Facilitating the protection and restoration of endangered species and ecological communities on BC’s South Coast

A “pulmonate” snail, this species have evolved their mantle cavity into a lung (instead of gills as still found in some snails).  Breathing is through a single opening on the right side of the body which either remains open or opens and closes. Shell diameter 2.8-3.5 cm, shell diameter is 1.4 to 1.7 times shell height.  One of the largest land snails in BC, the shell has 5 to 6 whorls (spirals) with lighter colored axial ribs (thin bands that cross each whorl). The uppermost whorls are often pale from wear. Shell colour ranges from gold to dark brown, lightening to amber around the aperture (shell opening). As the snail matures the shell can become bleached looking and begin to flake. This species lacks the ‘hairs’ found on the shell of other land snail species. The thick white aperture lip of adult snails is evident when viewing the snail from below; juveniles lack this thickened aperture lip.

Download Species Fact Sheet in PDF

Status

Global Status: 
G2G3
Provincial Status: 
S1
SARA Status: 
Endangered
BC List Status: 
Red (Candidates for- Extirpated, Endangered, or Threatened status)

Similar Species

The large size, thick white shell aperture, and often bleached flaking appearance distinguish Oregon Forestsnail from most other land snails. Inexperienced observers will most likely confuse the introduced European Grove Snail (also called Brown-lipped Snail) which has become widely distributed especially in urban and rural areas of BC. Highly variable in shell colour and pattern, Grove Snail shells range from solid shades of dark brown or amber/yellow to shells with dark bands on yellow or grey. The closely related Puget Oregonian is almost the same size and also possesses a defined tooth on its shell aperture; but is believed to be extirpated from its historic range in BC. Pacific Sideband, though larger and more colourful, can have bleached, flaking shells as the snail matures. Northwest Hesperian, another native land snail is smaller (shell diameter <1.6 cm) and covered with short hairs, noticeable when the shell is held up to light.

Ecology

Range

Elevation: <350 m In B.C. Oregon Forestsnail is restricted to the Fraser Valley Lowlands and southeast Vancouver Island of the Coast Region. Occurrences range from both sides of the Fraser River, including: Langley, Chilliwack (Ryder Creek watershed, Little Mountain, Cheam Lake), Mission (Hatzic Prairie) and Abbotsford (McKee Peak and lower Sumas Mountain as well as the City proper). It has also been found at Colony Farm Regional Park in Coquitlam, historically near White Rock in the west and near Hope in the east. The species is known from one location on southeast Vancouver Island (Crofton) from where there are both historical (1903) and recent (2003) records. Known occurrence on South Coast BC represented by the green dotted line and green stars

Habitat

On South Coast BC, Oregon Forestsnail is found in broadleaf forests or mixed forests. The species is strongly associated with stands that support Bigleaf Maple, Western Redcedar, Red Alder, Salmonberry, Stinging Nettle, and Sword Fern. It is found on steep terrain and tends to utilize edge or transitional areas (“ecotones”). It generally requires intact, well-connected forested landscapes with high structural diversity and understory complexity. Habitat must provide a stable, moist microclimate and aestivation and hibernation sites that are essential to support various components of their life cycle. Pattern of distribution and abundance is poorly known. Even less is known about preferences for egg deposition sites or juvenile dispersal habitats which may vary across the range. Land snails are relatively sedentary and thought to have poor dispersal capabilities. Oregon Forestsnail can tolerate some level of disturbance but lacks necessary mobility to easily seek new undisturbed habitats. The species has been shown to utilize variable patch sizes from as little as 4 m2 to as large as 70 m2.Home range size however does not necessarily equate to the size and complexity of habitats needed to support a given population or populations. A thick leaf litter layer (5-10 cm) or moss layer is important for providing essential, moist microclimates that protect snails during cold temperatures and drought. Ground cover such as woody debris and rock piles provide additional foraging sites, areas for courtship and mating, summer refugia and winter hibernacula.

Diet

Oregon Forestsnail have a strong preference for understory herbaceous vegetation, especially Stinging Nettle and Sword Fern communities found in association with Bigleaf Maple, Salmonberry and Red Alder.

Life Cycle

Mating takes place during periods of high humidity (80-100%). Adults generally dig and deposit eggs in shallow nest holes in soft soil and leaf litter; nest holes may be shared. Oregon Forestsnail takes ~2-3 years to reach maturity and may live up to 5 years.

Threats

Habitat loss and fragmentation due to urbanization, logging, and clearing.
Direct mortality, alteration of forage plant communities, and loss of essential habitat features due to recreational activities (e.g. ATV use, mountain biking, hiking).
High vulnerability to activities that impact microclimate conditions (e.g. moisture), decrease food supplies, and create barriers to dispersal (e.g. land clearing, extensive paved areas). Land snails have low tolerance to drying and exposure and poor disp
Possible competition from introduced species such as European Grove Snail and Brown Garden Snail.
Alteration of forage plant communities and microclimate conditions due to the introduced invasive and exotic plant species.

Conservation and Management

Apply conservation and management objectives as set-out in the “Recovery Strategy for the Oregon Forestsnail (Allogona townsendiana) in Canada. Integrate complementary objectives, recommendations and assessment methods found in “Draft Gastropod Best Management Practices Guidebook Oregon Forestsnail and Other Land Snails at Risk in the Coastal Lowlands” (found on the SCCP’ website). Where appropriate, measures as set out in the RISC Standards #40 “Inventory Methods for Terrestrial Arthropods” should be applied. Habitat suitability mapping as done for “Big Leaf Maple distribution for Puget Oregonian” found in the “Recovery Strategy for the Puget Oregonian Snail (Cryptomastix devia) in Canada” may also be a useful for Oregon Forestsnail. Oregon Forestsnail may occur under different habitat conditions than known, assessments may need to be conducted outside of the known habitat types and range. This species is federally listed under the Species at Risk Act (SARA), habitat may be subject to protections and prohibitions under the BC Wildlife Act and may also be governed under other provincial and federal regulations including the Fish Protection Act and Federal Fisheries Act as well as Regional and local municipal bylaws.

RESOURCES

For further information see:

Sources

A Field Guide to the Lowland Northwest. 2010. [Internet]. Slugs and Snails. - B.C. Conservation Data Centre. 2015. [Internet] Conservation Status Report: Allogona townsendiana. BC MoE. - BC Ministry of Environment, Lands and Parks. 1998. [Internet] Inventory Methods for Terrestrial Arthropods Standards for Components of British Columbia’s Biodiversity No. 40. Resources Inventory Branch for the Terrestrial Ecosystems Task Force. - BC Ministry of Environment. 2007. Draft Gastropod Best Management Practices Guidebook Oregon Forestsnail and Other Land Snails at Risk in the Coastal Lowlands. - Bureau of Land Management. 1999. [Internet] Field Guide to Survey and Manage Terrestrial Mollusk Species from the Northwest Forest Plan. Oregon State Office. - Burke, T.E. 1999. Management recommendations for terrestrial mollusk species. Cryptomastix devia, Puget Oregonian snail. V. 2.0. Prepared for Oregon Bureau Land Management. - COSEWIC. 2013. COSEWIC assessment and status report on the Oregon Forestsnail Allogona townsendiana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa . xii+87pp. - Durand, Ryan,. 2006. Habitat Assessment of the Endangered Oregon Forestsnail, Allogona townsendiani, In the Lower Fraser Valley of British Columbia. Taara Environmental. Prepared for the Fraser Valley Conservancy. - Edworthy, A.B., K.M.M. Steensma, H.M. Zandberg, and P.L. Lilley. 2012. Dispersal, home-range size, and habitat use of an endangered land snail, the Oregon forestsnail (Allogona townsendiana). Can. J. Zool. 90: 875–884. - Environment Canada. 2014. Recovery Strategy for the Oregon Forestsnail (Allogona townsendiana) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. XXI pp. + Appendix . - Environment Canada. 2010. Recovery Strategy for the Puget Oregonian Snail (Cryptomastix devia) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. iv pp. + Appendix. - Forsyth, Robert G. 2004. Land Snails of British Columbia. Royal BC Museum Handbook. Victoria: Royal BC Museum. 188 pages + [8] colour plates. - Ovaska, K. and L. Sopuck. 2003. Inventory of rare gastropods in southwestern British Columbia. Report prepared by Biolinx Environmental Research Ltd. for BC Ministry of Water, Land and Air Protection, Victoria, BC. - Ovaska, K. and L. Sopuck. 2003. [Internet] Terrestrial Gastropods as Indicators for Monitoring Ecological Effects of Variable Retention Logging Practices. Pre-disturbance Surveys at Experimental Sites, May –October 2002 Annual Progress Report. Biolinx Environmental Research Ltd. - Ovaska, K. and L. Sopuck. 2006. Surveys of potential Wildlife Habitat Areas for terrestrial gastropods at risk in southwest British Columbia, March 2006. Report prepared by Biolinx Environmental Research Ltd. for the Ministry of Environment, Victoria, BC. - Proulx, Gilbert et al. 2003. A Field Guide to Species at Risk in the Coast Forest Region of British Columbia. Published by International Forest Products and BC Ministry of Environment. Victoria (BC). - Steensma, Karen M.M. et al. 2009. [Internet] Life history and habitat requirements of the Oregon forestsnail, Allogona townsendiana (Mollusca, Gastropoda, Pulmonata, Polygyridae), in a British Columbia population. Invertebrate Biology. 1-11. 2009. - Wikipedia the Free Encyclopedia. 2010. [Internet] The Pulmonata snails. Updated December 29 2010. Sources

Credits

Prepared by: Pamela Zevit for the South Coast Conservation Program (SCCP), and Kristiina Ovaska and Lennart, Sopuck Biolinx Environmental, in partnership with: International Forest Products (Interfor), Capacity Forestry (CapFor). Funding was made possible through the Sustainable Forestry Initiative (SFI): http://www.sfiprogram.org/ Updated and revised by: Isabelle Houde, RPBio in consultation with the SCCP. Part of the National Conservation Plan, this project was undertaken with the financial support of the Government of Canada. Dans le cadre du Plan de Conservation National, ce projet a été réalisé avec l’appui financier du Gouvernement du Canada. Every effort has been made to ensure content accuracy. Comments or corrections should be directed to the South Coast Conservation Program: info@sccp.ca. Content updated March 2015. Image Credits: Oregon Forestsnail: Ryan Durand, Oregon Forestsnail (morph): Gord Gadsden, European Grove Snail: Pamela Zevit, Habitat: Ryan Durand. Only images sourced from “creative commons” sources (e.g. Wikipedia, Flickr, U.S. Government) can be used without permission and for non-commercial purposes only. All other images have been contributed for use by the SCCP and its partners/funders only.