Australia’s only active volcanoes

27 September 2010 | Fact sheet

Heard Islands and McDonald Island

Background:

Heard Islands and McDonald Island Marine Reserve (HIMI) is a spectacular and unique area of the world with considerable conservation significance. Discovered only in the mid 19th century, due to the region's harsh climate and isolation, HIMI's has been hardly impacted by human activities. The islands and surrounding waters teem with wildlife and other natural wonders that make HIMI a special place. Both Heard Island and McDonald Island are volcanically active. With its spectacular landforms, close to pristine terrestrial and marine biological communities and species of high conservation significance, the HIMI Marine Reserve became a World Heritage Site in 1997. The Australian external territory of Heard Island and McDonald Islands (HIMI), and the HIMI Marine Reserve are managed by the Australian Antarctic Division (AAD) of the Australian Department of the Environment, Water, Heritage and the Arts. The AAD is responsible for delivering the Australian Government's Antarctic goals (including subantarctic goals relevant to HIMI) and administers Australia's Antarctic science program.

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Size and Location

Heard Island is about 4,100 kilometres south west of Perth in Western Australia. The McDonald Islands are about 43 km further west. 1000 kilometres north of the Antarctic continent and about 4,700 kilometres from South Africa to the north west. Heard island covers 368 square kilometres and is dominated by Big Ben, an active volcano of 2745 m elevation. McDonald Islands are about 36okm square

Flora and Fauna

Heard Island and the McDonald Islands lie south of the Antarctic Convergence, the marine zone where the colder waters of the Antarctic converge with, and sink under the slightly warmer (waters of the subantarctic. Lying south of the Antarctic Convergence and surrounded by Antarctic waters, approximately 70% of Heard Island is permanently covered in glaciers with isolated vegetated headlands emerging between glaciers.

The surrounding waters contain unique and important marine species, many of which are not visible from the water's surface but which play a no less significant part in the HIMI ecosystem.

Heard island has twelve major glaciers and several minor glaciers, the majority of which radiate from the summit region of Big Ben, with individual glaciers separated by well-developed buttresses and smaller glaciers which descend from the the summits of Mt Dixon, Mt Anzac and Mt Olsen on Laurens Peninsula. There are no glaciers on the low-lying McDonald Islands. Heard Island has a number of moist, low-level terrestrial, freshwater and shallow near-shore marine environments (wetlands) scattered around its coastal perimeter. These wetlands areas are of high conservation significance.

The terrestrial, freshwater and relatively shallow marine waters (<1000 metres) of the Heard Island and McDonald Islands (HIMI) Marine Reserve provide critical habitat for a range of plant and animal, including southern elephant seals The islands provide a rare terrestrial home in the Southern Ocean for plants to grow. Vegetation covers almost 20 square kilometres of Heard Island, mostly in coastal areas at low elevations. The diversity of plants is low.

Heard Island is also the largest subantarctic island with no known human-introduced plants, and there is little human activity on the island, so its terrestrial ecosystems are close to pristine. Heard Island and McDonald Islands (HIMI) supports high numbers of many species of flying birds, penguins, seals and invertebrates.There are currently only two animal species at Heard Island considered to be 'aliens' (non-natives) : a thrip Apterothrips apteris and a mite Tyrophagus putrescentiae. Heard Island has, however, been exposed in the past to introduced species which have not persisted, probably due to the harsh climate (for example silverfish, house flies, clothes moths, sheep, cockroaches and a rat).

Three species of seal breed on Heard Island, southern elephant seals (Mirounga leonina), Antarctic fur seal (Arctocephalus gazella) and subantarctic fur seals (Arctocephalus tropicalis). During the 19th century sealing period, seals at Heard Island were hunted commercially for their oil and fur. Sealing at Heard Island ended in the late 1800s, when populations had been hunted to near-extinction. Since then seal numbers at Heard Island have increased. In particular, the population of Antarctic fur seals is increasing rapidly.

Heard Island and the McDonald Islands are free from introduced predators and provide crucial breeding habitat in the middle of the vast Southern Ocean for a range of birds. The potential introduction of rodents is considered the single biggest risk to the seabirds on Heard Island.

Penguins form the majority of the total seabird biomass on Heard Island. Because of their large populations, king and macaroni penguins are the most important predators of marine resources. The penguins consume a variety of fish species but krill and squid are also taken. The flying birds that breed at Heard Island comprise:three species of albatross (wandering, black-browed and light-mantled sooty); seven species of petrel (southern giant, Cape, Antarctic, Wilson's storm, and common diving and South Georgian diving petrels and fulmar prions); kelp gulls, Antarctic terns and subantarctic skuas, the endemic Heard Island sheathbill and the Heard Island cormorant. Of the breeding species, three are listed Threatened Species under Australian Federal legislation. Four species also have an IUCN conservation status of Vulnerable: macaroni and rockhopper penguins, wandering albatross and southern giant petrels. A Recovery Plan has been completed for Albatrosses and Giant Petrels, which calls for ongoing population monitoring of the species found at HIMI. There is also an Action Plan for Australian Birds, and a draft Recovery Plan for 10 Species of Seabirds, each of which includes some of the HIMI species.

Threats

There is considerable evidence that the climate of Heard Island and McDonald Islands (HIMI) is changing and is likely to increase the probability of alien species establishing. Since the late 1940s, the total area covered by glaciers on Heard Island has reduced by approximately 11%. Four coastal lagoons have been formed as a result of the retreat of the Brown, Compton, Winston and Stephenson glaciers. Some of the lagoons are closed and allow for easy walking along the coast, but some of the lagoons are open to the sea, and present a challenge to pass. Glacial retreat is also providing extra ice-free ground for colonisation by plants and animals, and is linking previously discrete coastal ice-free areas. Consequently, Heard Island has one of the most rapidly changing physical settings in the subantarctic. The increase in available habitat for plant colonisation, in conjunction with the combining of previously discrete ice-free areas, has lead to dramatic changes in the vegetation of Heard Island in the last 20 years or so. Some plant species are spreading and the structure and composition of plant communities is being modified. It is considered likely that further changes will occur, and possibly at an accelerated rate. Changes in population numbers of seal and seabird species are also expected - this may affect the vegetation through changes to the nutrient regime and level of physical disturbance through trampling. Scientists are studying the terrestrial ecosystems at Heard Island in an attempt to understand how it is likely to change if the climate at HIMI continues to warm, as is currently predicted

 Why protect it ?

HIMI's special qualities are widely recognised through it's conservation status under Australian legislation and number national and international agreements. The terrestrial, freshwater and relatively shallow marine waters (<1000 metres) of the Heard Island and McDonald Islands (HIMI) Marine Reserve provide critical habitat for a range of plant and animal species. The spectacular landscape at Heard Island and McDonald Islands (HIMI) is quite unlike anywhere else in Australia and has few, if any, parallels elsewhere in the world. The special qualities of the marine area were recognised in the declaration of the HIMI Marine Reserve in 2002. The Reserve includes the islands, but 64,630 of the 65,000 square kilometres of the Reserve is marine, making the Reserve one of the largest marine protected areas in the world. The islands are biological hot spots characterised by very high numbers of breeding and non-breeding seabirds and marine mammals. Vast colonies of penguins and petrels co-occur with harems of elephant seals and fur seals that call Heard Island home.

HIMI also helps contribute to our better understanding of global scientific questions through research and monitoring carried out in a close to pristine natural laboratory.


Bengal Tiger being Released into the wild from a boat in the Sundarbans