Monkey business

Human-primate conflict and causes

Western purple-faced langur. Picture courtesy: Simon D. Blaettler

In a classic display of defense, Simon lifted his arms, exposing the excruciating wound, the pain of which he would have articulated had he known how to verbalize. “When I went close, he grabbed some leaves and gravel from the ground and made it as if to put it in his mouth,” said Kamani Weerasekera, resident of Makumbura Kottawa. Kamani guessed it right when she thought that he was hungry. When she gave him a banana, Simon grabbed it and gobbled it up without ceremony. An hour or so passed before officers from an already overwhelmed Wildlife office at Battaramulla came to the scene. Simon was coaxed into a cage. Yes, Simon is not his name. Monkeys don't have names. At best they have numbers that researchers use for reference purposes.

When Weekend Nation later called up the Wildlife office at Battaramulla to inquire after our anonymous monkey from Makumbura Kottawa, they claimed that it recovered and was set free. Let's admit it, the Wandura or monkey that frequent our rooftops are far less glamorous than the formidable elephant or crocodile. But the human primate conflict is very real. According to research over half of the world's primates are threatened due to human activities, resulting in habitat destruction due to deforestation, hunting for meat, or because they are considered agricultural pests.

Sri Lankan primates are endemic and considered either endangered or critically endangered. Of the five primate species found in Sri Lanka, the three monkey species, namely, the macaque (Macaca sinica), the grey langur (Semnopithecus priam), and the purple-faced langur (Semnopithecus vetulus) are party to the human-monkey conflict. Langurs or leaf monkeys are the most endangered because they are more susceptible to habitat change as they depend on undisturbed forests for survival. A frequent visitor to village gardens and rubber plantations, the Western purple-faced langur (Semnopithecus vetulus nestor) is one of 25 Critically Endangered primate species (IUCN 2008).

Being a predominantly Buddhist country, killing of primates for food is extremely rare now. However, the meat of the purple-faced langur was traditionally consumed for medicinal

purposes. But with the improvement of socio-economic standards, monkeys are rarely killed for consumption anymore.

They are considered pests like mice or roaches, to be shooed off with stones and crackers, slingshots and air guns. The most common cause of primate deaths was reported as predation by dogs (26%) according to Diurnal Primates in Sri Lanka and People's Perception (Nahallage et al). Among other causes of death were electrocution from contact with power lines (13%), hunting (8%) and roadkill (3%). “Air rifles are fatal,” emphasized Department of Wildlife Conservation, Director Wildlife Health, Dr. Tharaka Prasad. “Shoot them on the hard muscle and adults may survive, but shoot on soft tissue, such as the face or head, it is most certainly fatal. However, Tharaka ensured that air rifles are likely to be banned by law in the future.

Roof damage occurs when monkeys run across tiled roofs, in the absence of trees. Residents tend to remove large trees near houses to deny monkeys access to roofs, which aggravates the situation. Monkeys have now taken to powerlines, in the absence of trees.

At least five cases of electrocution are reported per week, informed Tharaka. Three out of these cases make a full recovery, every two are fatal. Then there are road kills, when monkeys attempt to cross roads on foot in the absence of trees or powerlines. Moreover, Tharaka explained that when the leadership of a troop changes the new leader kills the young ones. Juveniles that are either rejected or wounded in the process are also brought to the Wildlife office at Battaramulla.

“It’s very difficult to translocate monkeys,” explained Tharaka. When individuals are removed from a troop, they tend to become aggressive and bite people. So, we create a group and release them together. Tharaka admitted that the DWC is severely short-staffed. “We can’t attend to all the cases reported to us. Most often we are forced to ignore less serious cases.”

“Indeed, the Wildlife Department can’t handle this alone,” said Primatologist, Environmental Consultant and IUCN Commission of Education and Communication member Dr. Jinie Dela. She said that the issue requires the attention of a platform of representatives of the DWC, Forest Department, Central Environmental Authority, Urban Development Authority, National Science Foundation and experts on primates with field experience. “This is not a quick fix. It should consist of a call center that could centrally handle all reports and complaints.”

Dela opined that most complaints received by the DWC are made by ‘westernized’ urban dwellers. “They call up the DWC as soon as they hear a monkey running on the roof. The human-primate conflict is ten times more severe in the villages. But no one complains about it because villagers are comparatively more tolerant. What the DWC gets is just the tip of the iceberg.”

Dela explained that the problem has its roots in the 1970s government's decision to release Forest Department land to the people. With time and the increase in population and land prices larger home gardens were fragmented and distributed among family members. Often the first trees to get felled to make way for houses, as well as a source of timber, are the jack trees, one of the major food sources of monkeys.

“There are still undisturbed patches of forested land with deed issues. But once ownership is established, these too will be cleared and sold off,” warned Dela. She said that their lone fight for the canopy is a losing battle.

Western purple-faced leaf monkeys cause the biggest problems in the Colombo suburbs," explained Open University, Senior Zoology Professor, Dr. UKGK Padmalal. He explained that the populations of this species are isolated and fragmented in the suburbs although wild populations still exist in areas such as Indikada Mookalana, Waga. “Non-wild populations are restricted to scattered home gardens," said Padmalal. Encroachment and fragmentation of land for housing and infrastructure have all but annihilated the species.

“Their anatomy is designed for their leaf-eating habit. Habitat destruction is affecting their foraging and ranging patterns.” Pathmalal explained that anthropogenic activities are forcing them into isolated patches, giving them no choice but to roost in home gardens. “Translocation isn't practical and using deterrents such as firecrackers and slingshots are pointless when they have no place to go.”

According to Padmalal, purple-faced leaf monkey troops usually break into smaller groups when the number of individuals reaches 18 to 20, but limited space forces them to use one single home range. “This is why we must create vegetation corridors connecting home gardens and remaining forest patches. Plus these trees must be edible.”

According to Dela, kapok, areca nut, tamarind and breadfruit are trees preferred by monkeys.

The 2007 - 2013 range survey of the Western purple-faced langur by Dela and Padmalal, conducted in collaboration with the Forest Department, uncovered that conserving the Western purple-faced langur in home gardens may not be a viable option for the future. Most of the forests have to be restored, and some need to be enriched. “These small forest habitats should be linked to prevent their isolation and further degradation,” reiterated Dela. She further explained that since the linking had to be via modified areas such as village home gardens and rubber plantations, people's voluntary participation is imperative for the proper management of these forests.

Article originally published in The Nation