Kerguelen is the closest land to the Heard and McDonald Islands, lying about 450 km to the north-northwest. Kerguelen is a French territory (Terres australes et antarctiques françaises, French Southern and Antarctic lands), and has a permanent scientific base with 50–100 personnel.
Like Heard, Kerguelen is of a volcanic origin (part of the eponymous Kerguelen Plateau), and has glaciers covering higher elevations. However, Kerguelen is much larger, and features many more U-shaped (glacial) valleys, as well as fjords. Temperatures at the French base of Port-aux-Français are generally a little warmer than at Atlas Cove on Heard Island, but are still generally cold, wet, and windy.
Unlike Heard Island, where no human-introduced species are known, Kerguelen has both native and non-native species in the wild. It is one of two places in the world (the other being South Georgia island) where penguins, elephant seals, and reindeer can be found together. Reindeer were introduced to Kerguelen and South Georgia during the days of whaling, as a source of local food for sailors. However, after fur seal and elephant seal stocks had been decimated and sealing and whaling activities in the region ceased, so too did the human predation on the reindeer. Now, with no predators to eat them, the reindeer have been out-competing some of the native animals. In South Georgia, a reindeer hunt has been undertaken to drastically reduce their numbers, while at Kerguelen, scientists are conducting studies of the number of reindeer and their impacts on the local ecosystem.
I am looking forward to visiting Heard Island and the Kerguelen Islands. It will be interesting to compare the two in person, to see what similarities and differences I can notice.