Heard Island and McDonald Islands

The Territory of Heard Island and McDonald Islands (HIMI; ISO 3166 region code: HMD, HM, 334;) is an Australian external territory comprising a volcanic group of mostly barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall land area is 372 km (144 sq mi) and it has 101.9 km (63 mi) of coastline. Discovered in the mid-19th century, the islands lie on the Kerguelen Plateau in the Indian Ocean and have been an Australian territory since 1947.
Heard Island and McDonald Islands contain Australia's only two active volcanoes. The summit of one, Mawson Peak, is higher than any mountain in all other Australian states, territories or claimed territories, except Dome Argus, Mount McClintock and Mount Menzies in the Australian Antarctic Territory. This Antarctic territory is a land claim unrecognised by most other countries, meaning that Mawson Peak is the highest mountain with undisputed Australian sovereignty.
The islands are among the most remote places on Earth: They are located about 4,100 kilometres (2,500 miles; 2,200 nautical miles) southwest of Perth, 3,850 km (2,390 mi; 2,080 nmi) southwest of Cape Leeuwin, Australia, 4,200 km (2,600 mi; 2,300 nmi) southeast of South Africa, 3,830 km (2,380 mi; 2,070 nmi) southeast of Madagascar, 1,630 km (1,010 mi; 880 nmi) north of Antarctica, and 450 km (280 mi; 240 nmi) southeast of the Kerguelen Islands (part of French Southern and Antarctic Lands).
The islands, which are uninhabited, can be reached only by sea, and typically require a two-week voyage from Australia to visit.
Neither island cluster had recorded visitors until the mid-1850s.
An American sailor, John Heard, on the ship Oriental, sighted Heard Island on 25 November 1853, en route from Boston to Melbourne. He reported the discovery one month later and had the island named after him. His wife Fidelia Heard provided the first written description and drawings of the island. William McDonald aboard the Samarang discovered the nearby McDonald Islands six weeks later, on 4 January 1854.
No landing took place on the islands until March 1855, when American sealers from the Corinthian, led by Erasmus Darwin Rogers, went ashore at a place called Oil Barrel Point. From 1855 to 1882 a number of other American sealers spent a year or more on the island, living in appalling conditions in dark smelly huts, also at Oil Barrel Point. At its peak the community consisted of 200 people. By 1877, sealers had wiped out most of the seal population and left the island. In all, the islands furnished more than 100,000 barrels of elephant seal oil during this period.
A number of wrecks have occurred in the vicinity of the islands. There is also an abandoned building left from John Heard's sealing station that is situated near Atlas Cove.
The islands were formally claimed by the United Kingdom in 1910 and transferred to Australia on 26 December 1947. The transfer was confirmed in letters exchanged on 19 December 1950. The archipelago became a World Heritage Site in 1997.
Australians continuously occupied a station in Atlas Cove from 1947 to 1955. The first of these ventures arrived in December 1947 and stayed until February 1949. Two members of the 1952 wintering party died in May while returning to their hut: radio operator James Hoseason was swept out to sea, while dog trainer Graham Forbes was rescued from the sea but died while attempting to return to the base.
The first recorded aircraft landing on McDonald Island was made by Australian scientists Grahame Budd and Hugh Thelander on 12 February 1971, using a helicopter.
There were at least five private expeditions to Heard Island between 1965 and 2000. Several amateur radio operators have visited Heard, often associated with scientific expeditions. The first activity there was in 1947 by Alan Campbell-Drury. Two amateur radio DXpeditions to the island took place in 1983 using the callsigns VK0HI (the Anaconda expedition) and VK0JS and VK0NL (the Cheynes II expedition), with a further operation in January 1997 (VK0IR). The DXpedition in March 2016 (VK0EK) was organised by Cordell Expeditions, and made over 75,000 radio contacts.
Mawson Peak, atop Big Ben (Heard Island), was first climbed on 25 January 1965 by five members of the Southern Indian Ocean Expedition to Heard Island (sometimes referred to as the Patanela expedition). The second ascent was made by five members of the Heard Island Expedition 1983 (sometimes referred to as the Anaconda expedition). A helicopter landing was made at the summit by an Australian National Antarctic Research Expeditions (ANARE) team on 21 December 1986. An Australian Army team was successful in making the third ascent in 2000.
In 1991, the islands were the location for the Heard Island feasibility test, an experiment in very long-distance transmission of low frequency sound through the ocean. The United States Navy-chartered motor vessels MV Cory Chouest and Amy Chouest transmitted signals which were detected as far away as both ocean coasts of the United States and Canada.
The United Kingdom formally established its claim to Heard Island in 1910, marked by the raising of the Union Flag and the erection of a beacon by Captain Evensen, master of the Mangoro. Effective government, administration and control of Heard Island and the McDonald Islands was transferred to the Australian government on 26 December 1947 at the commencement of the first ANARE to Heard Island, with a formal declaration that took place at Atlas Cove. The transfer was confirmed by an exchange of letters between the two governments on 19 December 1950.
The islands are a territory (Territory of Heard Island and McDonald Islands) of Australia administered from Hobart by the Australian Antarctic Division of the Australian Department of Climate Change, Energy, the Environment and Water. The administration of the territory is established in the Heard Island and McDonald Islands Act 1953, which places it under the jurisdiction of the Supreme Court of the Australian Capital Territory, with the non-criminal laws of the Australian Capital Territory and the criminal laws of Jervis Bay Territory applying to the Territory. The islands are contained within a 65,000-square-kilometre (25,000 sq mi; 19,000 sq nmi) marine reserve and are primarily visited for research, meaning that there is no permanent human habitation.
From 1947 until 1955 there were camps of visiting scientists on Heard Island (at Atlas Cove in the northwest, which was again occupied by American scientists in 1969 and expanded in 1971 by French scientists) and in 1971 on McDonald Island (at Williams Bay). Later expeditions used a temporary base at Spit Bay in the east, such as in 1988, 1992–1993, and 2004–2005.
With the end of sealing in 1877, the only exploited resource is fish; the Australian government allows limited fishing in the surrounding waters.
There are no active military installations or defence personnel on the islands. However, as part of "Operation Resolute." the Royal Australian Navy (RAN) and Australian Border Force deploy Cape and Armidale-class patrol boats to carry out civil maritime security operations in both Australian mainland and offshore territories including the Heard and McDonald Islands. In part to carry out this mission, as of 2023, the RAN's Armidale-class boats are in the process of being replaced by larger Arafura-class offshore patrol vessels.
Despite the lack of population, the islands have been assigned the country code HM in ISO 3166-1 (ISO 3166-2:HM), hence the Internet top-level domain .hm. The time zone of the islands is UTC+5.
In April 2025, as part of a sweeping campaign of tariffs against its trading partners, the United States specifically implemented a 10% tariff against the islands, despite the islands being uninhabited, earning the islands widespread media coverage. The United States alleged the islands exported more goods to the United States than they imported, an allegation that appeared to be calculated from incorrect trade data. An analysis of U.S. import data and shipping records by The Guardian indicated some shipments were incorrectly labeled as coming from the remote islands instead of their correct countries of origin. According to export data from the World Bank, the US imported US$1.4m (A$2.23m) of products from Heard Island and McDonald Islands in 2022, nearly all of which was "machinery and electrical" imports.
Heard Island, by far the largest of the group, is a 368-square-kilometre (142 sq mi) mountainous island covered by 41 glaciers; 80% of the island is covered with ice. The Big Ben massif dominates the island: It has a maximum elevation of 2,745 metres (9,006 ft) at Mawson Peak, the historically active volcanic summit of Big Ben, to which the average ascent from shore is steeper than that for any island of comparable size or larger; only seven smaller islands are steeper. A July 2000 satellite image from the University of Hawaii's Institute of Geophysics and Planetology (HIGP) Thermal Alert Team showed an active 2-kilometre-long (1.2 mi) and 50- to 90-metre-wide (164–295 ft) lava flow trending southwest from the summit of Big Ben.
The much smaller and rocky McDonald Islands are located 44 kilometres (27 mi; 24 nmi) to the west of Heard Island. They consist of McDonald Island (186 m or 610 ft high), Flat Island (55 m or 180 ft high) and Meyer Rock (170 m or 560 ft high). They total approximately 2.5 square kilometres (15⁄16 sq mi) in area, where McDonald Island is 1.13 square kilometres (7⁄16 sq mi). There is a small group of islets and rocks about 10 km (6 mi; 5+1⁄2 nmi) north of Heard Island, consisting of Shag Islet, Sail Rock, Morgan Island, Drury Rock, and Black Rock. They total about 1.1 square kilometres (7⁄16 sq mi) in area.
Mawson Peak and McDonald Island are the only two active volcanoes in Australian territory. Mawson Peak is also one of the highest Australian mountains (higher than Mount Kosciuszko). It is surpassed by Dome Argus, Mount McClintock and Mount Menzies in the Australian Antarctic Territory, a territorial claim unrecognised by most other countries, meaning that Mawson Peak is the highest mountain over which Australia has true sovereignty. Mawson Peak has erupted several times since 2013 and as recently as May 2023. An earlier eruption was filmed on 2 February 2016. The volcano on McDonald Island, after being dormant for 75,000 years, became active in 1992 and has erupted several times since, most recently in 2005.
Heard Island and the McDonald Islands have no ports or harbours; ships must anchor offshore. The coastline is 101.9 km (63.3 mi) in extent, and Australia claims a 12 nmi (14 mi; 22 km) territorial sea and 200 nmi (230 mi; 370 km) exclusive fishing zone aroud the islands.
Heard Island is a heavily glaciated, subantarctic volcanic island located in the Southern Ocean, roughly 4,000 km (2,500 mi; 2,200 nmi) southwest of Australia. Eighty percent of the island is covered in ice, with glaciers descending from 2,400 m (7,900 ft) to sea level. Due to the steep topography of Heard Island, most of its glaciers are relatively thin (averaging only about 55 m (180 ft) in depth). The presence of glaciers on Heard Island provides an excellent opportunity to measure the rate of glacial retreat as an indicator of climate change.
Available records show no apparent change in glacier mass balance between 1874 and 1929. Between 1949 and 1954, marked changes were observed to have occurred in the ice formations above 1,500 metres (5,000 ft) on the southwestern slopes of Big Ben, possibly as a result of volcanic activity. By 1963, major recession was obvious below 600 metres (2,000 ft) on almost all glaciers, and minor recession was evident as high as 1,500 metres (5,000 ft).
The coastal ice cliffs of Brown and Stephenson Glaciers, which in 1954 were over 15 metres (50 ft) high, had disappeared by 1963 when the glaciers terminated as much as 90 metres (100 yd) inland. Baudissin Glacier on the north coast, and Vahsel Glacier on the west coast have lost at least 30 and 60 metres (100 and 200 ft) of ice vertically, respectively. Winston Glacier, which retreated approximately one mile (1.6 km) between 1947 and 1963, appears to be a very sensitive indicator of glacier change on the island. The young moraines flanking Winston Lagoon show that Winston Glacier has lost at least 90 metres (300 ft) of ice vertically within a recent time period. Jacka Glacier on the east coast of Laurens Peninsula has also demonstrated marked recession since 1955.
Retreat of glacier fronts across Heard Island is evident when comparing aerial photographs taken in December 1947 with those taken on a return visit in early 1980. Retreat of Heard Island glaciers is most dramatic on the eastern section of the island, where the termini of former tidewater glaciers are now located inland. Glaciers on the northern and western coasts have narrowed significantly, while the area of glaciers and ice caps on Laurens Peninsula have shrunk by 30 to 65%.
Between 1947 and 1988, the total area of Heard Island's glaciers decreased by 11%, from 288 square kilometres (111 sq mi) (roughly 79% of the total area of Heard Island) to only 257 square kilometres (99 sq mi). A visit to the island in the spring of 2000 found that the Stephenson, Brown and Baudissin glaciers, among others, had retreated even further. The terminus of Brown Glacier has retreated approximately 1.1 kilometres (11⁄16 mi) since 1950. The total ice-covered area of Brown Glacier is estimated to have decreased by roughly 29% between 1947 and 2004. This degree of loss of glacier mass is consistent with the measured increase in temperature of 0.9 °C (1.6 °F) over that time span.
Possible causes of glacier recession on Heard Island include:
The Australian Antarctic Division conducted an expedition to Heard Island during the austral summer of 2003–2004. A small team of scientists spent two months on the island, conducting studies on avian and terrestrial biology and glaciology. Glaciologists conducted further research on the Brown Glacier in an effort to determine whether glacial retreat is rapid or punctuated. Using a portable echo sounder, the team took measurements of the volume of the glacier. Monitoring of climatic conditions continued, with an emphasis on the impact of Foehn winds on glacier mass balance. Based on the findings of that expedition, the rate of loss of glacier ice on Heard Island appears to be accelerating. Between 2000 and 2003, repeat GPS surface surveys revealed that the rate of loss of ice in both the ablation zone and the accumulation zone of Brown Glacier was more than double average rate measured from 1947 to 2003. The increase in the rate of ice loss suggests that the glaciers of Heard Island are reacting to ongoing climate change, rather than approaching dynamic equilibrium. The retreat of Heard Island's glaciers is expected to continue for the foreseeable future.
Heard Island has a number of small wetland sites scattered around its coastal perimeter, including areas of wetland vegetation, lagoons or lagoon complexes, rocky shores and sandy shores, including the Elephant Spit. Many of these wetland areas are separated by active glaciers. There are also several short glacier-fed streams and glacial pools. Some wetland areas have been recorded on McDonald Island but, due to substantial volcanic activity since the last landing was made in 1980, their present extent is unknown.
The HIMI wetland is listed on the Directory of Important Wetlands in Australia and, in a recent analysis of Australian Commonwealth-managed wetlands, was ranked highest for nomination under the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (Ramsar Convention) as an internationally important wetland.
Six wetland types have been identified from HIMI covering approximately 1,860 hectares (4,596 acres): coastal 'pool complex' (237 hectares (590 acres)); inland 'pool complex' (105 hectares (260 acres)); vegetated seeps mostly on recent glaciated areas (18 hectares (44 acres)); glacial lagoons (1103 ha); non-glacial lagoons (97 hectares (240 acres)); Elephant Spit (300 hectares (741 acres)) plus some coastal areas. On Heard Island, the majority of these types suites are found below 150 metres (492 ft) asl. The wetland vegetation occurs in the 'wet mixed herbfield' and 'coastal biotic vegetation' communities described above.
The wetlands provide important breeding and feeding habitat for a number of Antarctic and subantarctic wetland animals. These include the southern elephant seal and macaroni, gentoo, king and eastern rockhopper penguins, considered to be wetland species under the Ramsar Convention. Non-wetland vegetated parts of the islands also support penguin and other seabird colonies.
The islands have an Antarctic climate, or tundra climate (ET) under the Köppen climate classification, tempered by their maritime setting. The weather is marked by low seasonal and daily temperature ranges; persistent and generally low-lying cloud cover; frequent precipitation and strong winds. Snowfall occurs throughout the year. Monthly average temperatures at Atlas Cove (at the northwestern end of Heard Island) range from 0.0 to 4.2 °C (32.0 to 39.6 °F), with an average daily range of 3.7 to 5.2 °C (38.7 to 41.4 °F) in summer and −0.8 to 0.3 °C (30.6 to 32.5 °F) in winter. The winds are predominantly westerly and persistently strong. At Atlas Cove, monthly average wind speeds range between around 26 and 33.5 km/h (16.2 and 20.8 mph). Gusts in excess of 180 km/h (112 mph) have been recorded.
Annual precipitation at sea level on Heard Island is in the order of 1,300 to 1,900 mm (51.2 to 74.8 in); rain or snow falls on about three out of four days. According to the Australian Bureau of Meteorology, Heard Island receives an average of 96.8 snowy days annually at Atlas Cove.
Meteorological records at Heard Island are incomplete.
Most of the flora species are mosses and lichens, with just twelve vascular plant species. The main indigenous animals are insects, along with large populations of ocean-going seabirds, penguins and seals.
There is vegetation, mostly mosses and lichens, on almost 20 square kilometres (7.7 sq mi) of Heard Island's coastal, low-elevation areas. There is not much plant diversity and there are very few flowering plant species and no trees or ferns. There are twelve vascular species on Heard Island, of which five are also on McDonald Island. The limited flora is due to the severe climate and limited ice-free areas.
Vascular species:
Bryophytes, such as mosses and liverworts, can grow in places of the islands that other plants do not thrive in, such as on rock faces. Lichens grow in many places on Heard Island with exposed rocks. Seventy-one species of lichens have been recorded from Heard Island and they are common on exposed rock, dominating the vegetation in some areas. As with plants, a 1980 survey of McDonald Island found lower diversity there, with just eight lichen species and a number of non-lichenized fungi recorded.
Heard Island does not have human-introduced plants, but the island does have one non-native plant: Poa annua, a European grass. It may have come naturally from the Kerguelen Islands, where it is widely present. The Poa annua grass may have been spread to the island by winds and by animals such as seabirds and seals.
Sealing at Heard Island lasted from 1855 to 1910, during which time 67 sealing vessels are recorded visiting, nine of which were wrecked off the coast. Relics that survive from that time include try pots, casks, hut ruins, graves, and inscriptions. Sealing caused the seal populations on Heard Island to either become locally extinct or reduced to levels too low to exploit economically. Modern sealers visited from Cape Town, South Africa, in the 1920s. Since then the seal populations generally have increased and are protected. Seals breeding on Heard include the southern elephant seal, the Antarctic fur seal, and the subantarctic fur seal. Leopard seals visit regularly in winter to haul-out though they do not breed on the islands. Crabeater, Ross and Weddell seals are occasional visitors.
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 surrounding waters are important feeding areas for birds and some scavenging species also derive sustenance from their cohabitants on the islands. The islands have been identified by BirdLife International as an Important Bird Area because they support very large numbers of nesting seabirds.
Nineteen species of birds have been recorded as breeding on Heard Island and the McDonald Islands, although recent volcanic activity at the McDonald Islands in the last decade is likely to have reduced vegetated and un-vegetated nesting areas.
Penguins are by far the most abundant birds on the islands, with four breeding species present, comprising king, gentoo, macaroni, and eastern rockhopper penguins. The penguins mostly colonise the coastal tussock and grasslands of Heard Island, and have previously been recorded as occupying the flats and gullies on McDonald Island.
Other seabirds recorded as breeding at Heard Island include three species of albatross (wandering, black-browed, and light-mantled albatrosses), southern giant petrels, Cape petrels, four species of burrowing petrels (Antarctic and Fulmar prions, common and South Georgia diving petrels), Wilson's storm petrels, kelp gulls, subantarctic skuas, Antarctic terns, and the Heard shag. Although not a true seabird, the Heard Island subspecies of the black-faced sheathbill also breeds on the island. Both the shag and the sheathbill are endemic to Heard Island.
A further 28 seabird species are recorded as either non-breeding visitors or have been noted during 'at-sea surveys' of the islands. All recorded breeding species, other than the Heard Island sheathbill, are listed marine species under the Australian Environmental Protection and Biodiversity Act (1999, four are listed as threatened species and five are listed as migratory species. Under the EPBC Act a recovery plan has been made for albatrosses and giant petrels, which calls for ongoing population monitoring of the species found at HIMI, and at the time of preparing this plan a draft recovery plan has also been made for the Heard Island cormorant (or shag) and Antarctic tern.
The recorded populations of some seabird species found in the Reserve have shown marked change. The king penguin population is the best-studied seabird species on Heard Island and has shown a dramatic increase since first recorded in 1947–1948, with the population doubling every five years or so for more than 50 years.
A paper reviewing population data for the black-browed albatross between 1947 and 2000–2001 suggested that the breeding population had increased to about three times that present in the late 1940s, although a Convention for the Conservation of Antarctic Marine Living Resources CCAMLR) Working Group was cautious about the interpretation of the increasing trend given the disparate nature of the data, as discussed in the paper. The discovery of a large, previously unknown, colony of Heard shags in 2000–2001 at Cape Pillar raised the known breeding population from 200 pairs to over 1000 pairs. The breeding population of southern giant petrels decreased by more than 50% between the early 1950s and the late 1980s.
Heard Island supports a relatively low number of terrestrial invertebrate species compared to other Southern Ocean islands, in parallel with the low species richness in the flora–that is, the island's isolation and limited ice-free area. Endemism is also generally low and the invertebrate fauna is exceptionally pristine with few, if any, (successful) human-induced introductions of alien species. Two species, including the thrips Apterothrips apteris and the mite Tyrophagus putrescentiae are thought to be recent, possibly natural, introductions. An exotic species of earthworm, Dendrodrilus rubidus, was also collected in 1929 from a dump near Atlas Cove, and has recently been collected from a variety of habitats including wallows, streams and lakes on Heard Island.
The arthropods of Heard Island are comparatively well known, with 54 species of mite and tick, one spider, and eight springtails recorded. A study over the summer of 1987–1988 at Atlas Cove showed overall densities of up to 60,000 individual springtails per square metre (10.75 sq ft) in soil under stands of Pringlea antiscorbutica. Despite a few recent surveys, the non-arthropod invertebrate fauna of Heard Island remain poorly known.
Beetles and flies dominate Heard Island's known insect fauna, which comprises up to 21 species of ectoparasite (associated with birds and seals) and up to 13 free-living species. Approximately half of the free-living insects are habitat-specific, while the remainder are generalists found in a variety of habitats, being associated with either supralittoral or intertidal zones, Poa cookii and Pringlea antiscorbutica stands, bryophytes, lichen-covered rocks, exposed rock faces, or the underside of rocks. There is a pronounced seasonality to the insect fauna, with densities in winter months dropping to a small percentage (around 0.75%) of the summer maximum. Distinct differences in relative abundances of species between habitats has also been shown, including a negative relationship between altitude and body size for Heard Island weevils (genus Ectemnorhinus).
The fauna of the freshwater pools, lakes, streams and mires found in the coastal areas of Heard Island are broadly similar to those on other subantarctic islands of the southern Indian Ocean. Many species reported from Heard Island are found elsewhere. Some sampling of freshwater fauna has been undertaken during recent expeditions and records to date indicate that the freshwater fauna includes a species of Protista, a gastrotrich, two species of tardigrade, at least four species of nematode, 26 species of rotifer, six species of annelid, and 14 species of arthropod.
As with the other shore biota, the marine macro-invertebrate fauna of Heard Island is similar in composition and local distribution to other subantarctic islands, although relatively little is known about the Heard Island communities compared with the well-studied fauna of some other islands in the subantarctic region, such as Macquarie and Kerguelen.
Despite Heard Island's isolation, species richness is considered to be moderate, rather than depauperate, although the number of endemic species reported is low. The large macro-alga Durvillaea antarctica supports a diverse array of invertebrate taxa and may play an important role in transporting some of this fauna to Heard Island.
The rocky shores of Heard Island exhibit a clear demarcation between fauna of the lower kelp holdfast zone and the upper shore zone community, probably due to effects of desiccation, predation, and freezing in the higher areas. The limpet Nacella kerguelensis is abundant in the lower part of the shore, being found on rock surfaces and on kelp holdfasts. Other common but less abundant species in this habitat include the chiton Hemiarthrum setulosum and the starfish Anasterias mawsoni. The amphipod Hyale sp. and the isopod Cassidinopsis sp. are closely associated with the kelp. Above the kelp holdfast zone, the littornid Laevilitorina (Corneolitorina) heardensis and the bivalve mollusk Kidderia bicolor are found in well-sheltered situations, and another bivalve, Gaimardia trapesina trapesina, has been recorded from immediately above the holdfast zone. Oligochaetes are also abundant in areas supporting porous and spongy layers of algal mat.
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