. Long and thin, it has a length of and an average width of less than . A remnant of a four-million-year-old volcano, the island is dominated by a rocky ridge reaching to about at its highest point, called The Pinnacles. Sail Rock, a stack, rises from the ocean to the south of Hen Island, and is a prominent navigational point for yachts. By the late 1800s, Hen Island was the only place in New Zealand with a surviving population of North Island saddleback. The once common species of forest bird found in the North Island, was nearly wiped out by the human introduction of mammalian predators, such as rats and stoats. In the 1960s translocations of saddleback from Hen Island to other island sanctuaries around New Zealand began. Wareware and Muriwhenua Two small rocky islands with a combined area of . Mauitaha This , rugged, scrub-covered rock lies to the south of Muriwhenua. It rises to . The New Zealand Department of Conservation and the Ngati Wai iwi have entered into partnership to set up a sanctuary for the Polynesian rat, or kiore, on the islands Mauitaha and Araara. A spokesman for Ngati Wai said the kiore heritage will be protected as the movement of the kiore through the Pacific paralleled the migration of the New Zealand Maori. A spokesman for the Department of Conservation said the Department's policy change from eradication would assist scientific research. Lady Alice Island Named after Lady Alice Fergusson (wife of Governor General Sir Charles Fergusson), it is the largest of the five Chickens and is of particular significance because of its flora and fauna. The island covers and is surrounded by rocky reefs. It was occupied by Māori until the 1820s, and was used as a base for fishermen in the 1890s. Cattle were introduced at about this time, but were removed in the 1920s. Whatupuke Formerly known as Whakahau this island is composed of a large eastern section and a peninsula to the southwest. The coast of the peninsula forms one of the chain's main land features, a wide bay (Starfish Bay). The island covers , and is steep, rising to . Coppermine Island Coppermine island formerly known as Mauipane covers an area of . It is composed of two sections joined by a short isthmus. As the name suggests, there are copper deposits on the island, but attempts at mining them