Back from the brink: Snail success stories

Members of the Australian Museum Malacology team – Dr Frank Köhler and Dr Isabel Hyman – and Taronga Zoo colleague, Parnee Bonson, visited Phillip Island as part of the AM-led Norfolk Island expedition. The team were on the look-out for Critically Endangered snails, and the results were astounding!

The Malacology team had undertaken several trips to Norfolk Island previously, but for the 2022 AM-led Norfolk Island expedition, the teams’ efforts were focused on new or previously poorly surveyed sites, particularly Phillip Island. The Norfolk Island Group has five land snail species listed as Critically Endangered. Two of these (Advena campbellii and Advena suteri) are found on Norfolk Island and are the subject of a current conservation project being led by the Australian Museum, in partnership with Taronga Zoo, Parks Australia, the Norfolk Island Regional Council and the Department of Infrastructure.

However, Phillip Island is the last known location of three Critically Endangered land snail species (Advena grayi, Advena phillipii and Advena stoddartii). Advena grayi was last collected alive in 1982 (which was about the worst point of deforestation for Phillip Island, caused by rabbits). Shells of all three species were reportedly collected in 1996, but the identities of the shells have never been verified and these species were feared extinct. The shells were held in the private collection of Owen and Beryl Evans, Norfolk Island locals and naturalists, but couldn’t be located. In 2020, our team specifically searched Norfolk Island for Advena grayi but only found a few old and worn shells and no evidence of any living populations.

In the most recent visit to Phillip Island, the AM team searched some sites that seemed promising (reasonably moist, and around the site of the only tree to survive the rabbits) but found nothing. Then they headed up towards Jacky Jacky Ridge, as this was the last known site for Advena grayi. Frank, Isabel, Parnee, James Tweed (PhD student from the University of Queensland) and Mark Scott (Norfolk Island local and citizen scientist) stopped there for lunch. While getting ready to leave, James started foraging for insects in the nearby flax plants – and found freshly dead snail shells! This prompted the whole team to start searching, leading to many fresh shells being found. Mark found the first live specimen, followed by several more – about 12 live specimens in total – in the flax plants throughout the patch.

The team will return at some stage for a more detailed search of the island to get a better idea of their distribution, but we are happy to confirm that the species found was Advena grayi, the species that was last collected alive in 1982! It was found alive and well, and in reasonably good numbers, which is extraordinary news. This means that Mark Scott was the first person in 40 years to find the rare snail Advena grayi. The achatinellid species Tornatellinops novoseelandicus was also found living on Phillip Island, where it had not been previously recorded.

About 400 collections of around 140 species were made during the visit to Norfolk Island Phillip Island. It is so exciting to confirm that three of the Critically Endangered species (Advena campbellii and Advena suteri on Norfolk Island and Advena grayi on Phillip Island) are still alive – and the hope is that in the future we can confirm that Advena phillipii and Advena stoddartii have survived.