Dr. Teresa Leslie dissects a dispossessed black rat to remove tissue for DNA testing.
ST. EUSTATIUS–Visitors to last week’s Science Café heard how dry weather has persuaded rats to move into houses on St. Eustatius. Dr. Teresa Leslie of Eastern Caribbean Public Health Foundation reported an increase in complaints and the take-up of rat poison in bait boxes. “It is no longer a rat problem, but a people problem,” she said.
According to Leslie, the appeal of real estate to rats is not limited to Statia. “Authorities in large conurbations such as New York City, Amsterdam and Baltimore have reported a worrisome upswing in rat populations.”
She explained that the bubonic plague in the 14th century was caused by bacteria that were carried by fleas on rats. “Whereas the nobility and the very rich in medieval Europe could escape to the countryside, the poor in their squalid and rat-infested homes were exposed to those fatal flea bites.”
The disease caused an estimated 50 million deaths and remains a killer in certain parts of the world today.
“It was the black rat (Rattus Rattus) that was the vector for the plague and that is the same species that is now house hunting in Statia. Even in sophisticated cities like Washington DC, the demand for rat accommodation has exposed similar social divisions. In Washington, only the rich have the power to rid themselves of these vermin through municipal eradication programmes. The poor remain voiceless,” Leslie stated.
She said that rats on Statia are also downwardly mobile. “They feel particularly at home in abandoned houses, car wrecks and open cisterns. Takeaway suppers are served up from garbage bins, the island dump and beneath forgotten fruit trees. They are picky eaters. Their table manners may not be much, but they achieve a balanced diet by sampling here and there.”
According to Dr. Leslie, more data are required to control Statia’s rat population effectively. She is developing an easy to use app that will pinpoint serious areas of infestation and tip off health officials as to their real estate ambitions.
While Dr. Leslie is taking stock of the black rat’s urban ambitions, Hannah Madden of Caribbean Netherlands Science Institute (CNSI) would like to know more about its rural way of life. She took to scientific “high ground” on Pilot Hill and the Quill crater and has tried to assess the population density of the black rat and fellow rodents such as mice.
“Rats are extremely destructive to our natural habitat,” Madden told the Science Café. “They are perhaps a greater threat to nature than forest clearing or pollution. On Statia, they inflict enormous economic cost and cause damage to agriculture, forestry and other human enterprises.”
Madden had good reasons to choose Pilot Hill and the Quill for her scientific studies. “Pilot Hill is the main nesting site of the red-billed tropicbird. These birds nest within rock crevices along the cliffs and lay only one egg per year. Because of the length of time adults invest in their single-egg clutch, the nests are extremely vulnerable to predators. A treatment plot in the dry forest of the Quill was selected because this area harbours exceptionally high biodiversity compared with other parts of the island.”
The main technique used to estimate rodent density is a simple card with an ink pad, baited with peanut butter, set at 50-metre intervals. Ten of these tracking tunnels were installed in every vegetation type across the island to assess relative abundance.
Analysing images taken by camera traps was another technique used to determine rodent presence or behaviour. Finally, data were collected in plots within each vegetation type to try to determine whether habitat components such as elevation, canopy cover, leaf-litter depth, number of tree- and shrub species are correlated with rodent density.
Madden’s work shows that rats are present throughout the natural areas with trees. This could mean that rats in rural areas use these to nest as well as a source of food.
Much of the research is ongoing and it will be sometime next year before Statia has a clearer picture of the impacts of rural rodents.
According to Madden, one thing is certain. “Beatrix Potter would have found The Quill and the Hill a wonderful inspiration for her furry storybook characters. But these rural rodents are not welcomed by the truly native creatures that have called these areas home for thousands of years.”
Source: The Daily Herald https://www.thedailyherald.sx/islands/76104-rats-feel-more-at-home-on-statia-science-cafe-reveals
View comments
Hide comments