Singapore is at a crossroads in its management of wild monkeys, and to cull or not to cull these native creatures has emerged as a key question.
The good news is that public feedback on monkeys, mostly complaints and related to safety and nuisance concerns, fell sharply from 1,860 instances in 2013 to just 750 last year.
But that has stirred controversy over the cause, given that there has been extensive culling of the animals recently.
In 2013, the Agri-Food and Veterinary Authority (AVA) killed about 570 monkeys, about a third of the estimated population at that time.
A similar divide over culling, which is the selective killing of animals to manage their population, has also emerged during debates over how best to deal with close encounters of the unwanted kind between humans and wild dogs and wild boar. As development continues apace to cater to a growing population, such encounters are set to grow.
When it comes to monkeys, the AVA's stance is that it carries out humane euthanasia of the animals as a last resort, and targets aggressive and nuisance-causing monkeys for safety, in response to public feedback.
It has also explained that relocating long-tailed macaques - the species of monkey in question - is not feasible as that simply transfers the problem from one estate to another.
Some residents in areas like MacRitchie and Bukit Timah, who previously had run-ins with the animals, told The Straits Times that they have seen significantly fewer monkeys in their neighbourhoods.
But animal welfare groups and monkey researchers in Singapore, as well as some of those residents, challenged the link between the culling and the plunge in complaints. They pointed to other possible reasons, such as the installation of monkey-proof bins in the estates.
In some areas, there were campaigns to get people to stop feeding the monkeys, which draws the primates to residential areas in search of food.
The Animal Concerns Research and Education Society (Acres), an animal welfare group, set up a hotline in 2013 for people to give feedback and get tips on how to prevent human-monkey conflicts.
Acres also piloted "monkey-herding" operations at several condominiums, working with the condominium guards to herd monkeys off residential premises.
Acres has also wielded the findings of a survey it commissioned in January this year to argue that only a minority of people support culling.
The survey, by consultancy firm Millward Brown Singapore, polled 600 Singaporeans on animal protection, asking, among other things, whether they thought monkey culling should be allowed. That question has been criticised by some as "leading".
Another criticism is that the survey was done online and respondents could choose to remain anonymous.
That being said, 42 per cent of those who responded wanted culling to be banned. Only 13 per cent supported culling, while the rest - 45 per cent - sat on the fence.
Test alternative methods
WHEN it comes to the dramatic fall in the number of complaints about macaques, it is likely that both culling and other methods played a part.
But it is unclear how effective each of the methods has been.
With the monkey population and the number of complaints at a low, there is no time like the present to devise ways to assess each of these methods in turn.
One way to do so is to have a temporary moratorium on culling and to embark on a rigorous evaluation of alternatives.
The aim should be to see if more humane methods that do not involve killing the animals can achieve the same ends, and whether these should be given greater weight in future.
Acres, for example, saw some promising results from its programme to herd monkeys away from homes, but cut short its experiment due to lack of funds.
Between September and December last year, it worked with the Upper Bukit Timah condominium Summerhill's management and security guards to herd the primates away.
Advisory notices were distributed to residents on how to interpret monkey behaviour and prevent them from stealing food.
Acres executive director Louis Ng said he understands that no culling has been done at the condominium since the experiment started, but the monkeys are no longer causing trouble.
The group also found that fruit trees and improper garbage disposal were what attracted the monkeys to the premises.
The results, however, could have been compromised by the culling in other parts of the neighbourhood. More information is also needed on whether complaints were made to the AVA or other authorities.
Other tests could include correlating the installation of monkey-proofed bins to the change in the number of complaints in an area, in the absence of culling.
More data, please
THERE is also a need for more information on the monkey population, and on why the number of complaints has repeatedly spiked and plunged in the past two decades.
There have been four major spikes: from 2000 to 2001, from 2006 to 2007, from 2008 to 2010 (data for 2009 was not available), and from 2012 to 2013.
These were almost all followed by steep falls in each of the following years. But the number of monkeys culled each year has remained relatively steady since 2007, with the only spike in 2013.
Nanyang Technological University Assistant Professor Michael Gumert, who studies monkeys, said this means the steep falls in the number of instances of public feedback could be due to something other than culling, since extensive culling was carried out only in 2013.
He added that the pattern of sharp spikes calls for more investigation into the causes.
He said: "The steep rises could be due to a rise in property openings, for example. People tend to complain a lot when they move in, but they get used to the situation and stop complaining after a while."
More information on the true monkey population would help inform decisions on whether and when culling or other methods, such as sterilisation, may be needed to help manage the population, and to what extent.
Prof Gumert and Acres' Mr Ng believe that the rise in human-monkey conflicts has been partly due to the siting of residential areas closer to the nature reserves.
Sterilisation an alternative
LOOKING abroad for answers, sterilisation could be a more humane alternative to culling if the monkey population needs to be controlled.
Hong Kong has done this since 2007. That year, its government launched a large-scale contraceptive programme to control growth in the wild monkey population.
Initially, female monkeys were given a vaccine to stop them from becoming pregnant, but this was effective for only three to five years, which means the females had to be rounded up again and again. In 2009, the government switched to a permanent surgical method. All treated monkeys are injected with a microchip for easy identification.
Between 2007 and 2013, Hong Kong sterilised 2,790 monkeys, bringing the population down by about 15 per cent to 2,000.
To reduce the monkeys' dependence on humans, the government planted 200,000 fruit trees in parks between 2001 and 2008.
The number of monkey-related complaints from the public fell from a high of slightly more than 1,400 in 2006, before the sterilisations started, to 290 in 2011. It rose to 529 in 2013, but this was linked to more people feeding the monkeys illegally in parks.
The Hong Kong government has stressed that birth control is only part of the programme, and public education is necessary.
With fewer monkeys in Singapore now, the Government would find it easier to count the primates' population, and work out how to manage the population through sterilisation.
This method, however, is not without its critics. NTU's Prof Gumert said that sterilising monkeys could change the social hierarchy of the troops and lead to unexpected consequences. That would have to be studied closely.
Suggestions aside, the fact remains that some of the monkeys may need to be culled if they pose a safety risk and cannot be reformed.
The crux of the issue is that more research should be done to satisfy both the culling and anti-culling camps.
That might also help to put everyone, from the authorities to residents to animal welfare groups, on the same page.