Most city residents would have encountered, at some point, a small, rodent-like creature darting across their way and disappearing into a nearby burrow.
Found mostly in open forests and cultivated fields in the past, the common grey mongoose is today found even in places with dense population, and the mammal seems happy to survive and thrive in adapted surroundings.
Children’s Park at Guindy, Raj Bhavan, IIT-Madras, Adyar Poonga, Theosophical Society in Adyar and the neighbourhoods of Anna Nagar and Shenoy Nagar are some of the places in the city where the mongoose is commonly found, say naturalists.
Common mongooses have been found to live near bushes, dry zones and agricultural lands, according to researchers.
As they are known to attack snakes, they are always considered friends of human beings, especially farmers. They are commonly found all over the country.
Elsewhere, these small mammals have been known to live in Sri Lanka, the Himalayas in the North (up to 2,100 metres elevation), Bengal in the West, and up to Iran and Arabia in the East, say researchers.
D. Vasantkumar of Environmental Monitoring and Action Initiating, a non-governmental organisation involved in nature conservation, says despite growing human population, the common mongoose is seen in several parts of Chennai.
Mr. Vasantkumar says he has seen them in Anna Nagar, Shenoy Nagar and Adyar. They are particularly found in areas dotted with independent houses that have gardens or open spaces.
The mongoose takes shelter in burrows and tunnels. They come out only in the late evenings. By nature, these mammals are bold, which is why they have easily adapted to the city landscape. 
Some of them have even begun to consume human food, Mr. Vasantkumar says. A mongoose family at his friend’s house in Shenoy Nagar is often seen eating leftovers from discarded cake boxes, he says.
The common grey mongoose seems to have easily adapted to changing landscapes, and is now commonly found in urban areas

Source: http://www.thehindu.com/todays-paper/tp-national/tp-tamilnadu/farmers-friend-finds-home-in-chennai/article6650055.ece