Approximately one third of the total land area of the Cayman Islands is designated as a Protected Area. The terrestrial Protected Areas include Animal Sanctuaries, National Trust properties and Environmental Zones. Some of the most ecologically sensitive areas of the islands, including the Mastic Reserve, Salina Reserve, Central Mangrove Wetland and Brac Parrot Reserve are managed by the National Trust for the Cayman Islands. The National Trust was established as a non-profit non-governmental organisation in 1987 with the purpose of preserving the natural and cultural heritage of the Cayman Islands for future generations. It is responsible for the management of sites of both ecological and historical interest.