Trefoil Island is an island with an area of 115.79 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 Trefoil Island Group, lying close to Cape Grim

Cape Grim

Cape Grim is the northwestern point of Tasmania, Australia.It is the location of the Cape Grim Baseline Air Pollution Station which is operated by the Australian Bureau of Meteorology in a joint programme with the CSIRO....

, Tasmania’s most north-westerly point, in 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:...

. It is owned by the Trefoil Island Aboriginal Cooperative and is home to an estimated 1.5 million breeding pairs of 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...

s, which are subject to annual muttonbirding

Muttonbirding

Muttonbirding is a seasonal harvesting activity, which may be recreational or commercial, of the chicks of petrels, especially shearwater species, for food, oil and feathers...

 activities.

Fauna

The island forms part of the Hunter Island Group Important Bird Area

Hunter Island Group Important Bird Area

The Hunter Island Group Important Bird Area comprises several islands in the Hunter and Trefoil Island Groups lying off the north-western coast of Tasmania, Australia...

. Apart from the Short-tailed Shearwaters, 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 shorebird 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...

, 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 Pied Oystercatcher

Pied Oystercatcher

The Pied Oystercatcher, Haematopus longirostris, is a species of oystercatcher. It is a wading bird native to Australia and commonly found on its coastline. The similar South Island Pied Oystercatcher The Pied Oystercatcher, Haematopus longirostris, is a species of oystercatcher. It is a wading...

. The Cape Barren Goose

Cape Barren Goose

The Cape Barren Goose is a large goose resident in southern Australia. The species is named for Cape Barren Island, where specimens were first sighted by European explorers.-Taxonomy:...

 also breeds on the island. Reptiles include Metallic Skink

Metallic Skink

The Metallic Cool-skink or Metallic Skink is a species of skink in the Scincidae family. It is endemic to Australia, found in southern Victoria, as well as in Tasmania where it is the most widespread and common lizard, occurring on many offshore islands in Bass Strait as well as the mainland. It...

 and the introduced Tiger Snake.