Here's an interesting article from the Telegraph (UK) about the monkey population in Delhi:
India's civil servants caught up in Delhi "monkey wars"
Indian civil servants have been caught up in "monkey wars" after larger primates deployed to scare marauding macaques away from government buildings started coming under attack from their quarry.
More than 90 per cent carry tuberculosis, they swarm central government offices, prowl the landings, and bite through essential internet cables Photo: GETTY
By Dean Nelson, New Delhi
4:12PM BST 08 Aug 2011
There have been a number of attacks in the last year by macaques on langurs in what appears to be a reversal in the jungle pecking order in Delhi.
The implications are serious for those living in the heart of the Indian capital where the macaque population has grown unchecked in recent years amid a widespread reverence towards an animal which reminds Hindus of their monkey God Hanuman.
Many in the capital feed them on Tuesdays and Saturdays, which are marked as "Hanuman days." However, a series of attacks on members of the public has led to calls for the "monkey menace" to be dealt with.
More than 90 per cent carry tuberculosis, they swarm central government offices, prowl the landings, and bite through essential internet cables. Many attack people carrying food and even residents relaxing on their verandahs. Delhi's former deputy mayor was killed when he was attacked by a macaque on his apartment balcony and fell to his death.
In schools, government buildings and embassies, including the British High Commissioner's residence, the "monkey menace" has been kept at bay by a handler with a langur on a long chain. The langur is allowed enough rope to prowl the walls and ledges of the compound, leaving its scent which scares away the macaques.
Dr N P S Chavhan, a Primatologist at the Wildlife Institute of India, said the langurs deter the monkeys as part of a double act with their handler, each making noises to intimidate. "It's quite possible, the monkeys have adapted to the intimidation and fear of langurs and hit back whenever possible," he said.
Anuradha Sawney, a member of the Animal Welfare Board of India and owner of a monkey sanctuary just outside New Delhi, said the macaque's increasing boldness was down to its growing numbers in Delhi and its capacity to adapt to changing circumstances.
"If there are a lot of macaques the group will be strong and they will not be afraid to fight," she said.
Diljan Ali, a langur handler, complained that the government hires monkey men to confront the macaques but refuses to compensate them when their animals are defeated. "(The macaques) are very smart. They know when they have the advantage.
They attack in numbers and when they do it's pre-planned," he said.