‘Ten top threatened’

By Chris Thomson | posted on April 7, 2018

FROM a furry staple of Albany’s suburbs to a trap-door spider that inhabits a single gully in the Stirling Range, the state biodiversity department has compiled a list of 10 priority terrestrial animals threatened across the Great Southern Region.

“The region is a biodiversity hotspot within a hotspot,” Department of Biodiversity, Conservation and Attractions ecologist Sarah Comer tells The Weekender.

Even on the leafy fringes of the Great Southern’s only city, one critically endangered species is commonly seen and heard.

“For the Western ringtail possum, Albany is one of three main population areas,” Ms Comer says.

“They’re spread from Cheynes Beach, around Waychinicup, across to Denmark, but there’s a real concentration of animals around the urban Albany area.”

Ms Comer says the Western ringtail has done “fairly well” in Albany, “with really high densities on the mounts”, but that its proximity to humans masks a marked contraction in possum populations.

“Then you have species like the critically endangered Gilbert’s Potoroo that was hanging on at Two Peoples Bay and has been translocated to Bald Island. We’ve got a fenced enclosure over at Manypeaks, but they’re very restricted in range,” she says.

“The Western ground parrot, also critically endangered with less than 150 left in the wild, is interesting, because when I started work here in 1999 they were found at Two Peoples Bay, Cheynes Beach, Fitzgerald River National Park and Cape Arid National Park, but now the core population has contracted back to Cape Arid.

“So they’re in a fair bit of strife.”

The possum, potoroo and parrot are on a threatened terrestrial species list Ms Comer developed with DBCA colleagues exclusively for The Weekender.

“At Little Beach, at Two Peoples Bay, if you stand there and look across the bay, that’s pretty much the global distribution of the potoroo and endangered noisy scrub-bird,” she explains of the incredibly small distribution of some creatures on the list.

“Two Peoples Bay was actually earmarked as a satellite town of Albany. Then in 1961 a local school teacher rediscovered the scrub-bird, which had for 70-odd years been thought extinct.”

The scrub-bird illustrates just how quickly some species can be pushed to the brink.

“With them, the early collections occurred around Torbay; there were heaps of collections in the 1800s, so they would have been right through this landscape,” Ms Comer says.

“They don’t fly, so they need long, unburnt vegetation for cover but also for the leaf vertebrates they eat.

“So, when they were rediscovered, they were in these moist gullies on Mount Gardner that had managed to escape fire.”

The potoroo, thought to have been extinct for more than a century, was only rediscovered in 1994 after marsupial researcher Dr Elizabeth Sinclair “caught a weird quokka” at the Little Beach reserve that had been protected from development after the scrub-bird was rediscovered.

“There’s this concept of short-range endemism, these species that have unbelievably restricted distributions based on microclimate, specific habitat parameters and where they end up left in the environment, and a lot of the invertebrates fall in there,” Ms Comer explains.

“The ones on this list are the Toolbrunup pygmy trapdoor spider, Sarah’s peacock spider, and the Stirling Range rhytidid snail.

“The trapdoor spider is literally only known from one south-facing gully microhabitat in the Stirling Range.

“The snail is carnivorous, and we only know of it in two locations in humid, shaded gullies under rocks on the south side of the range, east of Chester Pass Road, despite lots of searching.”

All three invertebrates are critically endangered in Western Australia, slightly better off than the impossibly cute dibbler.

“The dibbler’s just a gorgeous 80 to 90 gram carnivorous marsupial, and they were rediscovered over near Cheynes Beach,” Ms Comer says.

“They’re no longer there, but there’s a really important population in the Fitzgerald River National Park and also on the islands off Jurien Bay.”

Then there’s the Australasian bittern, a bird that is widely distributed but whose habitat is on the decline.

“They’re found in the eastern states and New Zealand and New Caledonia, but are really threatened by the loss of habitat,” Ms Comer says.

“The South Coast’s got some good bittern habitat around Cheynes, Manypeaks and then over toward Esperance.”

Rounding out the list is the freshwater Western trout minnow that inhabits the Goodga, Angove and Kent rivers.

“They’re only little fish,” Ms Comer says of the endangered minnow.

“Almost 20 years ago they put in a fish ladder for it because there were issues with the minnow moving up and down a weir that was put in [the Goodga River].”

She says local ecologists focus on caring for “landscapes and patches” of bushland, rather than on each species in isolation.

“That approach helps us get more bang for our buck when prioritising management practices,” she says.

“There’s loads of opportunities to volunteer for our recovery programs, and we rely heavily on people to report sightings of threatened species.”

And that goes even for the much seen and heard ringtail possum, sightings of which, like all threatened species, can be reported at https://www.dpaw.wa.gov.au/plants-and-animals/threatened-species-and-communities/threatened-animals.

Ms Comer says the ‘Top 10’ list is not exhaustive, but a spread of some of the Great Southern’s remarkable threatened species.

“What’s fabulous about the South Coast is that we still have really quite viable populations of all of those species here,” she explains.

“We’re so lucky to have all this diversity, and these animals that are on the edge make the Great Southern a remarkable place to live.”

Photo: Ms Comer near a good patch of Western ringtail possum habitat at Albany’s Mount Clarence.