Due to its isolation from mainland Australia and protection afforded under its statutory status, Barrow Island is one of the most important conservation reserves in Western Australia. Nearly 2,800 species have been recorded on Barrow Island, including at least 24 endemic animal species and subspecies found nowhere else on Earth (7).
Barrow Island is home to 13 species of mammal, including a variety of marsupials as well as native rats, mice and bats. With no introduced predators such as foxes or cats on the island, and a lack of competition from species such as rabbits and cattle, Barrow Island is a haven for some species threatened on mainland Australia (8). Some mammals such as the burrowing bettong or ‘boodie’ now only remain on a few isolated islands like Barrow Island, having been driven to extinction on the mainland (9).
Five resident species are protected under Western Australian and Commonwealth legislation, these are the Barrow Island golden bandicoot, the Barrow Island burrowing bettong or ‘boodie’, the black-flanked rock-wallaby and the Barrow Island euro (10). Over half the world’s cetacean species are known to occur in Australian waters, and of these the most commonly seen in the Barrow Island region is the humpback whale and Indo-Pacific humpback dolphin (11).
A total of 119 bird species have been recorded on Barrow Island, 47 of which are either resident or regular migrants (1). Common landbirds found on Barrow Island include the spinifexbird, an endemic subspecies of the white-winged fairy wren, the singing honeyeater, the white-breasted woodswallow and the welcome swallow.(1) (3) (5). There are also a number of raptors present on the island, including the brahminy kite, osprey and white-bellied sea-eagle (1) (2).
Barrow Island is designated as an Important Bird Area by BirdLife International as it offers important habitat for summer and winter migratory shorebirds (3). Barrow Island is known to support significant populations of pied oystercatcher, grey-tailed tattler, red-necked stint and fairy tern (3).
Reptiles and amphibians
43 species of terrestrial reptiles have been recorded on Barrow Island, including a variety of dragons, legless lizards, geckos, skinks, snakes and monitors. Perhaps the most notable is the perentie, the second largest lizard in the world and Barrow Island’s top predator (2) (12). In terms of marine reptiles, Barrow Island’s coastline provides important sea turtle rookeries, particularly for green turtles and flatback turtles which come ashore to nest over the Australian summer months between November to February (2) (5) (12). Sea snakes are also commonly seen in the shallows surrounding Barrow Island (11).
Although arid, Barrow Island also supports one species of amphibian, a desert burrowing frog called Main’s frog, a species able to maintain a state of torpor underground during the dry season (12).
Fish and invertebrates
There is a rich variety of marine and terrestrial invertebrate life on Barrow Island. Between 2004 and 2006 an intensive survey recorded a total of 2,200 terrestrial invertebrate species on the island, including many believed to be new to science (7) (13).
The waters surrounding Barrow Island are protected within marine conservation reserves. The Barrow Island Marine Park was designated in 2004, and is home to an estimated 9,000 species including a great diversity of corals, fish and other marine species (7).
A total of 378 native plant species have been recorded on Barrow Island, and much of the landscape is dominated by spinifex grassland (7).
As with all isolated ecosystems, one of the biggest threats to island biodiversity is the introduction of invasive species. This is one of the leading causes of species extinction on islands, as native species often lack the adaptations necessary to cope with the introduction of predators or competitors (14). Introduced black rats were discovered on Barrow Island in 1990, but have since been eradicated thanks to a successful baiting programme (15).