Rhesus Macaque of Guwahati city: Baseline Survey reveals that popular perception about the increase in its population is far from reality

The popular perception of rise in monkey population behind ‘monkey menace’ in different areas of Guwahati city provoked wildlife biologist Dr. Narayan Sharma to do a fact check. Unfortunately, he could not find any data.

This motivated Sharma, Assistant Professor of the Department of Environmental Biology and Widlife Sciences of Cotton University, to conduct a baseline survey on Rhesus Macaque (Macaca mulatta) in the capital city with the help of students of the Department. The preliminary results have revealed that there is a huge gap between ‘perception’ and ‘reality’ on Rhesus Macaque population, says Sharma, a primate specialist.

The baseline survey of Rhesus Macaque (Macaca mulatta) living in any urban areas, is the first of its kind in the entire north-east, he adds.

The baseline survey is still going on. However, it is completed in two major locations -Assam State Zoo cum Botanical Garden area ( including the Hengerabari Reserve Forest area) and Gauhati University area.

“The perception is that monkeys are huge in numbers. They come in hundreds, create a havoc and their numbers are increasing in many fold. In Zoo area for instance, residents of the locality used to tell our team members that there are over 700 monkeys. However, during our 15-day long field survey that was conducted between December 16 and 29, 2020 we could count only 383 individuals of Rhesus Macaque, which is an average population”, Sharma tells nezine.com.

The population break up of this 383 individual is— 67 adult males, 125 adult females, 102 sub-adults, 89 juveniles and infants.

He says that perception among the residents of Gauhati University area too, was similar. However, the team could count only 200 individuals in three groups. The final report of the area is, however, yet to be compiled, he says.

The city has many locations of Rhesus Macaque population including Maligaon, Kamakhya, Nabagrah temple, Beltola. The survey will cover all these locations.

“The field survey is not a difficult task. Although Rhesus Macaque do not fiercely demarcate group territory, they generally live in own territory. This has helped us to identify their home ranges,” Sharma says.

The study that started in September, 2020 has been conducted with proper scientific tools and methodology. The initial phase was mapping of their habitat. The individual count include male-female break up of a group, counting of adult, sub-adult, juvenile infant, group size and age sex composition .

Female count is considered more important as unlike the male, who tends to migrate, females remain in the same group. Students of the department also recorded other significant body marks including injury or cut marks (if any) on their body, for easy identification of them in future.

“One of the major component of the baseline survey is to study whether these primate share same kind of parasite with human and if yes, in which area the parasite load is more—urban, semi-urban or forest. It also looks at the possibilities of spill over of any diseases to human body”,Sharma adds.

The survey will also includes studying innovative behaviours of primates like gestural communication (begging for food from human), object manipulation (drinking cold drinks from bottle), using tools( breaking a wall-nut with a stone).

“Studying behavioural changes is an interesting component. Anatomy can be fossilised but not behaviours, and they will continue for centuries and develop over the time”, Sharma says.

“Rhesus macaques are a multi male-multi female society, and they live in groups with the mean group size of 35, though the group size could be up to 250 animals in some of the temples and tourists sites. The average age-sex ratio is about 2 adult females to one male, 1.7 immature per one adult female, 0.6 infants per one adult female or 1 immature per one adult. However, these ratios vary according to variation in the ecological conditions and interference in their social system. This will also have impact on reproductive behavior and survival rate of an individual. Females attain puberty at the age of 3, and start reproducing at the age of 3.8, where males attain puberty at the age of4 but attain full adulthood at the age of 8 years. Majority of mating occur between October and December, and births coincides with the end of rainy season (Lindburg1971). Gestation lasts for 164 days, and the inter birth interval vary between 12 and 24months. Rhesus macaque is omnivore and feeds on a wide variety of plant and animal (invertebrate) origin foods (reference). Home range sizes vary a lot depending on the occupied habitat and the resource availability i.e. 0.1 to 15 km2, however, the average home range size is about 5 km2 reference (Singh et al 2016)” states the final report titled “Rapid Population Estimation of the Rhesus Mecaque in Assam State Zoo Cum Botanical Garden”.

Sharma says that he was always interested in conducting a baseline survey of Rhesus Macaque but always stuck up with hectic academic schedule. However, during Covid-19 pandemic situation, the worldwide lockdown gave him the opportunity to plan for such an extensive survey using scientific tools and methodology, and to create a database of Rhesus Macaque population in the capital city.

Developing a Monkey App is also underway to collect data. Sharma says the field works of the survey will be completed around June and it may take another two or three months for further compilation of data.

A photographic and video documentation of the findings are also a part of the baseline survey.

“Rhesus macaque is one of the most commensal primates. In some of the cases both human and rhesus macaque are seem to co-exist but in most cases rising conflicts between the two can be seen. Our study may help to reduce the issue if not mitigate it,” the final report states. The survey team led by Dr. Narayan Sharma includes Anushka Saikia, Dhiraj Kumar Das, Pramod Choudhury, Prastuti Bhattacharyya, Puja Kalita and Titir Debnath.

Ratna Bharali Talukdar

Photographs in this feautre courtesy Dr Narayan Sharma and his team