In a bid to address Sri Lanka’s “monkey menace”, a Sri Lankan academic is testing out intrauterine devices (IUDs) on female macaques, to possibly control the population of the species commonly found in the island nation.
There is no official number, but authorities estimate there are roughly three million toque macaques in the country. Some scientists have contested the claim, saying the number is much less, close to five lakh. Last year, the Sri Lankan government resumed issuing shotguns to farmers, amid mounting complaints of serious damage to crops by wild animals. The government’s move came after it scrapped an earlier proposal to export monkeys to China that was widely criticised by conservationists.
The ongoing experiment seeks to adapt intrauterine devices (IUDs), an increasingly popular long-term contraception method for humans — upon insertion into the woman’s uterus, an IUD prevents pregnancy — to the monkey species. Use of the device on animals is only at an experimental stage, according to Prof. Ashoka Dangolla, a senior veterinary scientist attached to the University of Peradeniya, in Sri Lanka’s central Kandy district, who is leading the experiment.
“We fit the IUDs in eight monkeys about three months ago and are monitoring their response. The next stage will require introducing sexually mature male monkeys. If the monkeys mate, we would be able to study if the females get pregnant. The third stage would be a field trial,” he told The Hindu.
Prof. Dangolla has been involved in various community initiatives to tackle the monkey population for some 15 years now. “It takes many years for [birth control] surgeries in male monkeys to begin impacting the population,” he said. For his ongoing experiment, he used regular IUDs sourced from India, after resizing them locally for use on the monkeys. “To complete the experiment, I would need more support,” he said, adding that there is currently little government backing for his experiment.
Meanwhile, experts remain sceptical of birth control measures on animals, that have been tried in other contexts. Wolfgang Dittus, a renowned primatologist based in Sri Lanka, who has been studying the island’s toque macaques for over half a century contended that contraception takes many years to affect population reduction, and that it is neither desirable nor practical to capture and treat all monkeys.
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While noting that the ongoing experiment was of interest, he said similar experiments on free-ranging monkeys in Asia have shown that it is effective only if contraception is combined with a legally imposed strict ban on feeding wild monkeys, since access to human food fuels monkey survival, birth rates, immigration, and the resulting population growth.
Further, reducing the monkey population will not necessarily reduce the human-monkey conflict, in his view. “Sri Lanka needs to think out of the box, implement new strategies for quality living. Issuing guns to farmers to kill wildlife is obviously not a cogent solution to any current challenges. Plantations and crops can be protected from loss to wildlife, but it requires a receptive culture for implementing novel methods of doing agriculture in coexistence with nature,” Mr. Dittus said.
