A search of two remote islands in the Kimberley has revealed previously unknown populations of threatened native species, including the northern quoll and a tree-rat.

An 18-day survey of Lacrosse Island and Buckle Head, as well as a mainland site adjacent to these islands, found a wide range of species.

Using traps and camera sites for the first time in the area, the Western Australian department of parks and wildlife and Balanggarra Rangers found a healthy population of northern quolls, a marsupial which has suffered badly from invasive species such as feral cats and cane toads.

The survey team also found the common rock rat on both islands and a water rat on Lacrosse Island. All three sites were populated by the giant slender blue-tongue skink, which is only found in the northern part of the Kimberley.

The giant slender blue-tongue skink is found only in the northern Kimberley. Photograph: David Pearson/DPaW Photograph: David Pearson/DPaW

The threatened golden-backed tree rat was discovered on Buckle Island. The species is only known to exist on nine other islands in the Kimberley.

A bandicoot was caught on camera but it is currently a mystery as to whether the animal is was a golden bandicoot, which is threatened, or the more common northern brown bandicoot.

Scientists also unearthed a selection of chewed Owenia nuts, which suggests they were eaten by the scaly-tailed possum, which is endemic to the area. The possums evaded the researchers’ traps but were later pictured on camera.

The wildlife survey was conducted as part of the WA government’s Kimberley science and conservation strategy.

Albert Jacob, WA’s environment minister, said: “The state government’s $81.5m Kimberley science and conservation strategy is a bold vision for the Kimberley’s long-term conservation and will provide unprecedented protection for the region’s unique plants and animals, as well as creating tourism opportunities, and jobs for Aboriginal communities.”