Beneath the watchful eyes of the Buddha and between the feet of pilgrims, the residents of Swayambhu go about their daily lives. The rhesus monkeys share the temple with monks from the many monasteries and the more jaded stray dogs soaking up the sun across the complex. With the surrounding forest protected by religious beliefs, the rhesus macaque population is thriving here, giving Swayambhu its name: ‘Monkey Temple’. Life may seem idyllic for these playful primates, but the increased contact with humans has already begun to have a hazardous effect on the health of the temple’s monkeys.

Besides Swayambhu, the rhesus monkeys can be found roaming other areas, such as Pashupati, Tripureshwor and Sankhu, reigning over both the urban and rural areas of Nepal. Dr Mukesh Kumar Chalise, an associate professor of zoology at Tribhuvan University, has been studying the monkeys of Kathmandu for over two decades, and is particularly familiar with the troupes in Pashupati and Swayambhu. He has counted roughly 50 monkeys in Pashupati and 450 in Swayambhu, where he has seen groups as large as 80 individuals banding together. He explains that the number of troupes per area is fluid due to the “fusion and fission” of groups, but that there are usually between seven and nine troupes in each area at a time. The number of individuals, however, has remained remarkably constant. 

“I have been counting since 1991, and it is always 425 to 450 monkeys,” says Dr Chalise, speaking of the Swayambhu area, and he puts it down to the extra food provided by the humans visiting the Stupa. But while these pilgrims see their actions as charitable, Dr Chalise warns that giving food to the monkeys does more harm than good, calling it “unhealthy and unnatural”. The 450 monkeys residing in Swayambhu occupy a space of approximately two and a half hectares, an area that, under normal conditions, would only provide sustenance for 40-50 individuals.

While the population is booming, Dr Chalise laments that the quality of life for the urban rhesus monkeys has suffered greatly when compared to their rural counterparts. The large population creates a great deal of competition among the monkeys, and the abundance and nature of the food has led to highly unusual breeding habits. “Sometimes they [the mothers] even have twins and triplets. Once, I recorded quadruplets, but they could not survive for more than a month because the mother didn’t have sufficient milk.” Dr Chalise also notes that in the forests, mothers only start breeding at about four or five years of age and leave at least two years between pregnancies, but at Pashupati and Swayambhu, females start giving birth at two years of age and continue to do so roughly every six months.

Early and frequent pregnancies lead to health complications for both mother and child, and are, according to Dr Chalise, directly related to the high percentage of human food in their diets. In the same way that genetically modified food and malnutrition can lead to excessive oestrogen production in humans, causing infertility and breast tissue diseases, these foods cause hormonal imbalances in rhesus monkeys as well.

The term used to describe human food donations is ‘wildlife provisioning’, defined as the “offering of food to an animal beyond its natural supply and the quality of the animal’s environment”. Recent studies have found the effects of provisioning, which occurs all over the world, to be far-reaching and severe. Processed human foods are high in fat and sugar, and primates gain weight and are at increased risk of cardiovascular diseases due to the high cholesterol levels.

While studying urban monkeys, Dr Chalise has found parasites in the monkeys’ faecal matter, as well as the presence of human illnesses such as flu, tuberculosis, whooping cough, and skin diseases within the population. His findings support the theory that provisioning increases disease transmission between monkeys and humans. “If people knew we have a common ancestor and a common disease root, then maybe they would be wise enough to stay away from the monkeys when they’re sick,” he says. As a result, the monkeys in urban areas live no longer than ten to twelve years, when they should be living up to twenty. Diseases can also be transferred from monkeys to humans, such as the herpes B virus. Lack of fruits and seeds in the diet also prevents the monkeys from fulfilling their natural role as seed dispersers through their droppings.

A far more noticeable effect of provisioning on the rhesus monkeys is the greedy, opportunistic and even risky behaviour demonstrated by the monkeys. “They are very quarrelsome—frequently fighting over food—and have learned to snatch and rob from humans,” notes Dr Chalise. Such aggressive behaviour is non-existent among the rhesus monkeys in rural areas, who avoid humans and accept no food from them. He adds, “The monkeys like to tease the dogs; in the forest, monkeys run away from carnivores, but in the temples, I’ve seen monkeys pulling the dogs’ tails.” Increased aggression has a negative impact on the monkeys’ interpersonal relationships, lowering the value of socialisation and group cohesiveness.

Primatologists across the globe, including Dr Chalise, are increasingly calling for humans to restrain from feeding their local monkeys. Living with animals is an integral part of Nepali culture, and the presence of monkeys in the temples offers pilgrims a sense of harmony with nature. However, visitors to the temples, according to Dr Chalise, should consider that the most charitable act towards the monkeys—and the ecosystem itself—may be to deny them human food. The monkeys are not just ornamental to the temples; their good health is crucial to the natural biodiversity of Kathmandu. 

- Worsley is a South African journalist currently working in Kathmandu. She is pursuing a science degree at the University of Cape Town