place in May that year, was announced. 180 tonnes of rat poison, brodifacoum, were dropped over 70% of the island, in what was the world's largest ever operation of this kind. Another 95 tonnes of rat poison was planned to be dropped by three helicopters in January 2015. In June 2015 the eradication programme concluded, apparently successfully, with the island believed "very likely" to be rat free. In 2017–18, an intensive six-month search by the South Georgia Heritage Trust, using sniffer dogs and baited traps, found no evidence of rodent presence. Monitoring will continue for a further two or three years. In 2018, the number of South Georgia pipits had clearly increased. Reindeer were introduced to South Georgia in 1911 by Norwegian whalers for meat and for sport hunting. In February 2011, the authorities announced that due to the reindeer's detrimental effect on native species and the threat of their spreading to presently pristine areas, a complete cull would take place, leading to the eradication of reindeer from the island. The eradication began in 2013 with 3,500 reindeer killed. Nearly all the rest were killed in early 2014, with the last (about 50) cleared in the 2014–15 southern summer. Marine ecosystem The seas around South Georgia have a high level of biodiversity. In a recent study (2009–2011), South Georgia has been discovered to contain one of the highest levels of biodiversity among all the ecosystems on Earth. In respect to species, marine inhabitants endemic to this ecosystem outnumber and (in respect to biodiversity) surpass well-known regions such as the Galápagos or Ecuador. The marine ecosystem is thought to be vulnerable because its low temperatures mean that it can repair itself only very slowly. On 23 February 2012, to protect marine biodiversity, the territory's government created the South Georgia and the South Sandwich Islands Marine Protected Areacomprising . Military After the Falklands War in 1982, a full-time British military presence was maintained at King Edward Point on South Georgia. This was scaled down during the 1990s until the last detachment left South Georgia in March 2001, after a new station had been built and occupied by the British Antarctic Survey. The main British military facility in the region is at RAF Mount Pleasant and the adjacent Mare Harbour naval base on East Falkland, and three Remote Radar Heads on the Falklands: RRH Mount Kent, RRH Byron Heights and RRH Mount Alice.