Alarming change in Rhesus Macaque sex ratio

Hyderabad:The monkey menace has thrown up an unexpected problem. A top national research lab – the National Animal Resource Facility for Biomedical Research – according to sources, has requested that it needs 60 bonnet macaques for research purposes. But these monkeys have become hard to find thanks to the monkey menace that plagues Telangana on account of the increasing number of rhesus macaques whose numbers are growing rapidly.

“There was a time before the 1990s when the rhesus monkey numbers were low. But this has changed. These monkeys are aggressive, and have been driving away the bonnet macaques, and as a result, the bonnet numbers have gone down as they have fewer and fewer spaces to live and breed in,” a forest department official said.

Sources said the ball was thrown back into the lab’s lap asking it to provide information on where bonnet macaque troops can be found. Once this is known, then a long process would start of seeking permission from the government of India for their capture. Irrespective of what purpose they are needed, this will be a hard task as bonnets are now a protected species under Schedule I of the Wildlife Protection Act that affords the highest level of protection for wildlife under Indian laws and prohibits their capture.

“The thing about bonnets is they are excellent candidate species for medical research for human benefit, particularly with respect to non-communicable diseases such as diabetes. They are also the choice of research animals to study reproduction issues that can help humans,” a scientist familiar with the use of these monkeys in research labs explained.

The real problem that needs addressing before anything can be done about the bonnets is to find out why the rhesus numbers are growing, according to Dr V. Vasudeva Rao, a specialist in vertebrate agriculture pest studies and former professor at Prof Jayashankar Telangana State Agriculture University.

“The normal male to female sex ratio of rhesus is 1:1.27, but we are finding that in Telangana this is getting skewed to 1:4.7 and up to 1:6.7. This is an alarming situation. To control the monkey menace, an urgent understanding is needed on why more females are being born, as more females mean more potential for breeding and increasing numbers of the species,” Dr Vasudeva Rao said.

Of Telangana’s 33 districts, the menace due to marauding rhesus macaque troops is now endemic to 11 districts listed as ‘high occurrence’ of the monkey menace, followed by 9 ‘moderately’ affected districts, while 13 are listed as ‘low occurrence’ districts.

For instance, the monkey menace problem is 100 per cent — as in all mandals of a district — in Jangaon and Mulugu districts, and in Mahbubabad, Jayashankar Bhupalpally, Khammam, it is 70 percent.

At least 240 mandals have severe monkey menace problems, he said. A realistic estimate of the rhesus population is that they could be between 50,000 to 70,000 of them in the state.

Incidentally, towards the end of 2021, the then BRS government, had initiated a quick survey of rhesus macaques with the agriculture department as the nodal agency. But the numbers that came up, reportedly ended up being unrealistic with some officials putting the rhesus population at a whopping 30 lakh to 50 lakh.

No further action was taken on these ‘findings’ once it was pointed out to the government that these numbers cannot be even remotely correct. The question raised was if there were so many monkeys, and if each consumed just around 200 grams of food every day by raiding crops, then nothing would be left for farmers.

Even at the lower estimate of 30 lakh, it meant 6 lakh kg of crop lost in monkey raids a day. “But the farm produce figures told a different story and nothing more was heard of the survey again,” a source familiar with the entire exercise said.