The secret life of a rainforest snail

Australia’s rarest - and one our largest - land snails lives stealthily in debris on the rainforest floor, but miniature radio transmitters have revealed some of the species’ secrets, like what it eats and where it goes during the day.

Southern Cross University researcher Dr Jonathan Parkyn spent four years crawling around in leaf litter to learn more about the Mitchell’s Rainforest Snail, which has a shell up to 5cm wide, for his thesis, ‘Studies on the ecology of the endangered camaenid land snail Thersites mitchellae (Cox, 1864)’.

The Mitchell’s Rainforest Snail (Thersites mitchellae) is endemic to north-eastern New South Wales but habitat loss has restricted its distribution to just a handful of coastal remnants. Dr Parkyn’s work provides new information important for its conservation and management.

The malacologist, who was awarded his PhD at Southern Cross University graduation ceremonies last month, said radio transmitters proved extremely helpful.

“With conventional searching, locating the snails can prove tricky but by putting a transmitter on them we can track and locate previously tagged ones that normally would be out of sight.

“The snails with transmitters were observed in complex habitat, but due to their natural camouflage many would probably have often been overlooked without the aid of this technique.

“As a result we were able to demonstrate how active they were at night and how far they travelled as the humidity increased.”

Dr Parkyn’s research was conducted within the snail’s historical distribution - between the Richmond River at Ballina and north to the Tweed River near the Queensland border - and explored the population abundance, site occupancy, movement and habitat use of this rare and elusive species.

“The results from our study demonstrate that this snailis capable of relatively long-range movements within suitable habitat under favourable climatic conditions. This suggests that snails may be capable of colonising new habitat patches if appropriate connectivity is available between habitats, and this has important implications for future attempts to restore habitat for this critically endangered land snail.”

As well as its large size, another eye-catching feature of this snail’s shell is the shape: strongly elevated, giving it a triangular profile, in either reddish chestnut or black with two prominent yellow bands.

Mitchell’s Rainforest Snail is listed as critically endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, and was the first species for which a critical habitat determination was made under the New South Wales Threatened Species Conservation Act 1995.

“Prior to my work there were no reliable population estimates for Mitchell’s Rainforest Snailand information regarding the species habitat and ecology was necessarily based on general inferences from similar species,” said Dr Parkyn.

“These results provide new locations and range extension for the species. Also, the models and techniques used offer considerable scope for application to land snail conservation and improved understanding of habitat use particularly for those species and communities suspected to be at risk of extinction.”

Dr Malcolm Clark from the School of Environment, Science and Engineering presented Jonathan to receive his Doctorate award from the Southern Cross University Chancellor The Hon Dr John Dowd AO QC.

“I was fortunate to receive research design and statistical analysis assistance from Dr Lyndon Brooks in SCU’s research methodology unit, but the endeavour also benefited from the interdisciplinary collaboration of statistician and ecologists, particularly Dr Alison Specht and Dr David Newell in the School of Environment, Science and Engineering,” Dr Parkyn said.

One of Australia’s foremost experts on land snails, Dr John Stanisic from the Queensland Museum, also provided advice to Jonathan.

Photo: Dr Jonathan Parkyn holding a Mitchell's rainforest snail with a tranmission device attached to its shell.