ranges from shades of gray to brown, the belly being considerably paler and their feet are almost white. There are some pouch rats turning up spotted with white or with a white stripe running across their shoulders, but these are still very rare. The pouch rats have large ears (which lends to their comical appearance) that are covered in very fine hairs, giving them an almost hairless appearance. The first two thirds of the tail is dark gray with the final third (to the tip) is white to off white and covered with the same fine hairs as the ears.

The pouch rats homeland ranges from Senegal to Central Sudan and down to South Africa. These rats dwell in the forest and thickets. For shelter they often use natural crevices and holes, termite mounds, or hollow trees but when need be they can dig their own burrows. In the wild pouch rats are generally nocturnal, but do forage during the day. When they forage during the day they behave almost blind, relying heavily on their keen noses and hearing to get around. In captivity they readily become used to their owners routine.

POUCH RATS AS PETS: Generally they are solitary and shy in the wild making them naturally non-aggressive on open ground, but they can be very protective of their den. In captivity they are very intelligent and have the ability to bond/show deep affection to their human companions. However do take into considerations that they are not a domestic animal, they are a captive bred exotic that has the ability to display some of its wild traits.

DIET: The Pouch rat is an omnivore, their diet in the wild consists of insects, snails, nuts, seeds, and fruit. In captivity they are relatively easy to feed. A good parrot mix (remove chili peppers), which then can be supplemented with mixes nuts (no salt), dry dog food or Omnivore dry diet, rodent blocks, monkey biscuits, dried fruits and raisins. On a daily basis they require about half a cup of fresh fruit/vegetable matter. For treats one can offer cooked pasta, whole grain breads, cooked eggs, and even a little yogurt. Now remember because of their wonderful cheek pouches they can carry a large amount of food - so they do on the occasion empty out their food dishes only to store it someplace else. Fresh clean water daily is a must - one can also offer them a good rodent multi - vitamin to their water.

With lots of love, daily handling, good diet and care Pouch rats can live a long happy and healthy life.

Lifespan in captivity - average is 8 years but some have been known to live up to 10 years. Sexual maturity is 5 to 6 months. Males can be neutered.