Tammars used to live over a wide area of Southern Australia from south-western Western Australia to southern South Australia and western Victoria, but most mainland populations are now extinct due to land clearing and degradation and predation by foxes and cats. The stronghold of the tammar is Kangaroo Island, south of Adelaide, where it is so plentiful it is regarded as an agricultural pest. There are no foxes on this island, and land-clearing regulations have limited habitat destruction. About a quarter of Kangaroo Island is still covered by native vegetation, and many farms adjoin bushland or have tracts of scrub along the creek lines, making for ideal conditions for tammars. The tammars shelter in the scrub in the day time and at night move out to feed on the paddocks.
Tammars are also found on a number of islands the coast of southern Western Australian. The population on the Abrolhos Islands offshore from Geraldton, were reported by one of the earliest European explorers of this area, Francisco Pelseart, in 1629. There are also large numbers on Garden Island south of Perth, and islands in the Recherche Archipelago round the south coast. Some small mainland populations exist in Western Australia, and these are being managed by the Department of Conservation and Land Management (CALM) in WA. Extensive baiting programs to control fox populations have led to a resurgence of a number of these populations. Mainland populations in South Australia became extinct in the 1920’s, but wildlife authorities are working to re-establish some of these populations using tammars repatriated from Kawwu Island in New Zealand where there is a feral population originally established from South Australian mainland stock.
The mainland and various island populations have been geographically and genetically isolated since the sea-level rises after the last ice age about 10,000 years ago, and so the animals in these various populations are genetically distinctive.
This map shows the current distribution plus the past range based on fossil evidence.