Bonnet macaques losing their ground in south India

It’s tough times for south India's bonnet macaques — a monkey that we think is irritatingly common could be losing ground to the larger and more aggressive rhesus macaque of the north. 

Other factors contributing to their decline include rapid urbanisation (as roadside trees are felled and vegetation lost) and their disappearance from temples and tourist spots, says a study published in PLOS ONE. 

Bonnet macaques are endemic commensals: they are found only in peninsular India and live in close proximity with humans, adapting to habitats ranging from riverside temples to roadside fig trees.

 However, a study in 2011 suggested that rhesus macaques were invading the bonnet’s habitats in south India. 

Surveys To assess the current status of bonnet macaques, a team of scientists from institutes including Tamil Nadu’s Salim Ali Centre for Ornithology and Natural History (SACON) surveyed roadsides (1,140 km in total) in peninsular India which were considered the southernmost boundary for rhesus macaques and compiled distributional data from earlier studies in the area. 

They found that rhesus macaques have spread as far south as Karnataka’s Raichur district — adding 24,565 sq km to their former range — in an area where bonnet macaques used to reside. 

The team collated information on bonnet macaque presence from surveys between 1989 and 2015 along 651 km of Mysore's roadsides and found that over the last 25 years a staggering 65% of the population has disappeared. 

The scientists predict that many of these populations will go locally extinct in 10 years. High resolution satellite and Google Earth imagery between 2000 and 2006 and from 2015 on wards showed a decrease in tree cover on and around these roads; the loss of contiguous canopies now prevents the monkeys from colonising new areas. 

Vanishing numbers Bonnet macaques were present only in low numbers across 16 forest-dominated protected areas that the team surveyed in south India. 

They also found that bonnet macaques have disappeared from more than 48% of temples and tourist spots across Kerala, Karnataka and Tamil Nadu. 

These areas are no longer stable habitats for these monkeys, write the scientists. “People are now less tolerant to bonnet macaques,” says co-author H. N. Kumara, senior scientist at SACON. “Even in temples, they are captured and translocated elsewhere. 

If we can give them a little space, they will survive. We need to take more interest in these common and less-charismatic species before they decline like sparrows did.”