Heard and McDonald Islands 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 kilometers in area and it has 101.9 km of coastline.
Evidence from microfossil records indicates that ferns and woody plants were present on Heard Island during the Tertiary (a period with a cool and moist climate.) Neither group of plants is present today, although potential Tertiary survivors include the vascular plant Pringlea antiscorbutica and six moss species.
Volcanic activity has altered the distribution and abundance of the vegetation.
The vascular flora covers a range of environments and, although only six species are currently widespread, glacial retreat and the consequent connection of previously separate ice-free areas is providing opportunities for further distribution of vegetation into adjacent areas.
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.
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.
Heard Island is dominated by Big Ben, and is largely covered by snow and glaciers.
McDonald Island is much smaller, covering only 100 hectares at the time of inscription, and is surrounded by several smaller rocks and islands.
The only active sub-Antarctic volcanos are found on these islands, with the volcano on McDonald Island erupting after inscription and doubling the size of the island.
The island group’s physical processes provide valuable indicators of the role of crustal plates in the formation of ocean basins and continents, of dynamic glacial changes in the coastal and submarine environment, and of atmospheric and oceanic warming.
The islands are distinctive among oceanic islands in being founded upon a major submarine plateau which in this case deflects Antarctic circumpolar waters northwards, with striking consequences for geomorphologic processes.
They also offer an active example of plume volcanism, providing direct geological evidence of the action of the longest operational plume system known in the world.
All World Heritage properties in Australia are ‘matters of national environmental significance’ protected and managed under national legislation, the Environment Protection and Biodiversity Conservation Act 1999.
This Act is the statutory instrument for implementing Australia’s obligations under a number of multilateral environmental agreements including the World Heritage Convention.
By law, any action that has, will have or is likely to have a significant impact on the World Heritage values of a World Heritage property must be referred to the responsible Minister for consideration.
Substantial penalties apply for taking such an action without approval.
The Heard Island and McDonald Islands group can be described as the wildest place on earth – a smoking volcano under a mantle of snow and glacial ice rising above the world’s stormiest waters.
On the horizon to the west, smaller volcanic fragments rise precipitously and defiantly out of huge Southern Ocean swells.
Verdant vegetation and multicolored bird colonies contrast in sharp relief against the dazzling white of snow and ice and the grey-black of volcanic rock.
The driving westerly winds above the Southern Ocean in these latitudes create unique weather patterns when they come up against the enormous bulk of Big Ben, including spectacular cloud formations around the summit and unbelievably rapid changes in winds, cloud cover and precipitation.