The Coral Sea Islands Territory comprises the many small islands spread over a huge sea area of approximately 780,000 sq km, extending east and south from the outer edge of the Great Barrier Reef, and include Heralds Beacon Island, Osprey Reef, the Willis Group, and fifteen other reef/island groups. In 1969, the Coral Sea Islands became a territory of the Commonwealth under the Coral Sea Islands Act. In 1987, the boundaries of the Territory were extended around Elizabeth and Middleton Reefs. Discovered in 1803, they were briefly exploited for guano in the 1870s and 1880s but were soon abandoned due to a lack of permanent water. During the 19th century many ships were wrecked in the area due to constantly shifting sand cays, and the reefs and islands have often been named after the ships which foundered there. They are still uninhabited today, apart from a large population of sea birds, and the occasional meteorologist on Willis Island. Unmanned weather stations, beacons, and a lighthouse are located on several other islands and reefs. Occasional tropical cyclones sweep over the islands from November to April, leaving the sand and coral based mass with little or no vegetation. The coral and sand islands are quite small with some grass and low vegetation cover. There is no fresh water. Two species of sea turtle nest in the area, and at least twenty-four bird species have been recorded. A Migratory Birds Ordinance is in force, and gives effect to the Australia-Japan and Australia-China agreements on endangered and migratory birds. In 1982, the Lihou Reef and Coringa-Herald Nature Reserve were declared by the Commonwealth Government to protect the wildlife in this part of the Territory. In 1987, Elizabeth and Middleton reefs were declared a marine national nature reserve. All wildlife in the Territory is now legally protected under Part III of the National Parks and Wildlife Regulations.