COSEWIC Assessment and Status Report on the Pygmy Slug Kootenaia burkei in Canada - 2016

• Table of contents
• Assessment summary
• Executive summary
• Technical summary
• Wildlife species description and significance
  • Name and classification
  • Morphological description
  • Population spatial structure and variability
  • Designatable units
  • Special significance
• Distribution
  • Global range
  • Canadian range
  • Extent of occurrence and area of occupancy
  • Search effort
• Habitat
  • Habitat requirements
  • Habitat trends
  • Climate change
• Biology
  • Life cycle and reproduction
  • Physiology and adaptability
  • Movements and dispersal
  • Interspecific interactions
• Population sizes and trends
  • Sampling effort and methods
  • Abundance
  • Fluctuations and trends
  • Rescue effect
• Threats and limiting factors
  • Limiting factors
  • Threats
    • Climate change and severe weather (threat impact medium - low; scope: pervasive; severity: moderate - slight):
    • Invasive non-native species (threat impact medium - low; scope: restricted; severity: moderate to slight):
    • Logging and wood harvesting (threat impact: low; scope: restricted; severity: moderate):
    • Fire and fire suppression (threat impact low; scope: small; severity: moderate):
    • Roads and railroads (threat impact: low; scope: small; severity: moderate - slight):
    • Livestock farming and ranching (threat impact low; scope: small; severity: moderate - slight):
  • Cumulative effects
  • Number of locations
• Protection, status and ranks
  • Legal protection and status
  • Non-legal status and ranks
  • Habitat protection and ownership
• Acknowledgements and authorities contacted
  • Additional contacts
• Information sources
• Biographical summary of report writers
• Collections examined

• Figure 1. Pygmy Slug,Kootenaia burkei, from British Columbia. The length of the slug is ca. 10 mm.
• Figure 2. Global distribution of Pygmy Slug, Kootenaia burkei. Data sources: Leonard et al. (2003); Hendricks and Maxwell (2005); Hendricks pers. comm. (2013); Montana Government (2013); Table 1 (Canadian records).
• Figure 3. Canadian distribution of Pygmy Slug. Source of records from Table 1.
• Figure 4. Overview of sites surveyed for gastropods in and around the range of Pygmy Slug in southeastern British Columbia (see Table 2 for data sources within the area of interest).

• Table 1. Distribution records for Pygmy Slug,Kootenaia burkei, from Canada.
• Table 2. Summary of survey effort for terrestrial gastropods in southeastern British Columbia. Number of non-overlapping survey sites were calculated from GIS maps within the area of interest delineated in Figure 4.
• Table 3. Summary of IUCN threats calculator assessment for Pygmy Slug. Those threat categories that were not applicable to the species are omitted (hence the numbering of threats has gaps).

• Appendix 1. Summary of sites surveyed and gastropods found by Biolinx Environmental Research Ltd. (K. Ovaska and L. Sopuck) during fieldwork for this status report in September 2013 and for the Sheathed Slug (Zacoleus idahoensis) in September 2014 in the Kootenay region of British Columbia. additional support for surveys in 2014 came from BC Ministry of Environment. [editorial note: this table has been modified to remove geographic coordinates. the complete table can be obtained by contacting the COSEWIC secretariat.]
• Appendix 2. Threats calculator results, with notes, for Pygmy Slug based on conference call in May 2014.

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC. 2016. COSEWIC assessment and status report on the Pygmy Slug Kootenaia burkei in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 53 pp.

(Species at Risk Public Registry website).

COSEWIC would like to acknowledge Kristiina Ovaska and Lennart Sopuck for writing the status report on the Pygmy Slug in Canada. This report was prepared under contract with Environment Canada and was overseen by Joe Carney, Co-chair of the COSEWIC Molluscs Specialist Subcommittee.

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment and Climate Change Canada
Ottawa, ON
K1A 0H3

Tel.: 819-938-4125
Fax: 819-938-3984
E-mail: COSEWIC E-mail
Website: COSEWIC

Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur la Limace pygmée (Kootenaia burkei) au Canada.

Pygmy Slug - photo credit Kristiina Ovaska.

Pygmy Slug is the sole member of the newly described genus Kootenaia. As its common name implies, Pygmy Slug is very small with adults usually 9 - 14 mm long. The colour is from dark grey to tan with dense bluish flecking covering the mantle and tail; dark mottling is often present on the mantle. The tail is rounded (lacking a keel) with a series of parallel and oblique longitudinal grooves, which may resemble thin dark stripes. Pygmy Slug is a regional endemic to moist forests of the northern Columbia Basin, an area that contains many unique plants and animals.

The global distribution of Pygmy Slug extends from southeastern British Columbia through the Idaho Panhandle to northwestern Montana. In Canada, Pygmy Slug occurs in the Selkirk and Purcell sub-ranges within the Columbia Mountains in southeastern British Columbia. The species is known from 44 sites in the province; the number of sites may continue to expand with increasing search effort. Approximately 36% of the species' distribution is in Canada.

In British Columbia, the slugs occur mostly within the Interior Cedar-Hemlock biogeoclimatic zone, which is among the wettest areas in the interior of the province. The slugs have been found in moist mixed-wood and coniferous forests from low to mid-elevations (580 m - 1585 m), where they are commonly associated with riparian habitats along small tributary creeks. High substrate moisture and abundant shelter, such as provided by coarse woody debris or pockets of deep leaf litter, appear to be key habitat requirements. The slugs have been found from 40 - 50-year-old second growth to old growth (>200 years old) stands. Common trees at occupied sites included Western Redcedar and Black Cottonwood; the understorey often contained moisture-loving plants, such as Thimbleberry, Devil's Club, and Lady Fern.

The natural history of Pygmy Slug is poorly known. The slugs are hermaphroditic, but the exchange of sperm with other individuals rather than self-fertilization is probably the norm. The slugs lay small clutches of eggs, which are relatively large (10% or more of parent body length). The slugs are known to feed on lichens and fungi and probably also consume decaying organic matter in the duff layer. Most observations in British Columbia and the United States have taken place in autumn, when the slugs are active on the forest floor. Juveniles and an unknown proportion of adults probably overwinter. The generation time is approximately 1 year. The small size of the slugs may enable them to exploit small habitat patches provided that their requirements for moisture and shelter are met. Slugs in general are poor dispersers if not aided by humans or by wind or water; no such passive means of dispersal are known for Pygmy Slug, exacerbating the effects of habitat fragmentation on its distribution within the landscape.

Population sizes and trends of Pygmy Slug are unknown. Survey efforts have focused on elucidating the distribution of Pygmy Slug rather than on obtaining abundance estimates. Records for the species from British Columbia are from 2007 - 2015, precluding information on population trends.

The Canadian distribution of Pygmy Slug most likely reflects post-glacial expansion from refugia farther south. Its present distribution is probably limited by a short growing season and/or long and cold winters to the north, and drier forest types to the east and west. Low dispersal ability and requirements for moist habitats limit the speed at which the slugs can colonize new habitats.

Pygmy Slug populations are threatened by extreme events associated with climate change, introduced invasive species, fire and fire suppression, logging, roads, and livestock farming and ranching. The greatest threats to the slugs across their Canadian range are deemed to be from droughts and flood events, the frequency and severity of which are predicted to continue to increase under climate change scenarios. Invasive, non-native species that threaten slug populations include introduced gastropods, which are inadvertently spread by humans and which prey on or compete with native species, and other invertebrate predators such as ground beetles, which can be aggressive predators of slugs. Frequency and severity of wildfires is projected to increase with climate change. Due to their low mobility, gastropods are both unable to escape fire events by moving away and are slow to recolonize burnt areas. Logging is prevalent throughout the Pygmy Slug's range and continues to modify and fragment habitats. The effects of logging on slugs may be mitigated to some degree by riparian buffers, which are required along larger water courses containing fish, or which logging companies may leave voluntarily along small, fishless streams where they are not required. Logging roads and other resource roads also continue to fragment habitats.

Pygmy Slug has no official protection or status under the federal Species at Risk Act, B.C. Wildlife Act, or other legislation. Pygmy Slug is ranked by NatureServe as follows: Global status - G2 (imperilled); United States - N2 (imperilled); Canada - N1 (critically imperilled); Idaho: S2 (imperilled); Montana - S1S2 (critically imperilled to imperilled; BC:S1? (possibly critically imperilled). In British Columbia, the species is on the provincial red list of species at risk.

Across the Pygmy Slug's Canadian range, protected lands comprise approximately 20% of the land base and include several provincial parks, provincial Wildlife Habitat Areas established for other species, and other conservation lands. Pygmy Slug has not been recorded from any of the above areas with the exception of one site within a small conservation area. Most of the range and known sites are within provincial forestry lands.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Pygmy Slug, Kootenaia burkei, was described from specimens from northern Idaho in 2003 (type locality: Little Bumblebee Creek, Panhandle National Forest; Leonard et al. 2003). The species is the sole representative of the genus, placed within the large cosmopolitan family Arionidae (Leonard et al. 2003). An alternative classification by Bouchet and Rocroi (2005) raises all arionid subfamilies to full family status. Neither of these classifications is satisfactory, because current genetic studies do not support the monophyly of the more inclusive Arionidae or its subfamilies that have been investigated (Backeljau pers. comm. 2011).

Of other North American arionid genera, Kootenaia is most closely related to Prophysaon, but genetic divergence and comparative anatomy clearly set the two apart (Leonard et al.. 2003). In addition to Prophysaon, Burke (2013) placed Kootenaia and two newly discovered monotypic genera, Carionarion and Securicauda (Leonard et al.. 2011), in Anadenidae (Anadeninae in other classifications), but without explanation.

The current classification is as follows:

Phylum Mollusca
Class Gastropoda
Subclass Pulmonata
Order Stylommatophora
Suborder Arionoidea
Family Arionidae
(Subfamily Anadeninae)
Genus Kootenaia
Species Kootenaia burkei

The genus is named after the Kootenay First Nation, who historically occupied the land that encompasses the species' range (Leonard et al. 2003). The specific name honours Thomas Burke, a wildlife biologist who has worked extensively on terrestrial gastropods of the Pacific Northwest of the United States.

As its common name implies, Pygmy Slug is very small with adults usually 9 - 14 mm in extended length (Leonard et al.. 2003). In British Columbia (BC), the length of slugs when measured live ranged from 3 - 16 mm, including juveniles (Ovaska and Sopuck, unpubl. data 2007 - 2015). The body is slender, and the mantle covers approximately half of the length of the animal (Figure 1). The tail is rounded (lacking a keel) with a series of parallel and oblique longitudinal grooves. The grooves branch at the tip of the tail, forming small polygons, which are characteristic of the species (Burke 2013). The grooves on the tail may resemble thin dark stripes. It lacks an abscission line, such as found in taildroppers (Prophysaon species).

The colour is from dark grey to tan with dense bluish flecking covering the mantle and tail. Dark mottling is often present on the mantle but is occasionally lacking (Leonard et al. 2003). In BC, only unmottled slugs were found at some sites, whereas at most sites only mottled slugs were found (Ovaska and Sopuck, unpubl. data 2007 - 2015).

Internally, Pygmy Slug differs from other arionid slugs by its distal reproductive anatomy, commonly used in the classification and identification of gastropods. Compared to other arionids, it has an unusually reduced male component of the reproductive system and lacks a free epiphallus or vas deferens (Leonard et al.. 2003).

Genetic structure of Pygmy Slug populations is unknown. In BC, the species is known from scattered localities, most of which are south of 49.4°N. These and the more northern localities (up to 50.5°N) are separated by a minimum distance of 58 km (between Sites 4 and 6), and relatively great distances also separate the four northernmost localities from each other (42 km between Sites 5 and 9; 29 km between Sites 9 and 10; 38 km between Sites 10 and 4). Slugs in the northern localities are most likely isolated from each other and from those from farther south. Given the limited dispersal capabilities of the slugs and their affinity for very moist habitats, it is unlikely that there would be much genetic exchange among subpopulations outside single creeks or sub-drainages even within the southern portion of the range, where the species' distribution may be more continuous.

Pygmy Slug is known from a relatively small area within one COSEWIC National Ecological Area (Southern Mountain). There are no range disjunctions or other information that would suggest the presence of separate discrete and evolutionarily significant units within the Canadian subpopulation, but the genetic, anatomical, or ecological variability within the species has not been studied. The species is treated as one designatable unit.

Pygmy Slug is a regional endemic to moist forests of the northern Columbia Basin, an area that contains many unique plants and animals (Brunsfeld et al. 2001). This area extends from southeastern BC and northeastern Washington through the Idaho Panhandle to northwestern Montana. As one of a few genera of slugs endemic to western North America and the only representative of its genus, this species is of scientific interest for the study of glacial history and evolutionary relationships.

The global distribution of Pygmy Slug extends from southeastern BC through the Idaho Panhandle to northwestern Montana (Figure 2). On the Idaho Panhandle, the species has been reported from seven localities (five localities, Leonard et al.. 2003; Leonard pers. comm. 2013; two localities, Hendricks and Maxwell 2005; Hendricks pers. comm. 2013). There are 25 observations for Pygmy Slug in the Montana Natural Heritage Program database (current up to 11 April 2013; Montana Government 2013). These are from Lincoln, Sanders, and Mineral counties in the northwest of the state. Although there are no records, the species may occur in the extreme northeast of Washington State, based on the proximity of records to the British Columbia border. In Canada, the species has been found only in the Kootenay region of BC. Approximately 36% of the species' range is in Canada.

In Canada, Pygmy Slug occurs in the Selkirk and Purcell sub-ranges within the Columbia Mountains in southeastern BC (Figure 3). Its range lies between the east arm of the Columbia River (Lake Koocanusa) in the east and the Arrow Lakes in the west. The northernmost record (50.5 N°) is 62 km southeast of Revelstoke on the east side of Upper Arrow Lake.

Pygmy Slug was first discovered in BC in 2007, and subsequent targeted surveys from 2008 - 2015 have documented additional localities. There are now records from 44 sites in BC (sites are defined as localities >1 km from each other; Table 1). All but four sites are from below 49.58°N and within 64 km north of the international border. New sites continue to be found with increasing search effort; seven new sites were found in September 2013, 23 in 2014 as part of targeted surveys associated with the preparation of this status report and that for the Sheathed Slug, Zacoleus idahoensis, respectively, and six were found in 2015 during additional surveys for the BC Ministry of Environment, but the boundaries of the known range did not increase significantly. Additional sites are likely to exist, especially within the southern portion of the species' range.

Using the minimum convex polygon method based on known occurrence records, the extent of occurrence (EOO) is 15,552 km² with the international border with the United States as the southern boundary of the polygon.

The index of area of occupancy (IAO) based on a discrete grid for each observation record or group of records, is 180 km² (45 2 x 2 km grid cells). A more realistic IAO may be obtained by considering the entire creek with records of the species. Using this method, the continuous IAO is 1160 km² (290 2 x 2 grid cells) (EOO and IAO calculations by Jenny Wu, COSEWIC Secretariat). Additional, undocumented sites may exist that could further expand the IAO.

Little information exists on survey effort from the Kootenay region in BC before the 1990s. In his review of terrestrial gastropods of the Columbia Basin, Forsyth (1999) reported only four brief accounts that included terrestrial molluscs (from 1905 - 1945). Since the early 1990s, extensive surveys have been carried out in the Kootenay region, and over 700 sites have been surveyed (Table 2 ; Figure 4.). Most of these surveys specifically targeted terrestrial gastropods, with the exception of those by Copley and Copley, which were general arthropod surveys in which all gastropods encountered were collected and subsequently identified. Surveys have been carried out mostly in autumn, which generally is the best time for locating terrestrial gastropods, especially slugs; at this time, conditions are favourable for gastropod activity (wet and mild) and most slugs are mature, facilitating their detection.

Pygmy Slug was first found by Biolinx Environmental Research Ltd. in 2007; their surveys in subsequent years (2008, 2009, 2010, 2013, 2014, and 2015) resulted in further records for the species. Surveys in September 2013 and 2014 were in support of the preparation of this status report and that of the Sheathed Slug, respectively, and focused on habitats of Pygmy Slug; the Sheathed Slug occurs in similar habitats (see Appendix 1 for survey sites and species found). In an attempt to better delineate the Pygmy Slugs' distribution in BC in 2013, areas outside its known range to the west, north, and east were surveyed, progressing inward towards the presumed core range in the West Kootenays. The surveys in 2013 resulted in seven and those in 2014 in 23 new records for Pygmy Slug (Sites 9 - 38 in Table 1 and Figure 3) but only marginally increased the EOO. Additional surveys supported by the BC Ministry of Environment in 2015 (Ovaska and Sopuck 2015) resulted in six new sites but did not expand the EOO.

Across its global range, Pygmy Slug occurs in moist mixed-wood and coniferous forests, particularly in riparian habitats (Leonard et al.. 2003; Hendricks and Maxwell 2005; Ovaska and Sopuck 2009a,b). Leonard et al.. (2003) mentioned the close proximity of occupied sites to perennial water bodies, presumably because they contain suitable moist substrates. A predicted distribution model for Montana, based on the analysis of biophysical features at 20 known points and 60,000 random background points, showed that high suitability habitat was largely restricted to strips of riparian habitat along watercourses (Montana Government 2013). Observations in BC are also mostly from riparian habitats, frequently along fast-flowing creeks (Table 1). The riparian zone along these creeks was often confined to narrow strips in gullies, but in some cases the slugs were found in more expansive seepage areas with flatter terrain. Common understorey plants at occupied sites included Thimbleberry (Rubus parviflorus), Devil’s Club (Oplopanax horridum), Lady Fern (Athyrium filix-femina), Wild Sarsaparilla(Aralia nudicaulis), Twinflower (Linnea borealis), and Foamflower (Tiarella trifoliata). The slugs are not inhabitants of open shorelines or wetlands, such as Cattail (Typha latifolia) marshes.

Pygmy Slug occurs from low to mid-elevations in Idaho (640 m - 700 m asl (above sea level); Leonard et al. 2003), Montana (762 m - 1372 m asl for most records; reported as 2500’ - 4500’; Montana Government 2013), and BC (571 m - 1585 m asl; Table 1). Thirty six of the 44 (81.8%) Canadian records are from the Interior Cedar - Hemlock (ICH) Biogeoclimatic Zone (see Meidinger and Pojar 1991 for the classification of zones). Two sites are from the Montane Spruce (MS), two from the border of ICH and MS, and four from the Engelmann Spruce - Sub-alpine Fir (ESSF) zone (Table 1). The ICH zone occurs from low to mid-elevations in the lower slopes of the Columbia Mountains in southeastern BC, extending south to eastern Washington, Idaho Panhandle, and western Montana (Ketcheson et al.. 1991). It is flanked from above along an elevational gradient by the ESSF zone. The ICH zone is characterized by cool, wet winters and warm, dry summers with much of the soil moisture derived from snowmelt. The growing season (with above 0°C temperatures) extends from two to five months, depending on the latitude and elevation. It is among the wettest interior BC zones, sharing features with moist coniferous forests along the Pacific Coast; it is sometimes referred to as the Interior Wet Belt. Productive upland coniferous forests are prevalent throughout the landscape, but topography and soil conditions have resulted in a mosaic of wetter and drier forest types with relatively high over- and understorey diversity.

In BC, Pygmy Slug has been found in mixed-wood and coniferous forest stands of varying ages, ranging from 40 - 50-year-old second growth to old growth (>200 years old) stands (Table 1). Western Redcedar (Thuja plicata) was present in 74%, Black Cottonwood (Populus trichocarpa) in 61%, Engelmann Spruce (Picea engelmannii) in 58%, and Western Hemlock (Tsuga heterophylla) in 42% of the 38 occupied sites. Other tree species included Grand Fir (Abies grandis), Amabilis Fir(Abies amabilis), Subalpine Fir(Abies lasiocarpa), Paper Birch (Betula papyrifera), Western Larch (Larix occidentalis), and rarely Lodgepole Pine (Pinus contorta). A moderate understorey of diverse shrubs was usually present and often included moisture-loving species, such as Thimbleberry and Devil’s Club. Pockets of deeper leaf litter or relatively large amounts of coarse woody debris (mean = 14% coverage within 10 m from slug observations) were usually present (Ovaska and Sopuck, unpubl. data 2007 - 2014). Slugs were found in leaf litter, frequently within wet Cottonwood leaves, or under woody debris on the forest floor in moist situations. Common features among the sites included very moist substrates and abundant cover for the slugs to seek refuge. The availability of these microhabitat features may exert an overriding influence on the forest type or other coarse-scale habitat features.

Within the Pygmy Slug’s Canadian range, most suitable habitats are on provincial and private forestry lands subjected to ongoing logging. The removal of tree cover, building of forestry roads, and silvicultural activities associated with forestry have had the greatest impact on the availability of habitat within the species’ range, and logging continues to fragment and alter habitats. Ninety five percent of the known Pygmy Slug sites are within landscapes with ongoing logging (see Threats).

The Annual Allowable Cut (AAC) established for Crown lands on the three Timber Supply Areas encompassing the species’ range (Arrow, Kootenay Lake, and Cranbrook) has been relatively constant over the past four decades (MFLNRO 2014a). The latest AAC for these Timber Supply Areas, covering the next 5 - 10 years, suggests that a slightly lower level of harvest will be maintained. Most of the timber harvested in the past was from old-growth and from maturing forests on naturally disturbed areas. In the future, a greater proportion of the harvest will be obtained from regenerating second growth stands. In areas where the forest was logged 50 - 60 years ago (mainly lower to mid-elevations), conditions in maturing forests may allow the slugs to re-colonize some previously logged areas. Such increases in habitat availability will only partially compensate for the continuing degradation of habitat from logging. It is important to note, however, that logging does not occur, or is restricted, in parks, conservation lands, near fish-bearing streams, community watersheds, old-growth management areas, and special resource management zones that are scattered throughout the slugs’ range. The available land base for harvest for the Kootenay Lake Timber Supply Area, which encompasses over half of the slugs’ range, is estimated at 42% of productive forest land, after accounting for these conservation areas and other constraints to logging (MFLNRO 2014b). Additional timber is harvested each year on private lands and by woodlot licensees on Crown land (quantitative information could not be found).

Livestock grazing on Crown forest lands is confined mainly to the drier southern and eastern portions of the species’ range (iMapBC 2014). Range tenures on Crown lands are managed to avoid excessive grazing, potentially reducing impacts on riparian areas.

Land conversions for residential and industrial developments and for agriculture have resulted in the permanent loss of slug habitat mainly on private land at lower elevations, especially along river valleys, lake shores, and highways. However, the population density of the West Kootenay region is relatively low compared to other areas of southern BC, such as the Okanagan Valley and eastern Columbia Basin. Since 2001, the human population in the West Kootenay region has increased at a rate of only 1.3% per decade, reaching 64,379 people in 2011 (Columbia Basin Rural Development Institute 2012). Large population centres within the species’ range occur at Nelson and Creston, and a few much smaller communities occur at Fruitvale, Kaslo, Nakusp, Slocan Valley, Moyie Lake and Yahk. The relatively large cities of Castlegar, Trail, and Cranbrook lie just outside the species’ range.

Mining and quarrying activities are also present but involve a small percentage of the Pygmy Slug’s range. Mining and placer claims are common throughout the species’ range, especially in the south (Trail, Nelson, Salmo, Moyie Lake), and central (New Denver/Silverton) areas, and several mineral exploration projects are underway (Grieve 2010). Although new mines could be developed in the future, no mining projects are currently being assessed in the slugs’ range (iMapBC 2014). However, immediately to the northeast near Trout Lake, the reopening and expansion of a mine for the mineral molybdenum is under review. Extensive habitat degradation from air pollution has occurred over the last 100 years in the vicinity of the smelter in Trail, on the periphery of the species’ range.

Reservoirs associated with hydroelectric development have flooded large areas of potential slug habitat over the past century (Kootenay Lake and Pend D’Oreille within the range; Arrow Lakes, Duncan Lake, and Lake Koocanusa on the periphery). Several projects are underway to upgrade hydro power stations, but no large-scale creation or expansion of reservoirs are planned in the near future (iMapBC 2014). Power transmission line corridors are relatively common in the species’ range and several more will likely be built to serve expanded hydro operations. Over 20 smaller-scale run-of river hydroelectric projects are also proposed or approved (1 is operational, 8 are approved and the remainder are under review) within the species’ range (Wildsight 2014).

Recreational developments such as ski areas, tourist resorts and campgrounds are scattered over the Pygmy Slug’s range, but infrastructure is limited at present. No large tourist developments are currently being assessed for the area (iMapBC 2014). The proposed Jumbo Glacier Resort development is located northeast of the species’ range. Widespread recreational activities in the area include use of all-terrain vehicles, snowmobiles, and mountain bikes.

Previous and ongoing habitat fragmentation due to all human activities combined, especially at lower elevations, is a concern for Pygmy Slug. Fragmentation has occurred as a result of extensive logging, increased frequency of catastrophic wildfires (due to buildup of fuels to unnatural levels), the creation of large hydroelectric reservoirs, highway construction, urbanization, and land conversions for agriculture. The ICH biogeoclimatic zone is prone to periodic fire disturbance but to a lesser degree than drier biogeoclimatic zones in the southern interior of BC (Biodiversity Guidebook 1995). Logging on the other hand selectively removes high-value timber in moist, productive sites, resulting in fewer refuges being available to slugs after logging.

The West Kootenay Resilience Program (undated) has produced a series of documents addressing climate change and its implications in the West Kootenay region of British Columbia. Pygmy Slug occurs mainly in the south and middle subzones of the West Kootenays, and along the southern fringe of the north subzone. All models and scenarios examined project higher mean seasonal temperatures that increase progressively by 2020s, 2050s and 2080s (Utzig 2012a). By 2080, winters are predicted to be 2 - 5 C° warmer and 10 - 25% wetter and summers 3 - 7°C warmer and up to 30% drier than during the baseline period (poorest performance models excluded). Associated changes that have implications for Pygmy Slug include increase in summer moisture stress, potential increase in wildfires and insect and disease outbreaks that would reduce forest cover, and changes in seasonal stream flow patterns as a result of reduced snow-packs and summer droughts, which would alter the riparian areas inhabited by the slugs. Increase in the magnitude and frequency of extreme events, such as high intensity rain events, severe droughts, and wind storms, are also predicted (Utzig 2012a).

Wang et al. (2012) examined climate change effects on BC’s 16 biogeoclimatic zones, which are based on large-scale climate gradients and widely used to classify ecosystems in the province (Meidinger and Pojar 1991). Models showed that climate envelopes supporting this zonation have already shifted since the 1970s (Wang et al. 2012). Projected into the future (2020s, 2050s, and 2080s) and across the entire province, the models predict a substantial expansion of moist continental cedar-hemlock forests, typical of the ICH zone where Pygmy Slug is found, potentially expanding this zone up to three-fold by 2080, with the ICH zone becoming the most common forest type in the province over the long term (Wang et al.. 2012). At a regional scale, the projections are more complex and influenced by topography and local factors (Utzig 2012b). Climate models for the West Kootenays indicate that the ICH zone will expand over the long term under one of three climate change scenarios examined (“Warm/Moist” scenario), while it is predicted to be largely displaced by the Coastal Western Hemlock and Coast Transition-type ecozones, which also consist of moist forests, under the “Hot/Wet” scenario, and by the drier Grassland-steppe and Ponderosa Pine woodlands under the “Very Hot/Dry” scenario (Table 3.1 and Figure 3.5 in Utzig 2012b). The expansion of moist and wet forest types favourable to Pygmy Slug are mostly in the northern portion of the species’ range and/or at higher elevations (>1000 m asl). Correspondingly, suitable habitat would shrink in the southern portion of the range and at lower elevations. Whether Pygmy Slug would be able to spread northwards and upwards in pace with the ecosystem shifts to take advantage of the newly available habitats is questionable. The changes may be driven largely by extreme climatic events such as summer droughts or storms and mediated through pest outbreaks, fires or other disturbances rather than occurring through gradual transition (Pojar 2010; Utzig 2012b); also, novel bioclimatic zones may emerge with new combinations of seasonal climatic variables (Utzig 2012b), increasing the unpredictability of the projections.

Historical fire regimes and projections for the future under climate change have been examined in detail for the West Kootenays (Utzig et al.. 2011). Over the first half of the 20th century, fires occurred almost annually and burned large areas, especially in the southern part of region, with annual burn exceeding 30,000 ha in some years (Figures 2 and 3 in Utzig et al.. 2011). A threshold appeared to have been reached around 1940 with greatly diminished annual fire frequency until the 1980s, with slight increases thereafter. The decrease was associated with a cooling trend in spring and summer and fire suppression efforts in the latter half of the century. Projected into the future, all models showed increases in the area burned with the greatest increases in the north sub-region. Reflecting uncertainty, there is much variability in the outputs from the different models about the magnitude of the increase in fire frequency, but by 2050 the mean projected increase could be up to 300-fold in the north, 30-fold in the middle, and 15-fold in the south subzone. The projected increases are more modest by 2020, and only in the north exceed historical values recorded since the beginning of the 20th century (Figure 9 in Utzig et al.. 2011).

Little information is available on the biology of Pygmy Slug, apart from natural history notes in the description of the species (Leonard et al.. 2003) and information associated with subsequent distribution records from Montana and BC (Montana Government 2013; Ovaska and Sopuck, unpubl. data 2007 - 2014). Some general information can be gleaned from the biology of other arionid slugs.

Pygmy Slug is hermaphroditic, possessing both female and male reproductive organs (Leonard et al.. 2003). However, like most pulmonate gastropods, individuals probably exchange sperm (Tompa 1984); there is no evidence of self-fertilization in this species.

There is only one observation of egg-laying; a slug from Idaho laid a clutch of three eggs in captivity in July (Leonard et al.. 2003). The oval eggs were large (1 x 1.8 mm versus 9 mm body length of the parent) and hatched seven weeks later in September. In Idaho, adults have been found both in spring and autumn (Leonard et al.. 2003). The Montana Natural Heritage Program database contains 25 records of Pygmy Slug from September to November, with most records from October (Montana Government 2013). In BC, adults (based on body length > 9 mm) and juveniles have been found from September to October (Table 1), but only a few targeted surveys have been conducted at other months. The smallest juveniles were 2 - 3 mm in length and were probably newly hatched.

Juveniles presumably overwinter, but the proportion of adults that do so is unknown. The generation time is probably 1 year or slightly more, based on the small body size of the adults and relatively short life spans of arionid slugs in general.

Pygmy Slug is often associated with riparian habitats and appears to require a high level of environmental moisture. The degree to which it tolerates habitat disturbance is largely unknown, but it is most likely adversely affected by human activities that alter the hydrology of occupied sites and result in drying or flooding of the forest floor. Due to its small size and resulting ability to exploit moist microhabitats, subpopulations may persist in small remnant habitat patches, provided that moisture requirements are met. However, isolated habitat patches from where the species becomes extirpated are unlikely to be repopulated through immigration, at least over the short term.

Movements and dispersal of Pygmy Slug are unknown. Land snails in general have poor dispersal abilities if not aided by humans or transported by other passive means, such as wind or water (review in Cordeiro 2004). No passive means of transport are known for Pygmy Slug, but it is conceivable that the slugs may inadvertently attach to the fur of mammals such as bears, as speculated for other slugs (COSEWIC 2012).

Leonard et al.. (2003) reported observations of Pygmy Slugs feeding on lichen growing on coarse woody debris on the forest floor. The slugs may also feed extensively on fungi, as reported for other slugs (Prophysaon coeruleum: McGraw et al. 2002), potentially aiding dispersal of their spores. In BC, Pygmy Slugs have been found on fungi growing on downed wood (Ovaska and Sopuck, unpubl. data 2013; Figure 1). Pygmy Slugs probably act as prey for a variety of forest floor invertebrates, such as ground beetles (Coleoptera: Carabidae) and centipedes (Chilopoda). Due to their small size, they are probably not actively hunted by small mammals but may be consumed by birds that forage on the forest floor.

In BC, survey efforts have focused on elucidating the distribution of Pygmy Slug rather than on obtaining abundance estimates (see Search Effort). Methods have consisted mainly of one or more observers walking through the area of interest and searching the forest floor, concentrating on microhabitats deemed important for gastropods, such as decaying logs, sloughed-off bark, stumps, rocks, or other cover-objects or moist refuges, and accumulations of moist leaf litter. Some of the surveys, including all of those during which Pygmy Slug have been found, included the amount of time spent in intensively searching suitable microhabitat as an index of search effort (Table 1 and references therein).

Population sizes and densities are unknown, but the slugs appear to be patchily distributed in the landscape, even within apparently suitable habitats. Most observations in BC have consisted of 1 - 3 slugs per site, but concentrations of 8 - 16 slugs, including juveniles, were found on four occasions (at Sites 2, 8 15, and 34 in Table 1) within an area of approximately 10 - 15 m in diameter. At all sites, the species was usually detected within the first 10-15 minutes of search time or not found at all.

Comparisons of Pygmy Slug records with those of other native forest slugs in the Kootenay region of BC provide some information on their relative rarity. During surveys by Biolinx Environmental Research Ltd in 2007 - 2014, Pale Jumping-slug (Hemphillia camelus) was widespread and abundant when compared to Pygmy Slug; Magnum Mantleslug (Magnipelta mycophaga; COSEWIC status: Special Concern) was more widespread but found only at a few scattered sites; Reticulate Taildropper (Prophysaon andersonii) was found less frequently but has a wide distribution in BC, extending well beyond the Kootenays; Sheathed Slug (Zacoleus idahoensis; COSEWIC 2016) was found only infrequently and in the southern portion of Pygmy Slug’s range.

Pygmy Slug was discovered only recently (2007), and no information exists of fluctuations or population trends in Canada or the United States.

The closest Canadian records of Pygmy Slug to the international border with the United States are only 4 km north from eastern Washington State (Site 11 in Table 1 and Figure 3) and 7.6 km north from western Montana (Site 2 in Table 1 and Figure 3). The species has not been documented from Washington, but the habitat south from the BC border appears to be relatively continuous. In western Montana, there are records of the species from within approximately 5 km of the international border (Montana Government 2013). The examination of imagery from Google Earth® shows large clearcuts in the intervening area on the Canadian side, which would impede movements of slugs. However, some interchange of individuals with the United States could occur both through the east and west portions of the Pygmy Slugs’ Canadian range over longer time frames within the constraints of poor dispersal abilities of the slugs and impediments posed by human land uses, such as roads, clearcuts, and settlements.

Pygmy Slug exists at the northern limits of its global distribution in southeastern BC, where its distribution most likely reflects post-glacial expansion from refugia farther south. Its northward expansion is probably limited by a short growing season and/or long and cold winters. Drier forest types to the east probably limit its eastward expansion and explain the absence of the species from most of the East Kootenays. Complex topography and the resulting mosaic of drier and wetter habitats probably constrain its distribution both within and among watersheds. Logging has further fragmented habitats and reduced permeability of the landscape to movements and gene flow. Low dispersal ability and requirements for moist habitats limit the speed at which the slugs can colonize new habitats.

The IUCN threats calculator (Master et al. 2009) was used to assess threats to the Pygmy Slug (Table 3; Appendix 2). Threats were considered across the entire Canadian distribution of the species to account for possible undocumented sites, but using threats and land uses at known sites as guidance. The threats calculator method consists of scoring the scope, severity, and timing for each standard threat category; the overall threat impact is then computed from these ratings.

The overall threat impact for Pygmy Slug was scored as “high - medium”, where the range reflects uncertainty. Under the “high” impact scenario, there were two medium and four low impact threats, whereas under the “medium” impact scenario, there were six low impact threats. The two highest ranking threats, “climate change and severe weather” and “invasive, non-native species”, have much uncertainty associated with both the scope within the next ten years and the severity of the impacts on slug populations. Headings in the following narrative correspond to categories (or subcategories) of the threats calculator, in the approximate order of their perceived importance.

Severe weather and increased frequency of extreme events associated with climate change were considered pervasive in scope for Pygmy Slug (71 - 100% populations affected), because the entire Canadian range of the species is likely to be influenced by the same broad weather patterns. However, terrain and habitat features could modulate impacts on the slugs among watersheds and sites. The main impacts on the slugs will probably accrue from droughts and flood events, both of which are predicted to increase in frequency and severity under climate change scenarios (Utzig 2012a). Because of its reliance on habitats with high moisture, prolonged and severe summer droughts may be particularly devastating to local subpopulations of Pygmy Slugs both directly by increasing mortality and indirectly by reducing the length of time available for growth and reproduction. Series of years with droughts that extend well into the autumn are expected to be particularly detrimental. The Kootenay region of British Columbia experienced Stage 2 drought conditions (dry) during May, June and July 2015, followed by Stage 3 conditions (very dry) from August to mid-September (BC Ministry of Forests, Lands and Natural Resource Operations 2015). Four sites where the species had been found in previous years were revisited in late September 2015; Pygmy Slug was found at two of these sites (Ovaska and Sopuck 2015). The drought may have reduced the abundance or detectability of the slugs, but the sample size is too small to draw reliable conclusions. The reduction in detectability was particularly evident at a site on the eastern periphery of the species’ range, where nine Pygmy Slugs were found in 2013 but none in 2015. Whether the slugs were deeper in the substrate or had suffered declines is unknown.

Increased frequency of flooding events could result in mortality or displacement of slugs living close to water courses and could scour riparian areas of the duff layer and refuges. While flooding might be of short duration along mountain streams, its effects are potentially more devastating where the slugs inhabit flatter terrain that may remain inundated for longer periods.

Much uncertainty exists about the severity of the impacts of climate change and severe weather on Pygmy Slug, as reflected by the wide range of assigned threats calculator ratings. However, a precautionary approach is warranted because of the potentially widespread and serious nature of this threat. With a few exceptions, impacts associated with climate change are unstudied for terrestrial gastropods. The studies that do exist have focused on habitat shifts along altitudinal gradients in Europe and have projected range shrinkages and subpopulation declines for high elevation species (Müller et al. 2009) and upward altitudinal shifts for lower elevation species (Baur and Baur 2013). For Pygmy Slug, it is likely that proximate factors such as droughts that drive ecosystem shifts are more important than the shifts themselves; with its low dispersal capability and reliance on moist habitats, the slugs may not be able to track ecosystem shifts that may occur.

Non-native gastropods and other invertebrates pose a threat to native gastropods through competition for food and shelter, predation, and/or alteration of ecosystem processes and habitats. Over 20 species of non-native gastropods have been recorded from BC (Forsyth 2004). Although mostly found in disturbed areas, many are spreading into forested habitats. Humans continue to facilitate the spread of introduced gastropods across the province, where they can be found in most areas frequented by humans, including picnic sites, campsites, and rest stops along highways. Other widely introduced invertebrates in BC include carabid beetles (Coleptera: Carabidae), which can prey on gastropods (Symondson 2004), and earthworms, which can reduce or remove the duff layer through their actions with potentially detrimental effects on native forest floor invertebrates (Addison 2009). In the West Kootenays, introduced gastropods were found at only two of 38 known sites occupied by Pygmy Slug (Sites 1, 10), and were probably also present at at least two additional sites, readily accessed by recreational users (Sites 6, 11). Increased human access to the backcountry associated with resource extraction activities and an expanding road network will facilitate the spread of these and other introduced invertebrates to new areas.

Much uncertainty exists with the severity of impacts of introduced species on Pygmy Slug, as reflected by the wide range of threats calculator ratings. Introduced gastropods pose a threat to native gastropod faunas around the world (Mahtfeld 2000), but their effects in terrestrial habitats are generally poorly documented. An exception is island faunas, where alien invertebrate predators and competitors, including other gastropods, have been largely responsible for the demise of native land snail faunas (e.g., Hawaii: Hadfield et al. 1993; South Pacific: Cowie 2001). In BC, introduced gastropods include scavengers/predators, such as Boettgerilla pallens and Oxychilus species, and herbivores/detrivores, such as species of Arion that can become exceedingly abundant in suitable habitats and could have a demographic advantage over native species in competition for resources. Carabid beetles are known predators of terrestrial gastropods in both natural and disturbed habitats, and slugs form a large portion of the diet of many generalist carabids (Symondson 2004). While snail predators tend to be specialized, predation on slugs does not appear to require specific adaptations by the beetles. In the United Kingdom, carabid beetles with a large proportion of slugs in their diet were relatively large with strong mouth parts and had the ability to forage widely (Tod 1970, cited in Symondson 2004). Defences of slugs against carabid attacks include the production of copious amounts or highly viscous mucus, repellants or toxic chemicals in the mucus or tissues, and tail autotomy (Symondson 2004). Pygmy Slug is not known to possess any of these mechanisms and may rely on crypsis and small size to avoid predation. However, it may be defenceless against aggressive introduced predators, such as the carabid beetle Carabus granulatus, which was observed preying on native slugs (Hemphillia camelus and Prophysaon andersonii) in the West Kootenays during fieldwork for this report; the ability to autotomize the tail appeared to provide no advantage to P. andersonii (Ovaska and Sopuck, unpubl. data 2013). The site where C. granulatus was observed (Site 2013-13 in Appendix 1) is only 2.5 km from a known Pygmy Slug site.

Most of the Canadian distribution of Pygmy Slug is within lands used for forestry. Large areas of the landscape have already been subjected to clear-cut and selective logging, and new logging continues to degrade habitat and fragment the species’ range, but quantitative data on the amount of habitat affected over the next ten years are lacking. Harvesting of maturing second growth has started in the region, also at largely unknown rates. Effects of logging on the slugs would result from changes in moisture and temperature regimes on the forest floor due to canopy removal and from disturbance to the understorey vegetation and forest floor structure.

Based on visual estimation from forestry layers in iMapBC (2014) and Google Earth (2014; imagery from 2003-2013), 95% of the known Pygmy Slug sites are within landscapes with ongoing logging, but it is unknown how many new sites will actually be logged over the next ten years. Only one site (Site 35 in Table 1) is secure from logging. Pygmy Slugs may be able to persist in small forest patches or riparian buffers within logged sites, at least over the short term, as evidenced by their presence in such habitats within recently logged landscapes. However, it is conceivable that there is a time lag before the full effects of recent logging are manifested, and the long-term viability of subpopulations in these habitats is unknown.

Within logged landscapes, Pygmy Slug could receive protection from forested riparian buffers. Riparian buffers are required along larger, fish-bearing streams under the BC Forest and Range Practices Act, but there are no such requirements for small, fishless streams (S6 streams), along which Pygmy Slugs are usually found; nor are there required buffers for other non-classified drainage features, such as seepages. However, some forestry companies operating in the Kootenay region voluntarily leave buffers along all streams, regardless of their size or status (Stuart-Smith pers. comm. 2014). Even with voluntary efforts, many small streams are likely to be impacted, increasing the scope. In addition to riparian buffers, there is usually a 7 m wide no-machinery zone along creeks, although trees may be taken from this zone. Pygmy Slug habitat along creeks in steep-sided gullies would be buffered, because the terrain is usually too steep for timber harvesting (Stuart-Smith pers. comm. 2014).

Fires are harmful to terrestrial gastropods by causing direct mortality and, perhaps more importantly, by altering habitat through reduction in shelter and food sources over the short and longer term (Jordan and Hoffman Black 2012). Due to their generally low mobility, gastropods are both unable to escape fire events by moving away and are slow to recolonize burnt areas. In the West Kootenay region, more frequent and severe fires are predicted as climate change proceeds (see Habitat Trends). The size and intensity of the burn are expected to greatly influence the outcome for gastropod populations; greatest effects are likely when the burn covers a large continuous area and extends deep into the ground, while smaller, discontinuous, and less severe burns would be less devastating. In the latter situation, gastropods could survive in underground refugia or unburned habitat patches, which could serve as sources for recolonization once the habitat regenerates. Riparian areas along small creeks inhabited by the slugs may be somewhat protected from fires that sweep the landscape, especially in steep gullies and on north-facing slopes; unburned streamsides within large recent burns were observed at such sites during fieldwork for this report (Ovaska and Sopuck, unpubl. data 2007-2013).

Several studies have reported negative effects of fire on species richness and/or abundance of terrestrial gastropods (review in Jordan and Hoffman Black 2012). Snails seem to be particularly vulnerable (Anderson 2004; Duncan 2005), but effects on slugs have also been reported (Duncan 2005). In southwestern Oregon, both the distribution and abundance of four species of terrestrial gastropods studied were reduced after low-intensity prescribed fires (Duncan 2005). The effects were more severe on snails than on slugs (e.g., Blue-grey Taildropper, Prophysaon coeruleum), but slugs were not found at over a quarter of the sites that supported them during pre-fire surveys. The author suggested that at sites with continued persistence, slugs survived in deep fissures in coarse rock substrate or other underground refuges and suggested that the distribution of microhabitats that allow for vertical movements is important for the long-term viability of slug populations within the landscape.

Logging roads are prevalent throughout the Pygmy Slug’s range, and a major highway is within 1 km of four known sites (Sites 1, 7, 10 and 34). Visual examination of the landscape within 1 km radius from each known site, based on iMapBC (2014), estimated road density as “high” at six sites (Sites 10, 11, 14, 18, 22, and 32) and low at seven sites (Sites 6, 12, 13, 26, 27, 34 and 35); the remaining 25 sites were rated as “medium” with respect to road density.

New roads associated with forestry and other types of resource extraction are likely to increase over the next ten years with the expansion of these activities to new areas. Adverse effects on slugs from new roads result from habitat loss on the road corridor and through edge effects that can extend far into the forest, from possible changes to drainage patterns, desiccation from increased wind and solar radiation and from habitat fragmentation through barriers to movements. Adverse effects on slugs may also accrue from traffic on existing roads, such as dust that extends into the surrounding forest, or reactivation of roads in previously logged areas. Road corridors may exacerbate effects of droughts through edge effects. However, because resource roads are usually not placed along water courses, their effects on Pygmy Slugs in riparian habitats are limited to stream crossings. Therefore, the scope for this threat was rated as “small” (1 - 10% of slugs affected) and would hover around the lower end of the spectrum (around 1%).

Livestock are usually not free-ranged in dense, steep forested areas characteristic of the West Kootenays, and grazing tenures within the Pygmy Slug’s range occur mostly in drier more open forests in the south and east (iMapBC 2014). However, where free-ranging does occur, cattle and other livestock tend to concentrate in riparian areas, where they can affect slug habitat by compacting soils and removing understorey vegetation. Signs of cattle use were observed at or in the vicinity of 5 (13%) of known sites occupied by Pygmy Slug (Appendix 2).

Cumulative impacts result from additive or synergistic interactions among two or more threats, which would elevate the level of the overall threats. For Pygmy Slug, cumulative effects are likely to accrue from interactions among climate change and severe weather, fire and fire suppression, and forestry. Increased frequency and severity of prolonged summer droughts is likely to exacerbate the effects of logging (both recent and planned) and wildfires on the slug’s habitat. For example, narrow forested riparian buffer zones that would otherwise support viable Pygmy Slug subpopulations may no longer do so under prolonged and more frequent droughts. Severe droughts will probably increase the frequency, areal extent, and intensity of wildfires, potentially resulting in the loss of subpopulations from local areas. Both interactions would increase habitat fragmentation and isolation of subpopulations of Pygmy Slugs. Any activities that increase human access, such as resource roads, increase the potential for the introduction or spread of invasive, non-native gastropods and other invertebrates. Climate change and forest disturbance are also expected to facilitate their spread with largely unknown and untracked but potentially serious impacts on native gastropod faunas.

The greatest plausible threats to Pygmy Slug, as per the threats calculator analysis, are from climate change and severe weather and from invasive and introduced species. Considering each occupied watershed as a separate location, where all slugs could be affected by a single threatening event (severe drought), then there are at least 28 locations; the exact number depends on how sub-drainages are delineated and which sites are combined; additional occupied watersheds may exist. Although droughts are likely to be broad-scale across the entire region, impacts on the slugs may be better assessed at watershed scale, depending on amount of logging in the landscape, width of riparian buffers, availability of coarse woody debris, and other site-specific conditions that affect refuges for slugs and moisture regimes on the forest floor. Similarly, effects of introduced invasive species could be considered at the watershed scale, as they may spread through a watershed after an initial introduction.

Currently, Pygmy Slug has no official protection or status under the federal Species at Risk Act, B.C. Wildlife Act, or other legislation.

NatureServe (2013) provides the following global, national, and sub-national rankings for Pygmy Slug: Global status - G2 (imperilled); United States - N2 (imperilled); Canada - N1 (critically imperilled); Idaho: S2 (imperilled); Montana - S1S2 (critically imperilled to imperilled; BC - S1? (possibly critically imperilled). In BC, the species is on the provincial red list of species at risk. In Montana, Pygmy Slug is designated as a Species of Concern (Montana Government 2013).

Roughly 10% of the Canadian range of Pygmy Slug is within provincial parks, including Valhalla, Kokanee Glacier, West Arm, Lockhart Creek, Kianuko, Stagleap, Champion Lakes, and Kootenay Lake provincial parks (visual estimation from iMapBC protected areas layer). In March 2014, Bill 4, an amendment to the Parks Act was passed by the BC government. The bill allows for exploratory drilling, ore sampling and road building within BC Parks. Approximately 5% of the range is within provincial Wildlife Habitat Areas established for other species, or in other conservation lands (information from iMapBC). Additionally, the Darkwoods Conservation Area, a large (55,000 ha) private property purchased by Nature Conservancy Canada in 2008 located between Nelson and Kootenay lakes and adjacent to West Arm Provincial Park and Midge Creek Wildlife Management Area, is within the core range of Pygmy Slug. This area encompasses 4% of the species’ range, bringing the total percentage of protected lands to 19%. An additional 25% of the range is within community watersheds that receive some degree of protection. Pygmy Slug has not been recorded from any of the above areas with the exception of Site 11, which is within a small conservation area associated with a BC Hydro development. Additionally, Site 35 is within and Site 6 is immediately adjacent to Champion Lakes Provincial Park. Limited surveys within the Darkwoods Conservation Area (Copley, unpubl. data 2010 - 2012) have failed to locate Pygmy Slug.

Much of the range and most records of Pygmy Slug are from provincial forestry lands. As a provincially red-listed species impacted by forest and range practices, Pygmy Slug is potentially eligible for management under the Identified Wildlife Management Strategy of the B.C. Forest and Range Practices Act. However, it is not listed as identified wildlife at present, and hence no specific management measures are available or required. Riparian reserves around fish-bearing streams required under the act may help protect Pygmy Slugs persist in logged areas, but no such protection is required around smaller, non-fish-bearing (S6) streams. Some forest companies voluntarily leave reserve areas around all water courses, including S6 streams (Stuart-Smith pers. comm. 2014).

The report writers contacted the following people in the preparation of this report - we thank all who provided information:

COSEWIC Secretariat:
Neil Jones
Julie Perrault
Sonia Schnobb
Jenny Wu

Canadian Wildlife Service:
Syd Cannings
David Cunnigton
Rhonda Millikin

Parks Canada:
Patrick Nantel

B.C. government representatives:
Ted Antifeau
Dave Fraser
Jennifer Heron

B.C. Conservation Data Centre:
Lea Gelling

• Claudia Copley, Collections manager (arthropods), Royal B.C. Museum, Victoria, B.C.
• Robert Forsyth, Research Associate, Royal B.C. Museum, Victoria, B.C.
• Heidi Gardner, Collection Manager (mollusks), Royal British Columbia Museum, Victoria, B.C.
• Paul Hendricks, Montana Natural Heritage Program
• William Leonard, Biologist, Olympia, Washington
• Dwayne Lepitzki, Biologist, Banff, Alberta

Additionally, the following people participated in a threats calculator conference call for the species in February 2014: Ian Adams, Joe Carney, Dave Fraser, Andrew Hebda, Gerry Mackie, Rob McQuarry, Dwayne Lepitzki, Julie Perrault, Kristiina Ovaska, Lennart Sopuck, Kari Stuart-Smith, Charlene Strelaeff. Jenny Wu prepared maps and provided EOO and IAO calculations Funding for the report came from Environment Canada.

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Kristiina Ovaska, Ph.D., M.Sc., received her doctoral degree in biology from the University of Victoria, after which she completed two post-doctoral studies in animal behaviour and population biology with McGill University and University of British Columbia, respectively. Presently, she is a partner in Biolinx Environmental Research Ltd., biologist with Habitat Acquisition Trust, and research associate at the Royal British Columbia Museum. Her experience with terrestrial gastropods includes research into effects of forestry practices, studies on patterns of abundance and distribution of species at risk, and numerous surveys in different parts of British Columbia, including the Kootenays. She has prepared status reports, recovery documents, and best management practices guidelines for terrestrial gastropods. Her photographs of gastropods appeared in the Royal B.C. Museum Handbook “Land Snails of British Columbia” by R. Forsyth. She is the author of more than 40 publications in the refereed scientific literature, including several papers on terrestrial gastropods.

Lennart Sopuck, M.Sc., RPBio, has studied a wide variety of wildlife species over the past 30 years. His expertise includes assessing and mitigating effects of various human activities on wildlife, including species at risk. Together with Dr. Ovaska, he is a partner of Biolinx Environmental Research Ltd. and has conducted numerous survey and research projects on terrestrial gastropods of British Columbia. He is co-author of several status reports, recovery strategies, a multi-species action plan, and management documents for terrestrial gastropod species.

Collections at Royal British Columbia Museum were queried, but no specimens were examined.