The Heard Island and McDonald Islands (abbreviated as HIMI) are an Australian external territory and volcanic group of barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size is 372 square kilometres (144 sq mi) in area and it has 101.9 km (63 mi) of coastline. Discovered in the mid-19th century, they have been territories of Australia since 1947 and contain the only two active volcanoes in Australian territory, the summit of one of which, Mawson Peak, is higher than any mountain on the Australian mainland. They lie on the Kerguelen Plateau in the Indian Ocean. The islands are among the most remote places on Earth: They are located approximately 4,099 km (2,547 mi) southwest of Perth, Western Australia, 3,845 km (2,389 mi) southwest of Cape Leeuwin, Australia, 4,200 km (2,600 mi) southeast of South Africa, 3,830 km (2,380 mi) southeast of Madagascar, 1,630 km (1,010 mi) north of Antarctica, and 450 km (280 mi) southeast of Kerguelen. The islands are currently uninhabited.
Heard Island, by far the largest of the group, is a 368-square-kilometre (142 sq mi) bleak and mountainous island. Its mountains are covered in glaciers (the island is 80% covered with ice) and dominated by Mawson Peak, a 2,745-metre (9,006 ft) high complex volcano which forms part of the Big Ben massif. A July 2000 satellite image from the University of Hawaii's Institute of Geophysics and Planetology (HIGP) Thermal Alert Team, University of Hawai'i showed an active 2-kilometre (1.2 mi) long (and 50–90 metres/164–295 feet wide) lava flow trending south-west from the summit of Big Ben.
Flowering Plants And Ferns:
Low-growing herbaceous flowering plants and bryophytes are the major vegetation components. The vascular flora comprises the smallest number of species of any major subantarctic island group, reflecting its isolation, small ice-free area and severe climate. Twelve vascular species are known from Heard Island, of which five have also been recorded on McDonald Island. None of the vascular species is endemic, although Pringlea antiscorbutica, Colobanthus kerguelensis, and Poa kerguelensis occur only on subantarctic islands in the southern Indian Ocean.
The main indigenous animals are insects along with large populations of ocean-going seabirds, seals and penguins.
Sealing at Heard Island came to an end in the late 19th century, after the seal populations there had either become locally extinct or reduced to levels too low to exploit economically. Since then the populations have generally 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 co-habitants 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.
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 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.