Gull Island is a granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 island, with an area of 8.5 ha

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

, in south-eastern Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It is part of Tasmania

Tasmania

Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

’s Passage Island Group, lying in eastern Bass Strait

Bass Strait

Bass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...

 south of Cape Barren Island in the Furneaux Group. It is a conservation reserve. With Forsyth

Forsyth Island

Forsyth Island is a granite island, with an area of 167 ha, in south-eastern Australia. It is part of Tasmania’s Passage Island Group, lying in eastern Bass Strait south of Cape Barren Island in the Furneaux Group...

 and Passage Islands

Passage Island (Tasmania)

Passage Island is a granite and dolerite island, with an area of 253 ha, in south-eastern Australia. It is part of Tasmania’s Passage Island Group, lying in eastern Bass Strait south of Cape Barren Island in the Furneaux Group. It is a pastoral lease that has been used for grazing cattle...

 it forms part of the Forsyth, Passage and Gull Islands Important Bird Area

Important Bird Area

An Important Bird Area is an area recognized as being globally important habitat for the conservation of bird populations. Currently there are about 10,000 IBAs worldwide. The program was developed and sites are identified by BirdLife International...

 (IBA), identified as such by BirdLife International

BirdLife International

BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...

 because it supports over 1% of the world populations of Little Penguins and Black-faced Cormorant

Black-faced Cormorant

The Black-faced Cormorant , also known as the Black-faced Shag, is a medium-sized member of the cormorant family. Upperparts, including facial skin and bill, are black, with white underparts. It is endemic to coastal regions of southern Australia.-Ecology:The Black-faced-Cormorant feeds largely on...

s.

Fauna

Recorded breeding seabird

Seabird

Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

 and wader

Wader

Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...

 species include Little Penguin

Little Penguin

The Little Penguin is the smallest species of penguin. The penguin, which usually grows to an average of in height and in length , is found on the coastlines of southern Australia and New Zealand, with possible records from Chile.Apart from Little Penguins, they have several common names...

, Short-tailed Shearwater

Short-tailed Shearwater

The Short-tailed Shearwater or Slender-billed Shearwater , also called Yolla or Moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in Australian waters, and is one of the few Australian native birds in which the chicks are commercially harvested...

, White-faced Storm-Petrel

White-faced Storm-petrel

The White-faced Storm Petrel , also known as White-faced Petrel is a small seabird of the storm-petrel family. It is the only member of the monotypic genus Pelagodroma....

, Pacific Gull

Pacific Gull

The Pacific Gull is a very large gull, native to the coasts of Australia. It is moderately common between Carnarvon in the west, and Sydney in the east, although it has become scarce in some parts of the south-east, as a result of competition from the Kelp Gull, which has "self-introduced" since...

, Silver Gull

Silver Gull

The Silver Gull also known simply as "seagull" in Australia, is the most common gull seen in Australia. It has been found throughout the continent, but particularly coastal areas. The South African Hartlaub's Gull and the New Zealand Red-billed Gull The Silver Gull (Chroicocephalus...

, Sooty Oystercatcher

Sooty Oystercatcher

The Sooty Oystercatcher, Haematopus fuliginosus, is a species of oystercatcher. It is a wading bird native to Australia and commonly found on its coastline. It prefers rocky coastlines, but will occasionally live in estuaries....

 and Crested Tern.