KUALA LUMPUR, Oct 23 ― Pig-tailed macaques may be considered a nuisance to some but research has shown that the monkeys were a highly effective form of natural pest control against rats in Malaysia’s oil palm estates.
A report released in the scientific journal Current Biology said that scientists in Malaysia were “stunned” to discover the rate at which the monkeys, which usually eat fruit or the occasional lizard or birds, were regularly killing and eating rats in oil palm plantations.
Rather than being pests, the primates’ presence has eased crop losses by reducing the number of an even bigger pest ― rats ― so much so that they have eliminated the need for chemical pest control, UK-based news outlets Telegraph and The Guardian reported.
Universiti Sains Malaysia senior zoology lecturer Nadine Ruppert, who co-wrote the report of the study, said that she was stunned at the macaque’s propensity for rats as she did not expect them to hunt these relatively large rodents or that they would even eat so much meat.
The study monitored macaques between January 2016 and September 2018 in plantations around Malaysia’s Segari Melintang forest reserve.
Each of the monitored macaque troops, each with an average of 44 monkeys, killed around 3,000 rats each year. Anna Holzner of the University of Leipzig said that the monkeys hunted the rats by uncovering cavities in oil palm trunks where rats sheltered during the day.
Rats are estimated to damage an average of 10 per cent of oil palm crops by eating the fruits, compared with the macaques that damage around 0.54 per cent of the palms.
The report concluded that overall, the rat-eating monkeys helped save Malaysia’s palm oil crops and advised palm oil farmers to protect the macaques and to set up corridors for them to reach distant areas of plantations.
Southern pig-tailed macaques are listed as “vulnerable” by the International Union for Conservation of Nature, but are regularly killed by palm oil plantation staff who believe them to be pests.
Anja Widdig said that she hoped the report would encourage plantation owners to protect primates and their natural forest habitat instead of viewing them as pests in plantations.
“This ultimately can lead to a win-win situation for both biodiversity and the oil palm industry.”
Malaysia, which provides around 30 per cent of the world’s palm oil needs, produces some 19.5 metric tonnes of palm oil per year.
However, oil palm plantations are controversial due to its environment effects on forests and wildlife.
Large areas are often burned and cleared to make way for the plantations, releasing large amounts of carbon dioxide into the atmosphere, and also creates habitat loss.