[5] Fauna on the island include the southern brown bandicoot, Caspian tern, ruddy turnstone, red fox, and European rabbit.

The pigs caused significant environmental damage, as they preyed on local fauna and their wallowing disturbed the salt marshes.

Looking in the direction of the sound ... a poor woman was discovered in a helpless state from hunger, exposure and thirst, lying down in a swampy place, among the mangroves, cold and wet.

From the exhausted state she was found in, she would probably not have survived another night, and she was saved by the will of Providence, for the place is quite unfrequented, being among lofty mangroves.Throughout the 1880s, several people suggested that Quail Island be used for "turning out partridges and other game," for military purposes, and, in 1909, as a labour site for unemployed men, though none of these proposals happened.

[5] Near the turn of the 20th century, then-chief inspector of fisheries and game Frederick Lewis asked the Land Department to turn the island into a preserve, calling it a refuge for wildlife and citing the variety of fauna on the island: "silver gulls, kangaroos, magpies, opossums, plover, bronze-winged pigeons, quail, wallabies and black swans."

The West Australian wrote in 1933 that the island had thus become the world's only native such settlement "where animals are permitted to thrive undisturbed in their natural sanctuary.

However, many koalas reportedly died in a 1936 fire, believed to be set by a farmer, and in later years contradictory accounts were released about the animals' well-being.