Mitchell's Rainforest Snail Thersites mitchellae Recovery Plan

NSW National Parks and Wildlife Service, July 2001
ISBN 0 731 6298 5

7.0 Management issues

7.1 Threats and reasons for decline

The major cause of the decline of Mitchell's Rainforest Snail is habitat destruction (Stanisic 1998; Stanisic 2000). Land clearing for agriculture and urban development across the species' range has been extensive, and many of the small areas of surviving habitat remain at risk of clearing and development. The habitat value of small remnants is typically judged from a large vertebrate-focussed perspective, and the conservation value of these sites for invertebrate species is often not appreciated (Ponder 1997).

The majority of known remaining populations occurs in small areas of remnant rainforest including narrow strips of rainforest bordering coastal wetlands. These small remnant areas, with a high perimeter to area ratio, are at risk from edge effects, including desiccation, habitat disturbance, frequent fire and invasion by exotic weeds and feral animals. There is little data available on the impact of these factors on land snails (Ponder 1997), but they are likely to be adverse.

Predation by birds and introduced mammals has been identified as a possible threat to Mitchell's Rainforest Snail (NSW Scientific Committee 1997; Australian Museum 2001). Mitchell's Rainforest Snail is preyed upon by the Noisy Pitta Pitta versicolor in Stotts Island Nature Reserve (Stanisic 2000). Introduced rats feed on land snails (Sherley et al. 1998; Ponder and Chapman 1999), and may prey on Mitchell's Rainforest Snail.

7.2 Social and economic consequences

This recovery plan recommends consideration of potential impacts on Mitchell's Rainforest Snail by consent and determining authorities considering proposed developments and activities in areas of known or potential habitat of the species. Implementation of protection and management measures identified in this recovery plan would include local community involvement, and may have a positive flow-on with economic benefits to the community.

Funding for implementation of actions would need to be allocated. Estimated costing for the implementation of recovery actions over the five years of the plan is provided in Table 2. Implementation has been costed at $56 000 (priority 1), $72 500 (priorities 1 and 2) and $79 500 (priorities 1, 2 and 3).

7.3 Biodiversity benefits

On a global scale, the number of threatened terrestrial and freshwater mollusc species is greater than any other taxonomic group, exceeding by far, for example, the combined bird and mammal species listed (Ponder 1997). Despite this, mollusc conservation, and indeed invertebrate conservation in general, has not had a high profile. The profile of threatened invertebrate species, and of invertebrate conservation in general, will be raised in the community through awareness of the status of Mitchell's Rainforest Snail. This in turn will lead to greater opportunities for the conservation of threatened species and increased protection of biodiversity.

Actions to recover Mitchell's Rainforest Snail will assist in the conservation of other species that share its lowland rainforest habitat.

Land snails in eastern Australia are good indicators of climatic refugia for rainforest (Stanisic 1994), and hence species like Mitchell's Rainforest Snail are potentially of significant value in assisting reserve design to ensure longer-term biodiversity conservation.

8.0 Previous actions undertaken

8.1 Listing under TSC Act

Mitchell's Rainforest Snail was listed as endangered under the TSC Act in March 1997 (NSW Scientific Committee 1997), and was one of the first invertebrate species to be listed. Lowland rainforest on floodplain in the NSW North Coast bioregion, including the habitat of Mitchell's Rainforest Snail, was listed as an endangered ecological community under the TSC Act in August 1999 (NSW Scientific Committee 1999).

8.2 Survey and research

Targeted surveys for Mitchell's Rainforest Snail in 1998 and 1999 (Stanisic 1998; Stanisic 1999) were funded by the NSW National Parks and Wildlife Service (NPWS). These surveys recorded Mitchell's Rainforest Snail at four sites, three of which were new localities for the species, and provided valuable information concerning the species' habitat requirements.

A survey for the species on Stotts Island in 1999 (Stanisic 2000) was jointly funded by the NPWS and Queensland Museum. This study provided information on the distribution and status of the species on Stotts Island, identified potential threats to the population and provided recommendations for management.

8.3 Habitat identification and protection

Byron and Tweed Shire Councils have recently completed shire-wide vegetation mapping projects, including mapping of lowland subtropical rainforest and swamp sclerophyll forest remnants. This information will assist with implementation of recovery action 8 listed in this plan.

The significant area of known habitat for Mitchell's Rainforest Snail at Stotts Island is protected in Stotts Island Nature Reserve. Some additional areas of known habitat and potential habitat are afforded a level of protection through being within or in proximity to wetland areas identified under State Environmental Planning Policy (SEPP) No. 14 (Coastal Wetlands) and/or within environmental protection zones under the relevant Local Environmental Plans. SEPP No. 14 Coastal Wetlands of relevance or potential relevance comprise those between the Tweed and Richmond Rivers in northern NSW. Specific SEPP No. 14 Coastal Wetlands currently known to contain or be in close proximity to extant populations of Mitchell's Rainforest Snail are Wetland numbers 24 (Banora Point), 79, 80a and 81 (Byron Bay) and 87 (Lennox Head). It is anticipated that populations of Mitchell's Rainforest Snail or areas of potential habitat will be found within or near additional SEPP No. 14 Coastal Wetlands through habitat mapping, scientific surveys and community awareness as outlined in this recovery plan.

8.4 Community awareness

The NPWS has raised the public profile of Mitchell's Rainforest Snail during 2000/2001 through regional, state and national media including television, radio, newspaper and popular magazines.

The Foundation for National Parks and Wildlife included Mitchell's Rainforest Snail as one of six feature species in its 2000 Threatened Species Appeal.

The NPWS has prepared a community awareness brochure (Appendix 2) detailing where Mitchell's Rainforest Snail lives and how to identify it, the threats to its survival, and how the community can assist in its conservation and recovery. This brochure has been widely distributed in the Tweed/Byron/Ballina area through local NPWS offices, local Councils, and Landcare and other community organisations.

The NPWS and Tweed Shire Council have prepared new interpretive display material for the public visitation facilities at Bruce Chick Park, adjacent to Stotts Island Nature Reserve, in accordance with the plan of management for Stotts Island (NPWS 2001). The new display features information on Mitchell's Rainforest Snail and promotes community awareness of the significance of Stotts Island for the conservation of the species.

The Australian Museum provides information on Mitchell's Rainforest Snail and other threatened land snails to the general public on its invertebrate zoology internet web site (Australian Museum 2001).

9.0 Species' ability to recover

Given the current information base available, the ability of the species to recover is unknown. The apparent ability of the species to persist as breeding populations in small remnants (Stanisic 1998) suggests a positive conservation potential. However, the species' long-term recovery will also depend on conservation and recovery of its lowland subtropical rainforest and swamp forest habitat.