North Stack North Stack North Stack (Welsh: Ynys Arw, meaning "rugged island") is a small island situated just off Holy Island on the north-west coast of Anglesey. North Stack can also refer to the headland opposite the island. This is the site of a redundant fog warning station, comprising a number of buildings, including the Trinity House Magazine, built in 1861, where shells for the warning cannon were stored. These buildings now house a bird watching observatory, giving a view of South Stack lighthouse across Gogarth Bay, and the studio of artist Philippa Jacobs. The Precambrian quartzite cliffs of this headland, including
North West Island island is dominated by dense Pisonia forest. North West Island is an important nesting ground for seabirds and turtles. As many as 500,000 seabirds habitat the island at any one time. Seventy per cent of the total breeding population of wedge-tailed shearwaters on Australia's east coast nest on the island. The Capricorn silvereye, a small bird endemic to the southern Great Barrier Reef, is found on the island. The green sea turtle and the endangered loggerhead sea turtle nest on the island between November and February. Because of these important rookeries the size of nesting populations is monitored on an