Haystack Island is an

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

located in

Investigator Strait Investigator Strait is a body of water in South Australia lying between the Yorke Peninsula, on the Australian mainland, and Kangaroo Island. It was named by Matthew Flinders after his ship, HMS ''Investigator'', on his voyage of 1801–1802. ...

off the south coast of

Yorke Peninsula The Yorke Peninsula is a peninsula located northwest and west of Adelaide in South Australia, between Spencer Gulf on the west and Gulf St Vincent on the east. The peninsula is separated from Kangaroo Island to the south by Investigator Strai ...

in the

Australian state The states and territories are federated administrative divisions in Australia, ruled by regional governments that constitute the second level of governance between the federal government and local governments. States are self-governing ...

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

about south-west of Stenhouse Bay. Since 1972, it has been part of the

Althorpe Islands Conservation Park Althorpe Islands Conservation Park is a protected area in the Australian state of South Australia occupying the Althorpe Island, Haystack Island and Seal Island (Investigator Strait), Seal Island in Investigator Strait near the town of Stenhouse ...

Description

Haystack Island is about south-west of Stenhouse Bay. It is described as ‘a narrow wall of sheer cliffs, undermined, indented and marked by fresh scars and rockfalls’ and that ‘has been eroded to a series of tall lobes connected by thin necks of rock that narrow to an almost knife-edge ridge’. It is surrounded by a ‘fringing wave-cut reef’. The island is about long by a maximum width of about and with the tallest lobe having a height of . Its long axis is aligned in a north-west to south-east direction. Access is reported as best done in calm seas and that the summit ridge can be reached from the island’s east coast via a rubble cone of rubble, taking care when climbing the slope’s ‘loose and crumbling’ surface. A survey carried out in 1982 by the responsible government agency used a

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

to access the island’s summit. A number of sources consider Haystack Island along with the Althorpe Islands and Seal Island to be a group of islands known as the Althorpe Islands Group.

Formation, geology and oceanography

Haystack Island was formed about 7350 years ago after sea levels rose at the start of the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

thereby separating

from

Kangaroo Island Kangaroo Island, also known as Karta Pintingga (literally 'Island of the Dead' in the language of the Kaurna people), is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, southwest ...

. Haystack Island consists of a seam of Bridgewater Formation

calcarenite Calcarenite is a type of limestone that is composed predominantly, more than 50 percent, of detrital (transported) sand-size (0.0625 to 2 mm in diameter), carbonate grains. The grains consist of sand-size grains of either corals, shells, ooi ...

that sits on a largely submerged ridge of Gleesons Landing

Granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

. Haystack Island rises from a depth of within from its southern shore.

Flora and fauna

Flora

A survey carried out in November 1982 found 11 species of plants making up a

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It m ...

covering the island’s ridge including Grey Samphire,

Marsh saltbush ''Atriplex paludosa'', commonly known as marsh saltbush, is a species of saltbush endemic to Australia. Description It grows as an erect shrub up to a metre high. Leaves are oval in shape, one to four centimetres long, and 2 to 15 millimetres wi ...

, and Nitre-bush in the deeper soils, and Cushion-bush, Round-leaved Pigface and

Southern Sea-heath ''Frankenia pauciflora'', the common sea-heath or southern sea-heath, is an evergreen shrub native to southern Australia. It is part of the Frankenia genus of the Frankeniaceae family. It can be prostrate or may grow up to 0.5 m in height. Pi ...

in the shallower soils.

Fauna

A survey carried out in November 1982 reported evidence of the presence of the following

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

animals - the

White-faced storm petrel The white-faced storm petrel (''Pelagodroma marina''), also known as white-faced petrel is a small seabird of the austral storm petrel family Oceanitidae. It is the only member of the monotypic genus ''Pelagodroma''. Description The white-faced ...

by the presence of ‘shallow burrows’ used during the ‘summer breeding season’,

Pacific gull The Pacific gull (''Larus pacificus'') 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 re ...

by the existence of a ‘large

midden A midden (also kitchen midden or shell heap) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecofact ...

of shell fragments was found on the highest dome, indicating a feeding site…’, and the

White-bellied sea eagle The white-bellied sea eagle (''Haliaeetus leucogaster''), also known as the white-breasted sea eagle, is a large diurnal bird of prey in the family Accipitridae. Originally described by Johann Friedrich Gmelin in 1788, it is closely related t ...

by the presence of a ‘maintained nest’.

Protected areas status

Since 1972, Haystack Island has been part of the Althorpe Islands Conservation Park. Since 2007, it has been a prohibited area where access is only allowed by permit in order to protect the breeding population of seabirds. Since 2012, the waters surrounding its shores are part of a habitat protection zone located within the boundaries of the Southern Spencer Gulf Marine Park.

References

{{DEFAULTSORT:Haystack Island Islands of South Australia Uninhabited islands of Australia Yorke Peninsula Investigator Strait