Mongoose 'dem: Trouble in the Territory

March 5, 2006 — While Virgin Islanders continue to disagree on the plural of mongoose (arguments exist for mongooses, mongeese and even "mongoose 'dem"), biologists and natural resource officials have agreed on one thing: Mongooses are an unwelcome problem that may be increasing on some islands.
Neither the Department of Planning and Natural Resources nor the V.I. National Park Service has taken population counts of the animals. Resource officials say anecdotal evidence on St. John suggests the mongoose population is stable or increasing slightly. On St. Croix the numbers seem to be steadily increasing, while on St. Thomas the evidence is inconclusive: biologists and officials currently disagree on the growth or decline of mongooses.
Population controls
On St. Thomas, DPNR Media Relations Officer Jamal Neilsen said the department does little to protect or control the population of mongooses. However, the Fish and Wildlife Division does monitor the location and behavior of the animals.
Neilsen said he believed the population had increased a bit in the past several years. "Maybe they wised up and stopped crossing the street," he joked.
In a much more serious tone, Neilsen said mongooses are a real "nuisance," but that DPNR would not do anything about the population until, or unless, the animals become a hazard to humans.
On St. John, the park service, in conjunction with the U.S. Department of Agriculture, is continuing efforts to control the mongoose population. Rafe Boulon, chief of resource management for the park service, said those efforts started in 2002 with the baiting and euthanizing of mongooses in select areas, including popular tourist spots like Trunk and Cinnamon bays and other areas where turtles lay eggs.
The number of mongooses the park service catches each month varies based on the animals' breeding habits, but Boulon estimates the park service catches "a couple hundred" every year. "It makes a difference on the turtle beaches," he added.
The program's goal is not to eliminate mongooses — a nearly impossible task given the high population numbers, their breeding habits, the abundance of available food and the size of St. John — but to simply reduce the population to "acceptable levels" and then maintain those levels on park lands.
According to a 2002 invasive species environmental assessment report by Boulon, "acceptable levels" are specified as ones in which mongooses "produce minimal or no damage to park resources or threats to visitor and employee safety."
Boulon also said a virus in the mid-'90s may have had a large negative impact on the mongoose population on St. John, but the park service has been unable to verify whether there ever was such a virus.
Anecdotal evidence, including the number of mongooses trapped and frequency of sightings, suggests the population on St. John is "stable or maybe increasing slightly," Boulon said, but the park service has no plans to change the population reduction program.
Meanwhile on St. Croix, evidence suggests the mongoose population is growing, said William Coles, DPNR's chief of endangered species and environmental education on St. Croix.
"Anecdotally, I can say five years ago it was hard to find a mongoose; you might see one on a route in a day. Nowadays, on the same route you might see 10," he said. Coles also said a lot more chickens are dying, which is possible evidence of more chicken predators, such as
mongooses.
How they got here
According to Boulon's 2002 report, sugar cane plantation owners introduced mongooses to the Virgin Islands in the 1800s to control the population of tree rats, another non-native animal.
At first, farmers believed the rat population was in decline, so they imported more mongooses. Several years later, however, sugar farmers discovered that mongooses are diurnal (active chiefly during the day) and cannot climb trees. Conversely, tree rats are nocturnal (active at night) and sleep in trees during the day. Consequently both populations flourished, and rats and mongooses are still a problem more than 150 years later.
Thriving population
Mongooses have no natural predators in the Virgin Islands, so the population can grow rapidly if it is left unchecked. Mongooses breed two to three times each year and have litters averaging three babies.
They generally live in ground holes or under rocks, venturing out to eat and hunt. The small Indian mongoose is a long, thin, usually dark-brown animal with short fur, ranging from 1.5 to 3 feet in length. The animals generally have a lifespan of about four years.
According to Fish and Wildlife biologist Renata Platenberg, mongooses have a plentiful food source on the islands because they will eat just about anything. The animals, found originally in Africa, Asia and Southern Europe, are not afraid to enter human areas to munch on scraps and trash in dumpsters. They also eat plants and fruit; bird, turtle and snake eggs; and rats, chickens and snakes.
Environmental impact
According to the 2002 environmental assessment, high numbers of non-native animals "pose a very large threat to the native natural resources, long-term resource management programs of the park, and visitor health and safety."
Mongooses are a problem for several reasons, including their aggressive behavior against other animals such as turtles (and their eggs), chickens, snakes and their destruction of plant life.
The aggressive critters are blamed for eliminating entire species from the Virgin Islands, including the St. Croix racer snake in the 1970s, Platenberg said.
Mongooses are also blamed for wiping out the ground lizard from St. Croix and the Puerto Rican racer snake on St.
Thomas and St. John (although the snakes still live on Water Island).
A 2005 biology paper on reptiles of the Lesser Antilles by Robert Powell and Robert W. Henderson stated, "If mongoose are present on an island, racers have usually been extirpated [eliminated]; if the mongoose is absent, racer populations are healthy."
Another threatened snake species, the slippery back skink snake, is now only living on offshore cays that do not have mongooses.
Islands are of special concern with introduced species for several reasons, foremost being the limited amount of land for animals in which to cohabitate.
In his 2002 report, Boulon wrote, "Of the 484 recorded animal extinctions since 1600, 75 percent have been island endemics."
The only option now, really, is to work on educating the public about mongooses and try to prevent other invasive species from coming into the territory.
Education efforts
As an introduced species, Coles said, mongooses are highly threatening. "The U.S. government will not allow live females into the United States," Coles said. "That's how dangerous they are."
The only good thing Coles can say about mongooses is that since they have never been exposed to rabies, they do make good test animals. The Centers for Disease Control and Prevention in Atlanta comes to the Virgin Islands periodically to collect male mongooses for rabies vaccine testing, Coles said.
For now, DPNR is working with the Department of Agriculture to try to prevent other invasive species from entering the territory.
"The best thing we can try to do is keep these invasive species away," Coles said. DPNR's methods include educating the public and working with port authority employees to help them recognize potential threats.
"It just takes one person bringing something sick in, and wham! You have a million dollar headache," Coles said.
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