Lord Howe Island Land Snail Placostylus bivaricosus

Lord Howe Island Land Snail Placostylus bivaricosus

The Lord Howe land snail is a large terrestrial snail found only on Lord Howe Island. Its status has declined from common to endangered since rats were accidentally introduced to the island in 1918.

The genus Placostylus is a group of large ground dwelling gastropods with a disjunct distribution in the South west Pacific from the Solomon Islands, Fiji and New Caledonia, to Lord Howe Island and the northern extremity of New Zealand. The Lord Howe Placostylus has a brown, pointed shell up to 7cm long and 2 cm in diameter.

Historical accounts and fossil evidence indicate that the LHI Placostylus was formerly widespread and abundant on the island. The decline was first noted in the 1940’s and the species is now listed as critically endangered.

The Ship rat Rattus rattus is considered to be the major predator of the Lord Howe Island Land Snail, and likely to be a significant threat to its survival. European Blackbirds and Song Thrushes (self introduced around 1950) are also thought to be predators of Placostylus.

Habitat clearing and modification and habitat disturbance, possibly herbicides and pesticides also add to the species decline.

In 2001 a recovery plan was completed to protect and recover the LHI Placostylus in the wild. Actions include habitat and population surveys, community awareness raising and a captive breeding program.

The Foundation for National Parks & Wildlife agreed to fund the captive breeding and monitoring program.

The Lord Howe Island Board has already constructed a rodent and bird proof enclosure for the project. Over a period of two years, school children will closely monitor the captive snail population for any eggs laid and then measure growth rates and survival rates of the juvenile snails.

To teach children the value of invertebrates, their special charm and needs, the Foundation’s award winning teacher’s kit “Mitch The Mitchell’s Rainforest Snail” has been turned into a ‘Pete the Placostylus’ kit.

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