of unsuitable habitat. These were ill-considered moves as exotic introductions can cause havoc to island flora and fauna. Elephants also can be found in forested or mountainous areas of the islands; they were brought over from the mainland to help with timber extraction in 1883. About 270 species of birds are found in the Andaman and Nicobar Islands, 14 species of which are endemic. The islands' many caves are nesting grounds for the edible-nest swiftlet, whose nests are prized in China for bird's nest soup. The islands also serve as a stopover site for several migratory birds such as Horsfield's bronze cuckoo, Zappey's flycatcher and Javan pond heron. The territory is home for about 225 species of butterflies and moths. Ten species are endemic to these Islands. Mount Harriet National Park is one of the richest areas of butterfly and moth diversity on Andaman and Nicobar Islands. The islands are well known for prized shellfish, especially from the genera Turbo, Trochus, Murex and Nautilus. Earliest recorded commercial exploitation began during 1929. Many cottage industries produce a range of decorative shell items. Giant clams, green mussels and oysters support edible shellfishery. The shells of scallops, clams, and cockle are burnt in kilns to produce edible lime. There are 96 wildlife sanctuaries, nine national parks and one biosphere reserve in the Andaman and Nicobar Islands. Demographics Census of India, the population of the Union Territory of Andaman and Nicobar Islands was 379,944, of which 202,330 (53.25%) were male and 177,614 (46.75%) were female. The sex ratio was 878 females per 1,000 males. Only 10% of the population lived in Nicobar islands. 150 years ago, the original population of the islands – the Great Andamanese, the Onge, the Jarawa and the Sentinelese, were estimated to be around 5,000. The population of islands increased massively due to the policies of Govt of India into islands under Jawaharlal Nehru in the late 1960s, that brought settlers from other parts of the country. The areas and populations (at the 2001 and 2011 Censuses) of the three districts are: There remain approximately 400–450 indigenous Andamanese in the Andaman islands, the Jarawa and Sentinelese in particular maintaining steadfast independence and refusing most attempts at contact. In the Nicobar Islands, the indigenous people are the Nicobarese, or Nicobari, living throughout many of the islands, and the Shompen, restricted to the hinterland of Great Nicobar. More than 2,000 people belonging