The Government’s recent plans to deal with crops being damaged by crop raiding animals have drawn mixed reactions from experts.
Crop raiding by wildlife is when wild animals damage crops by feeding on or trampling on them, which contributes significantly to food insecurity, especially in cash-strapped Sri Lanka.
According to a report by the Hector Kobbekaduwa Agrarian Research and Training Institute (HARTI), coconut is the worst-affected crop due to crop raiding, followed by paddy, vegetables, corn, and bananas. In terms of crop raiders, the toque macaque remains dominant, followed by wild boar, elephant, peafowl, giant squirrel, and porcupine.
The report estimates the financial loss caused by crop damage due to wild animals as Rs. 30,215 million ($ 87.5 million) in the first half of 2022. This included the destruction of 144,989 MT of 28 food crop varieties, as per the report.
HARTI has also revealed that giant squirrels and monkeys destroy some 107 million coconuts annually, and that 93 million coconuts had been destroyed in the first half of 2022.
The Government has so far mulled several control measures against destructive wild animals, including culling, sterilisation, and air rifles, among others.
In its most recent attempt at a solution to these wild animals that are considered agricultural pests, the Government is now considering the export of around 100,000 toque monkeys to China, a move that has raised concerns from environmentalists, who have pointed out that Sri Lanka’s legal provisions prohibit the export of animals.
Culling and culture
Speaking to The Sunday Morning, University of Peradeniya Faculty of Agriculture Senior Professor Buddhi Marambe noted that these wild animals had been recorded to affect crops, especially in rural areas. “This has been the case for a long period of time, but people are now becoming concerned because it looks like it is not only the crops that are being attacked, but households as well.”
However, Prof. Marambe noted that while in many countries population control of such animals was done by culling, this would be a difficult task to carry out in Sri Lanka, given the cultural and religious factors in play.
“Killing is one of the main ways of population control in many countries, but in a country like ours that has not been the practice because our culture and religion has ensured that killing of animals has not been approved, despite the fact that there are lots of negative impacts of wild animals on agriculture.”
According to the Professor, at a national-level meeting of experts held last December at the HARTI to discuss this issue, all had been in agreement that population control may have to be considered. “However, what methods to use were not discussed,” he noted.
Prof. Marambe also cautioned that population control should not be taken as a measure of eradication, but to maintain it at a level where the carrying capacity would fit into a given ecosystem, stressing that any approaches should be science-based.
Since most of these animals are endemic to Sri Lanka, managing their populations was important, he said. He also noted that the experts at the meeting had recommended identifying areas where different animals had become a menace or where their negative impact became most significant and to adopt the most prudent control measures with the support of subject matter experts.
While there have been attempts several years ago to try out sterilisation as a solution, the lack of adequate monitoring thereafter to identify the success of the programme has posed a challenge. However, he noted that veterinary scientists who were capable of handling such scenarios had expressed confidence that this method of population control could be executed.
With the increasing impact, the current scenario has put the Government in a difficult spot due to the social pressure from both sides of the issue, he noted, stressing however that striking a balance was crucial and that there should be some compromise.
Not easy to prevent
Meanwhile, Centre for Conservation and Research Chairman Dr. Prithiviraj Fernando too agreed that crop raiding was not easy to prevent. He noted that population control measures were sometimes not practical, for instance translocation simply transferred the problem to a different area, providing only temporary relief.
“For any species, if that species is very populous, that’s a good thing. But in the case of these particular species, something has to be done, but what can be done is the question because there are no easy solutions. To control the population of these animals is extremely difficult.”
Smithsonian Primate Biology Programme Director Dr. Wolfgang Dittus, who has undertaken extensive studies on toque macaques in Sri Lanka, also pointed out that culling and translocation were not permanent solutions or ones that were very effective, noting that various deterrence methods were being used in other countries, such as taking measures to prevent people from contributing to monkeys becoming pests by allowing them access to food sources.
He also critiqued popular reports, noting that no surveys had been done of macaque densities on plantations (e.g. coconut) and that claims of islandwide macaque numbers in the media were not empirically substantiated and ignore crop loss owed to insects, weather, poor storage, transport, and human mismanagement. “Recommendations to reduce crop loss require education, effort, and investment that so far have been ignored and not implemented. Instead, emotionally charged misinformation and popularised remedies to kill have swayed influential opinions,” Dr. Dittus said.
Study on human-monkey conflict
In a study done on human-monkey conflict in Sri Lanka, Dr. Dittus has found that “the majority (80%) of people desired a translocation of the troublesome monkeys from their properties to protected areas, which is impractical. Few (<1%) openly wanted monkeys destroyed. While a traditional reverence for monkeys provides a solid basis for science and media-based education, it also contributes to the feeding of monkeys and consequent unnatural population growth, and enhanced Human-Monkey Conflict (HMC).”
The study concludes that “a combination of a feeding ban, possibly contraceptive intervention at localised HMC trouble spots, and extensive education may be the only benign alternatives to the destruction of wild primates by a powerful minority.”
The study explains that macaque populations can grow rapidly at localised sites near municipal garbage dumps, temples, tourist attractions, roadside fruit and vegetable stands, picnic sites and hotels, and when this growth occurs near crops, the macaques are enticed to feed on them. According to Dr. Dittus, this has two negative consequences: firstly, it pits monkeys and people into conflict and secondly, at such localised sites, macaques are very conspicuous and give people the wrong impression of many macaques nationwide. In natural areas away from humans, however, macaques are rare or even absent, he stressed.
The study therefore posits: “On ecological principles alone, it is predictable that if these artificial sites were to be eliminated, the population of crop-raiding monkeys and their prevalence on human properties, too, would be reduced substantially over time. In a similar vein, the elimination of government incentives to grow crops near protected areas would help to reduce HMC; a commonsense approach that applies to human-wildlife conflicts anywhere.
“Crops can be shielded from monkeys by buffer zones. In Sri Lanka, the forest-dwelling toque macaques shun crossing open ground: this reluctance can serve in the defence of crops.”
Dr. Dittus shared that farmers in Sri Lanka were also taking measures to protect crops against monkeys, although this required further research: “In certain banana plantations they have developed baskets surrounded with chicken wire to protect the plants. In the upcountry in Nuwara Eliya, farmers put netting over the crops, and when monkeys get caught in the net, that is such an unpleasant experience that monkeys learn not to go near vegetable plots with this netting. And monkeys learn very fast; they are very clever.”