Recovery Strategy for the Blue-grey Taildropper (Prophysaon coeruleum) in Canada - 2016 [Proposed]
- Part 1 – Federal Addition to the Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia, prepared by Environment and Climate Change Canada
- Part 2 – Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia, prepared by the Blue-grey Taildropper Recovery Team for the British Columbia Ministry of Environment.
Part 1 – Federal Addition to the Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia, prepared by Environment and Climate Change Canada
Environment and Climate Change Canada. 2016. Recovery Strategy for the Blue-grey Taildropper (Prophysaon coeruleum) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. 2 parts, 20 pp. + 36 pp.
For copies of the recovery strategy, or for additional information on species at risk, including the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) Status Reports, residence descriptions, action plans, and other related recovery documents, please visit the Species at Risk Public Registry.
Cover illustration: © Kristiina Ovaska (with permission)
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Recovery Strategy for the Blue-grey Taildropper (Prophysaon coeruleum) in Canada 2016
Under the Accord for the Protection of Species at Risk (1996), the federal, provincial, and territorial governments agreed to work together on legislation, programs, and policies to protect wildlife species at risk throughout Canada.
In the spirit of cooperation of the Accord, the Government of British Columbia has given permission to the Government of Canada to adopt the Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia (Part 2) under Section 44 of the Species at Risk Act (SARA). Environment and Climate Change Canada has included a federal addition (Part 1) which completes the SARA requirements for this recovery strategy.
The federal recovery strategy for the Blue-grey Taildropper Slug in Canada consists of two parts:
Part 1 – Federal Addition to the Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia prepared by Environment and Climate Change Canada.
Part 2 – Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia, prepared by the Blue-grey Taildropper Recovery Team for the British Columbia Ministry of Environment.
The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c. 29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress within five years after the publication of the final document on the SAR Public Registry.
The Minister of Environment and Climate Change is the competent minister under SARA for the Blue‑grey Taildropper and has prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. To the extent possible, it has been prepared in cooperation with the Province of British Columbia as per section 39(1) of SARA. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub-sections 41(1) or (2)). The Province of British Columbia provided the attached recovery plan for the Blue‑grey Taildropper (Part 2) as science advice to the jurisdictions responsible for managing the species in British Columbia. It was prepared in cooperation with Environment and Climate Change Canada.
Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment and Climate Change Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Blue-grey Taildropper and Canadian society as a whole.
This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment and Climate Change Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.
The recovery strategy sets the strategic direction to arrest or reverse the decline of the species, including identification of critical habitat to the extent possible. It provides all Canadians with information to help take action on species conservation. When critical habitat is identified, either in a recovery strategy or an action plan, there may be future regulatory implications, depending on where the critical habitat is identified. SARA requires that critical habitat identified within a national park named and described in Schedule 1 to the Canada National Parks Act, the Rouge National Urban Park established by the Rouge National Urban Park Act, a marine protected area under the Oceans Act, a migratory bird sanctuary under the Migratory Birds Convention Act, 1994 or a national wildlife area under the Canada Wildlife Act be described in the Canada Gazette, after which prohibitions against its destruction will apply. For critical habitat located on other federal lands, the competent minister must either make a statement on existing legal protection or make an order so that the prohibition against destruction of critical habitat applies. For any part of critical habitat located on non-federal lands, if the competent minister forms the opinion that any portion of critical habitat is not protected by provisions in or measures under SARA or other Acts of Parliament, or the laws of the province or territory, SARA requires that the Minister recommend that the Governor in Council make an order to prohibit destruction of critical habitat. The discretion to protect critical habitat on non-federal lands that is not otherwise protected rests with the Governor in Council.
Additions and Modifications to the Adopted Document
The following sections have been included to address specific requirements of the federal Species at Risk Act (SARA) that are not addressed in the Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia (Part 2 of this document, referred to henceforth as “the provincial recovery plan”) and to provide updated or additional information. In some cases, these sections may also include updated information or modifications to the provincial recovery plan for adoption by Environment and Climate Change Canada.
Under SARA, there are specific requirements and processes set out regarding the protection of critical habitat. Therefore, statements in the provincial recovery plan referring to protection of survival/recovery habitat may not directly correspond to federal requirements. Recovery measures dealing with the protection of habitat are adopted; however, whether these measures will result in protection of critical habitat under SARA will be assessed following publication of the final federal recovery strategy.
Kristiina Ovaska, Lennart Sopuck, and Christian Engelstoft of Biolinx Environmental Research Inc. drafted and/or contributed data/expertise to a preliminary version of this document.
1. Population and Distribution
This section replaces the information summary for known records of the Blue-grey Taildropper in British Columbia (Table 1 in the provincial recovery plan).
The updated information summary below (Table 1) describes the distribution and abundance of recorded populationsFootnote 1 in Canada. Since publication of the provincial recovery plan, two new populations have been identified. In West Saanich one individual was observed in 2014 (Ovaska and Sopuck 2014b) west of population #10 (Observatory Hill) and at Mt. Tzouhalem (Chase Woods), two individuals were observed in 2014 (Ovaska and Sopuck 2014a). The Chase Woods location, which is at the base of Mt. Tzouhalem near Duncan, is 25 km north of the nearest previously known population. The Prior Lake population (#12) was included in the Thetis Lake occurrence (#9) in the provincial recovery plan but is separated by >1 km and is thus treated as a separate population. All population numbers in this section align with those provided in Table 1 of the provincial recovery plan, aside from the additional populations described.
|Population||Population Name||Last Observation|
|2||Durrance Lake (Mount Work/Cole Hill)||2014|
|3||Galloping Goose (Sooke River)||2004|
|6||Mill Hill - Colwood||2009|
|12Note a of Table 1||Prior Lake||2011|
|13Note b of Table 1||Mt. Tzouhalem (Chase Woods)||2014|
|14Note b of Table 1||West Saanich||2014|
Notes of Table 1
- Note a of Table 1
Prior Lake was included in the Thetis Lake occurrence (#9) in the provincial recovery plan but is separated by >1 km and is thus treated as a separate population
- Note b of Table 1
New occurrence since provincial recovery plan
2. Critical Habitat
2.1 Identification of the Species’ Critical Habitat
This section replaces section 7.1 “Description of Survival/Recovery Habitat” in the provincial recovery plan.
Section 41 (1)(c) of SARA requires that recovery strategies include an identification of the species’ critical habitat, to the extent possible, as well as examples of activities that are likely to result in its destruction. More precise boundaries may be mapped, and additional critical habitat may be added in the future if additional information supports the inclusion of areas beyond those currently identified. A primary consideration in the identification of critical habitat is the amount, quality, and locations of habitat needed to achieve the population and distribution objectives.
It is recognized that the critical habitat identified below is insufficient to achieve the population and distribution objectives for the Blue-grey Taildropper. All known (and newly recorded) populations, and the habitat that supports them, are deemed necessary for the survival of the species. Detailed location information for some known populations is not available to Environment and Climate Change Canada (Population # 11 & 14).
Environment and Climate Change Canada will work with the applicable organizations and/or parties to complete the identification of critical habitat on those lands. The schedule of studies (Section 3.2) outlines the activities required to identify additional critical habitat necessary to support these objectives.
Geospatial location of areas containing critical habitat
Critical habitat for the Blue-grey Taildropper is identified at 12 locations in British Columbia, Canada:
Population 1. Devonian (Figure 1)
Population 2. Durrance Lake (Mount Work/Cole Hill) (Figure 6)
Population 3. Galloping Goose (Sooke River) (Figure 2)
Population 4. Logan (Figure 4)
Population 5. Matheson Lake (Figure 1)
Population 6. Mill Hill – Colwood (Figure 4)
Population 7. Rocky Point (Figure 1)
Population 8. Sooke Hills (Figure 3)
Population 9. Thetis Lake (Figure 4)
Population 10. Observatory Hill (Figure 5)
Population 12. Prior Lake (Figure 4)
Population 13. Mt. Tzouhalem (Chase Woods) (Figure 7)
Critical habitat for Blue-grey Taildropper in Canada is identified within two zones:
1. Occupied zone:
- occurrences for which detailed location information is available to Environment and Climate Change Canada, surrounded by an area with a 25 m radial distance to account for limited seasonal movement and error associated with GPS mapping.
2. Zone of influence:
- an additional area with a 240 m radial distance delineated around the occupied zone to maintain a moist ‘interior forest’ microclimate (i.e., cooler temperatures and higher moisture levels) where the slugs occur. The 240 m radial area was selected based on edge effects studies from coastal forests (Voller 1998 and Chen et al. 1995). Voller (1998) found that the microclimatic influence of the forest edge (i.e., lower humidity) penetrates 200 m or more into mature coastal forests, meaning that a forested buffer of >200 m must be present in order to maintain unmodified ‘interior’ conditions within the centre of a patch. Chen et al (1995) showed a similar pattern: that humidity is affected up to 240 m from the forest edge. The slightly larger 240 m distance was selected as a precautionary measure.
Biophysical attributes of critical habitat
The Blue-grey Taildropper requires habitats with features that provide/maintain moist conditions and provide cover, food (fungi and understorey plants), and egg-laying/rearing substrate (Blue-grey Taildropper Recovery Team 2012; Ovaska and Sopuck 2010, 2012, and 2014b). Specific biophysical attributes are summarized as follows.
Within the occupied zones (Figures 1-7), critical habitat is identified wherever any of these biophysical attributes occur:
- Mature (>50-year-old) mixed-wood overstory with semi-open canopy (20-70% closure; Ovaska and Sopuck 2010) that may contain Douglas-fir (Pseudotsuga menziesii), Grand Fir (Abies grandis), and/or Western Redcedar (Thuja plicata) along with a deciduous component of Arbutus (Arbutus menziesii), Garry Oak (Quercus garryana), Bigleaf Maple (Acer macrophyllum) and/or Trembling Aspen (Populus tremuloides), to maintain moisture, provide mycorrhizal fungi (for food), and contribute coarse woody debris and litter for localized moisture, cover, and egg-laying/rearing substrate;
- understory of shrubs (especially Oceanspray [Holodiscus discolor], Salal [Gaultheria shallon], Dull Oregon Grape [Mahonia nervosa], rose [Rosa spp.], and Trailing Blackberry [Rubus ursinus]), and grasses/herbs (often including Sword Ferns [Polystichum munitum]), to provide cover and maintain moisture;
- depressions, swales, seepage areas, or ephemeral wet areas, to provide moisture;
- well-developed litter/duff layer and/or coarse woody debris (at any stage of decay), to provide localized moisture, cover, and substrate for egg-laying/rearing and fungi growth (for food).
Within the zone of influence areas (Figures 1-7), critical habitat is identified wherever the following biophysical attribute occurs:
- Mature (>50-year-old) mixed-wood overstory with semi-open canopy (20-70% closure) that may contain Douglas-fir (Pseudotsuga menziesii), Grand-Fir (Abies grandis), and/or Western Redcedar (Thuja plicata) along with a deciduous component of Arbutus (Arbutus menziesii), Garry Oak (Quercus garryana), Bigleaf Maple (Acer macrophyllum) and/or Trembling Aspen (Populus tremuloides), to maintain moisture.
Spatial Information on critical habitat
The areas containing critical habitat for Blue-grey Taildropper are presented in Figures 1-7. Critical habitat for Blue-grey Taildropper in Canada occurs within the shaded yellow polygons shown on each map, wherever the biophysical attributes described in this section occur. Unsuitable habitats such as dry meadows, open water and anthropogenic features (e.g., buildings and roads) do not possess the attributes required by the Blue-grey Taildropper and therefore are not identified as critical habitat. The 1 km x 1 km UTM grid overlay shown on these figures is a standardized national grid system that highlights the general geographic area containing critical habitat, for land use planning and/or environmental assessment purposes.
2.2 Schedule of Studies to Identify Critical Habitat
This section replaces section 7.2, “Studies Needed to Describe Survival/Recovery Habitat”, in the provincial recovery plan. The following schedule of studies will enable the identification of critical habitat for the Blue-grey Taildropper at additional locations in British Columbia.
|Description of activity||Rationale||Timeline|
|Obtain data sharing agreements with appropriate individuals permitting access to known, but not yet available, detailed location information (populations #11 & 14).||This will allow for the identification of critical habitat to support all known populations.||2010-2020|
2.3 Activities Likely to Result in Destruction of Critical Habitat
Understanding what constitutes destruction of critical habitat is necessary for the protection and management of critical habitat. Destruction is determined on a case by case basis. Destruction would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species. Destruction may result from a single or multiple activities at one point in time or from the cumulative effects of one or more activities over time.
Activities described in Table 3 include those likely to cause destruction of critical habitat within the ‘occupied zone’ for the species. Table 4 includes activites likely to cause destruction of critical habitat within the ‘zone of influence’. Destructive activities are not limited to those listed.
|Description of Activity||Description of effect||Details of effect|
|Activities involving complete removal/loss of critical habitat (e.g., construction of new or expansion of existing residential/industrial/recreational developments or transportation).||Results in loss of all critical biophysical attributes.||Related IUCN Threat #1.1, 1.2, 1.3, 4.1.|
|Tree removal activities that result in <20% canopy cover (e.g., logging).||Significant removal of the overstorey can eliminate/alter the moist microclimate and reduce the presence of mycorrhizal fungi (food) and the supply of coarse woody debris and litter (cover and egg-laying/rearing substrate).||Related IUCN Threat #5.3. Limited/small-scale removal of trees (not accompanied by significant disturbance of the understorey/forest floor) can be beneficial for Blue-grey Taildropper if it results in old-growth-like canopy conditions.|
|Activities that alter the understory and forest floor substrate (e.g., brush clearing, burning, woody debris removal, addition of bark mulch or other substrate [for trail construction], and herbicide application).||Removal of understorey plants and coarse woody debris or the addition of non-natural substrates can eliminate/alter the moist microclimate and reduce the availability of critical cover, food (plants and fungi), and egg-laying/rearing substrate.||Related IUCN Threat #7.1. Removal of invasive plants is recommended but should be carried out with care to minimize soil disturbance and avoid compaction of the forest floor by trampling. The information available at this time is insufficient to develop a threshold for this activity.|
|Intensive recreational use (e.g., camping, concentrated hiker traffic, off-road operation of motorized or non-motorized vehicles such as mountain bikes, ATVs and dirtbikes).||Intensive recreational use can lead to soil compaction, which could alter/eliminate moist microfeatures such as seeps and swales and reduce the growth of fungi (food). Recreational vehicles can also introduce invasive plant species by spreading seeds from nearby areas; some invasive plant species can grow into dense monocultures that reduce/alter soil moisture.||Related IUCN Threat #6.1. Recreational trails are present in the vicinity of all Blue-grey Taildropper populations. The information available at this time is insufficient to develop a threshold for this activity.|
|Intentional planting or introduction of invasive plants (e.g., dumping of garden waste or other plant materials into natural habitats, hydroseeding with non-native species).||Some invasive plant species (e.g., Scotch Broom [Cytisus scoparius] and Spurge-laurel [Daphne laureola]) can grow into dense monocultures that reduce/alter soil moisture.||Related IUCN Threat #8.1. Scotch Broom has been recorded at populations #7 & 9. Spurge-laurel has been recorded at population # 9.|
|Description of Activity||Description of effect||Details of effect|
|Tree removal activities that result in <20% canopy cover (e.g., logging, construction of new or expansion of existing residential/industrial/recreational developments or transportation).||Significant removal of the overstorey within the zone of influence can eliminate/alter the moist microclimate within the occupied zone.||Related IUCN Threat #1.1, 1.2, 1.3, 4.1, and 5.3. Limited/small-scale removal of trees can be beneficial for Blue-grey Taildropper if it results in old-growth-like canopy conditions.|
3. Measuring Progress
This section replaces the “Measuring Progress” section in the provincial recovery plan.
The performance indicators presented below provide a way to define and measure progress towards achieving the population and distribution objective set out in the provincial recovery plan.
- Blue-grey Taildropper populations are stable or increasing in abundance.
In addition to this performance indicator, the performance measures set out in the provincial recovery plan (section 8) will provide pertinent information to assess interim progress towards achieving the ultimate population and distribution goal.
4. Statement on Action Plans
This section replaces the “Statement on Action Plans” section in the provincial recovery plan.
One or more action plans for the Blue-grey Taildropper will be posted on the Species at Risk Public Registry by 2021.
5. Effects on the Environment and Other Species
This section replaces the “Effects on Other Species” section in the provincial recovery plan.
A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s (FSDS) goals and targets.
Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the strategy itself, but are also summarized below in this statement.
Negative impacts to other species are not anticipated and are unlikely. Habitat protection and management that promote conservation of the Blue-grey Taildropper are expected to benefit other organisms occupying similar woodland habitats, as well as endangered Garry Oak ecosystems.
The following species at risk are known to or might co-occur with this species:
Terrestrial gastropods (COSEWIC status):
- Warty Jumping-slug (Hemphillia glandulosa) (Special Concern 2003), which is known from similar habitats on southern Vancouver Island and co-occurs with the Blue-grey Taildropper at least at one location.
- Threaded Vertigo (Nearctula sp. 1) (Special Concern 2010), which is known from similar habitats on southern Vancouver Island and co-occurs with the Blue-grey Taildropper at least at two locations.
- Puget Oregonian Snail (Cryptomastix devia) (Extirpated 2002). The two species overlap in their habitat use in the United States (Pilsbry 1940), but no recent Canadian records exist.
Plants (COSEWIC status):
- Scouler’s Corydalis (Corydalis scouleri) (Threatened 2001)
- Phantom Orchid (Cephalanthera austiniae) (Threatened 2000)
- Coastal Wood Fern (Dryopteris arguta) (Special Concern 2001)
- Streambank Lupine (Lupinus rivularis) (Endangered 2002)
Refer to section 9 (Effects on Other Species) of the provincial recovery plan for a full list of species that may benefit from recovery efforts for the Blue-grey Taildropper Slug. Recovery planning activities for Blue-grey Taildropper Slug will be implemented with consideration for all co-occurring species at risk, such that there are no negative impacts to these species or their habitats
Blue-grey Taildropper Recovery Team. 2012. Recovery Plan for Blue-grey Taildropper (Prophysaon coeruleum) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 36 pp.
Chen, J., J.F. Franklin, and T.A. Spies. 1995. Growing-season Microclimate Gradients from Clearcut Edges into Old-Growth Douglas-Fir Forests. Ecological Applications 5:74-86.
Cordeiro, J. 2004. Population/occurrence delineation – terrestrial snails. Section in NatureServe. 2013. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available: (accessed February 2013).
COSEWIC 2006. COSEWIC assessment and status report on the Blue-grey Taildropper slug Prophysaon coeruleum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 27 pp. <www.sararegistry.gc.ca/status/status_e.cfm>
NatureServe. 2015. NatureServe Explorer: an online encyclopedia of life [web application]. Version 7.1. Arlington, V.A. [Accessed May, 2015].
Ovaska, K. and L. Sopuck. 2010. Surveys for the Blue-grey Taildropper and other gastropods at risk with focus on Capital Regional District Parks, fall 2010. Report prepared for Habitat Acquisition Trust, Victoria, BC. 30 pp.
Ovaska, K. and L. Sopuck. 2012. Surveys for the Blue-grey Taildropper and other gastropods at risk with focus on Capital Regional District Parks, fall 2011. Report prepared for Habitat Acquisition Trust, Victoria, BC.30 pp.
Ovaska, K. and L. Sopuck. 2014a. Surveys for Blue-grey Taildropper and other gastropods at risk on southern Vancouver Island in 2014. Report prepared for Habitat Acquisition Trust, Victoria, BC. 28pp. + appendices.
Ovaska, K. and L. Sopuck. 2014b. Surveys and Stewardship for Blue-grey Taildropper on southern Vancouver Island, autumn 2013. Report prepared for Habitat Acquisition Trust, Victoria, BC. 23pp. + appendices.
Pilsbry, H.A. 1940. Land mollusca of North America (north of Mexico). Academy of Natural Sciences of Philadelphia, Monograph 3, 1(2):575–994, i–ix.
Sopuck, L. and K. Ovaska. 2012. Surveys for the Blue-grey Taildropper and other gastropods at risk in the Capital Regional District, autumn 2011. Report prepared for Habitat Acquisition Trust, Victoria, BC. 30 pp.
Voller , J. 1998. Biodiversity and Interior Habitats: The need to minimize edge effects. Part 6 of 7. Extension Note 21. BC Ministry of Forests. 8 pp.
- Footnote 1
“Populations” are characterized as being separated by >1 km (Cordeiro 2004 in NatureServe 2013).
- Date Modified: