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Recovery Strategy for Dun Skipper (Euphyes vestris vestris) in Canada - 2017 [Proposed]

Part 2 - Recovery Plan for Dun Skipper (Euphyes vestris) in British Columbia, prepared by the British Columbia Ministry of Environment

Recovery Plan for Dun Skipper (Euphyes vestris) in British Columbia

Photo of Dun Skipper
Photo: © Denis Knopp

Prepared by B.C. Ministry of Environment
December 2013


Document Information

About the British Columbia Recovery Strategy Series

This series presents the recovery strategies that are prepared as advice to the Province of British Columbia on the general strategic approach required to recover species at risk. Recovery strategies are prepared in accordance with the priorities and management actions assigned under the British Columbia Conservation Framework. The Province prepares recovery strategies to ensure coordinated conservation actions and meet its commitments to recover species at risk under the Accord for the Protection of Species at Risk in Canada, and the Canada - British Columbia Agreement on Species at Risk.

What is recovery?

Species at risk recovery is the process by which the decline of an endangered, threatened, or extirpated species is arrested or reversed, and threats are removed or reduced to improve the likelihood of a species' persistence in the wild.

What is a provincial recovery strategy?

Recovery documents summarize the best available scientific and traditional information of a species or ecosystem to identify goals, objectives, and strategic approaches that provide a coordinated direction for recovery. These documents outline what is and what is not known about a species or ecosystem, identify threats to the species or ecosystem, and explain what should be done to mitigate those threats, as well as provide information on habitat needed for survival and recovery of the species. This information may be summarized in a recovery strategy followed by one or more action plans. The purpose of an action plan is to offer more detailed information to guide implementation of the recovery of a species or ecosystem. When sufficient information to guide implementation can be included from the onset, all of the information is presented together in a recovery plan.

Information provided in provincial recovery documents may be adopted by Environment Canada for inclusion in federal recovery documents that the federal agencies prepare to meet their commitments to recover species at risk under the Species at Risk Act.

What's next?

The Province of British Columbia accepts the information in these documents as advice to inform implementation of recovery measures, including decisions regarding measures to protect habitat for the species.

Success in the recovery of a species depends on the commitment and cooperation of many different constituencies that may be involved in implementing the directions set out in this document. All British Columbians are encouraged to participate in these efforts.

For more information

To learn more about species at risk recovery in British Columbia, please visit the Ministry of Environment Recovery Planning webpage

Recommended Citation

B.C. Ministry of Environment. 2013. Recovery plan for Dun Skipper (Euphyes vestris) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 36 pp.

Cover illustration/photograph

Denis Knopp, BC's Wild Heritage Consultants, Sardis, BC

Additional copies

Additional copies can be downloaded from the B.C. Ministry of Environment Recovery Planning webpage

Publication information

Library and Archives Canada Cataloguing in Publication

Recovery plan for dun skipper (Euphyes vestris) in British Columbia [electronic resource] / prepared by the B.C. Ministry of Environment.

(British Columbia recovery strategy series)
Electronic monograph in PDF format.
Includes bibliographical references.

1. Hesperiidae--British Columbia. 2. Rare butterflies--British Columbia. 3. Wildlife recovery--British Columbia. I. British Columbia. Ministry of Environment II. Series: British Columbia recovery strategy series

Disclaimer

This recovery plan has been prepared by the British Columbia (B.C.) Ministry of Environment with input from the Dun Skipper Working Group of the BC Invertebrates Recovery Team, as advice to the responsible jurisdictions and organizations that may be involved in recovering the species. The B.C. Ministry of Environment has received this advice as part of fulfilling its commitments under the Accord for the Protection of Species at Risk in Canada, and the Canada–British Columbia Agreement on Species at Risk.

This document identifies the recovery strategies that are deemed necessary, based on the best available scientific and traditional information, to recover Dun Skipper populations in British Columbia. Recovery actions to achieve the goals and objectives identified herein are subject to the priorities and budgetary constraints of participatory agencies and organizations. These goals, objectives, and recovery approaches may be modified in the future to accommodate new objectives and findings.

The responsible jurisdictions and all members of the working group have had an opportunity to review this document. However, this document does not necessarily represent the official positions of the agencies or the personal views of all individuals on the working group.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that may be involved in implementing the directions set out in this plan. The B.C. Ministry of Environment encourages all British Columbians to participate in the recovery of Dun Skipper.

Acknowledgements

Jennifer Heron (B.C. Ministry of Environment [MoE]) wrote the recovery plan with subsequent review and input from some members of the BC Invertebrates Recovery Team. Leah Westereng (B.C. MoE) completed editorial revisions and policy guidance (B.C. Ministry of Environment 2010a). Both the recovery plan and updated Committee on the Status of Endangered Wildlife in Canada (COSEWIC) status report were written simultaneously, and much of the text and information contained within are in both documents.

Thank you to private landowners on Denman Island, Hornby Island, Courtenay, Comox, southeastern Vancouver Island, Metro Vancouver, Fraser Valley Regional District, and other owners that also granted access to their properties for surveys.

The following people contributed information to this document: Denis Knopp and Lee Larkin (BC's Wild Heritage Consultants); Laura Parkinson (B.C. Conservation Foundation); Nick Page (Raincoast Applied Ecology); Suzie Lavallee (University of B.C., Faculty of Forestry); Michelle Connolly (Private Entomologist); Patrick Lilley (Echo Blue Consulting); Crispin Guppy (Private Entomologist); Darren Copley (Royal BC Museum); Jeremy Tatum; Steve Ansell; Derrick Marvin; James Miskelly; David Threatful; Janice Jarvis, Alison Eveley, and Markus Merkens (Metro Vancouver); Marilyn Fuchs (Capital Regional District); Bill Woodhouse, Drew Chapman, and Mike Rody (BC Parks); and the B.C. Conservation Data Centre (Leah Ramsay, Lea Gelling, and Katrina Stipec).

The Dun Skipper Working Group thanks the following people:

  • Claudia Copley (Royal BC Museum) and Karen Needham (University of B.C., Beaty Biodiversity Museum, Spencer Entomological Collection) for assistance with museum records.
  • Ann Potter (U.S. Fish and Wildlife Service), Ted Thomas (Washington Department of Fish and Wildlife), and Robert Pyle for information about Dun Skipper in Washington State.
  • Kathryn Martell, Shyanne Smith, and Chris Junck (Garry Oak Ecosystems Recovery Team). Rob Knight (B.C. MoE, retired) for facilitating access to the orthophotos used for habitat identification and mapping.
  • local conservation organizations for butterfly surveys and private landowner contact (Robin Annschild, Tyla Crowe, Michael Dunn, Tony Law, Francis McLean, J. Thornton, and A. Fyson).

The following MoE staff completed a review on an earlier draft: Patrick Daigle, Jenny Feick, Brenda Costanzo, Ted Lea, and Jeff Brown.

Dun Skipper working group

Jennifer Heron (Chair), B.C. Ministry of Environment, Vancouver

Trudy Chatwin, B.C. Ministry of Environment, Nanaimo (Region 1)

Megan Harrison, Canadian Wildlife Service, Environment Canada, Delta

Chris Junck, Garry Oak Ecosystems Recovery Team, Victoria

Denis Knopp, BC's Wild Heritage, Sardis

Suzie L. Lavallee, University of British Columbia, Vancouver

Patrick Lilley, Echo Blue Consulting, North Vancouver

Erica McClaren, B.C. Parks and Protected Areas, Black Creek

Kristina Robbins, B.C. Ministry of Forests, Lands and Natural Resource Operations Region 2, Surrey

Malissa Smith, B.C. Ministry of Forests, Lands and Natural Resource Operations Region 2, Surrey

Andrea Tanaka, Canadian Wildlife Service, Environment Canada, Delta

Executive summary

Dun Skipper (Euphyes vestris) is a small butterfly (wingspan 23–32 mm) with uniform chocolate-brown wings with a purplish hue and tan fringes on the outer margins. Adults sit with their hindwings laid flat and their forewings held upright. The head and thorax of adults (both sexes) are yellowish-orange. Eggs are pale green, crescent-shaped, globular, and smooth when first laid, but prior to hatching the top of the egg changes to a reddish colour. Larvae have a shiny, pale green body with many fine and wavy silvery lines. Pupae are various shades of yellow, brown, and light green, with a blunt, ridged edge at one end.

Dun Skipper was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2001. The reasons for this assessment were that the western population of Dun Skipper (vestris subspecies) occurs in a restricted area. It has all but disappeared from Vancouver Island and its continued survival on the island is doubtful. Although the mainland population is limited by the availability of suitable habitat, populations at some locations are relatively secure. The butterfly is listed as Threatened in Canada on Schedule 1 of the Species at Risk Act (SARA). In British Columbia, Dun Skipper is ranked S3 (special concern, vulnerable to extirpation or extinction) by the Conservation Data Centre and is on the provincial Blue list. The B.C. Conservation Framework ranks Dun Skipper as a priority 2 under goal 2 (prevent species and ecosystems from becoming at risk). Recovery is considered to be biologically and technically feasible.

Dun Skipper has been observed in a variety of habitats: adjacent to or within open forest comprised of Douglas-fir with lowland forest components below cliffs and hillsides; close to open, sparsely vegetated cliffs; edges of sedge-dominated wetlands and wet grasslands; and bog habitats with moisture for host plant longevity. Towards the interior of the Fraser Valley, and as habitats became drier (e.g., Boston Bar, Lillooet to Pemberton), Dun Skipper has been observed on gently sloping hillsides, generally within 1 km of cliff habitat. In the most xeric sites (e.g., Lillooet), the sites were sheltered from wind and associated with moister Douglas-fir habitat. The butterfly has been recorded in disturbed sites including roadsides, railway right-of-ways, ditches, and power line right-of-ways; areas with spring floods, natural hot springs or seeps, and stream banks; and habitats that appear dry but where spring floods likely occur and moist conditions sustain populations of potential host plants. The primary correlation between these habitat types is the high wet and moist ground throughout the spring/summer, thus preventing premature host plant senescence. Dun Skipper is also recorded from Garry oak and associated ecosystems on southeastern Vancouver Island. Dun Skipper host plants are not known but are thought to be in the sedge family (Carex spp.) including Carex heliophila (no English name) and the grass family (Poa spp).

Threats to the Dun Skipper include (1) habitat loss, degradation, and fragmentation from land conversion and infilling of the open wet habitat and plant communities throughout the Lower Mainland and southeastern Vancouver Island; (2) natural forest succession; (3) pesticide application to control European Gypsy Moth (Lymantria dispar); and (4) climate change, primarily through increases in summer drought, potentially resulting in desynchronised larval and host plant phenology.

The population and distribution goal is to maintain current populations for Dun Skipper throughout the species natural range and distribution in British Columbia.

The following are the recovery objectives:

  1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.
  2. To secure protectionFootnote 8 for Dun Skipper habitats within the species' range.
  3. To assess and reduce threats to all known Dun Skipper sites in B.C.
  4. To address knowledge gaps (e.g., population size, host plant requirements) that will enable quantitative population and distribution objectives to be set.

Recovery feasibility summary

The recovery of Dun Skipper in B.C. is considered technically and biologically feasible based on the criteria outlined by the Government of Canada (2009):

1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.
Yes. Dun Skipper individuals capable of reproducing continue to be recorded from some of the known sites; however, the population viability and longevity are unknown. Approximately 18 locations (based on land ownership) for Dun Skipper are known from recent surveys (2000–2010) within the Canadian (B.C.) range. It is unknown if populations within larger habitat patches may be able to persist with little or no management of threats and whether these individuals can repopulate habitats quickly (e.g., within 25 years, 50 years).
2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
Yes. Dun Skipper has been observed in a variety of open habitat types and potential host plants are widespread within the species' B.C. range. There is abundant habitat similar to where Dun Skipper has recently been observed (2000–2010). Restoration of habitats that have already been modified by urban or agricultural practices may be possible in some cases.
3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
Yes. Numerous Dun Skipper sites and corresponding habitats are within provincial Crown and municipal government lands (see Table 1) and lands managers are aware of the butterfly and its habitat needs. Stewardship activities through the South Coast Conservation Program (SOSCP 2012) and Garry Oak Ecosystems Recovery Team (GOERT 2013) aim to bring awareness to private landowners and land users about Dun Skipper and other butterfly species at risk. The provincial Gypsy Moth Committee is aware of Dun Skipper and aims to avoid known locations and habitat in the event of aerial and ground spray programs to control gypsy moth. The B.C. range of Dun Skipper coincides with a densely human populated, fertile part of B.C. and threats to unsurveyed potential habitat will continue. Threats to the species habitat (e.g., urban and rural private land development, introduced species changing natural plant communities) are unavoidable although mitigation efforts will aid in protecting the species.
4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.
Yes. Techniques used to recover Dun Skipper are similar to the recovery planning applied to species with similar threats and habitat requirements. Recovery techniques include habitat protection, removal of location-specific threats (such as introduced species), and working with land managers and landowners to develop site-specific best management practices guidelines and shared stewardship opportunities.

1 COSEWICi species assessment information

Assessment summary :
May 2013
Common name (population) :ii
Skipper vestris subspecies, Dun
Scientific name:ii
Euphyes vestries vestris
COSEWIC status:
Threatened
Reason for designation:
This species has a small population found in a restricted range in southwestern British Columbia, where it occurs in moist, open habitats, including meadows, wetlands, and disturbed sites. Meadows and wetlands are declining in area and quality owing to natural succession, residential and commercial development, and invasive plants. Disturbed sites are inherently ephemeral and rapidly becoming unsuitable due to native and invasive plant succession. This is a rare species, and despite significant search effort over the last decade, few new sites have been located.
Canadian occurrence:
B.C.
Status history:
Designated Threatened in November 2000. Status re-examined and confirmed in May 2013

i Committee on the Status of Endangered Wildlife in Canada.

ii Common and scientific names reported in this recovery plan follow the naming conventions of the B.C. Conservation Data Centre, which may be different from names reported by COSEWIC

2 Species status information

Dun Skipper (Euphyes vestris)iii

Legal designation

Conservation statusvi

B.C. conservation frameworkviii

Goal 1: Contribute to global efforts for species and ecosystem conservation.
Priority:ix 4 (2009)
Goal 2: Prevent species and ecosystems from becoming at risk.
Priority: 2 (2009)
Goal 3: Maintain the diversity of native species and ecosystems.
Priority: 3 (2009)
CF action groups:
Inventory

iii Data source: B.C. Conservation Data Centre (2013) unless otherwise noted.

iv No = Not listed in one of the categories of wildlife that require special management attention to address the impacts of forest and range activities on Crown land under the Forest and Range Practices Act (FRPA; Province of British Columbia 2002) and/or the Oil and Gas Activities Act (OGAA; Province of British Columbia 2008).

v No = Listed as Endangered or Threatened under the Wildlife Act (Province of British Columbia 1982).

vi S = Subnational; N = National; G = Global; B = Breeding; X = presumed extirpated; H = possibly extirpated; 1 = critically imperiled; 2 = imperiled; 3 = special concern, vulnerable to extirpation or extinction; 4 = apparently secure; 5 = demonstrably widespread, abundant, and secure; NA = not applicable; NR = unranked; U = unrankable.

vii Data source: NatureServe (2012).

viii Data source: Ministry of Environment (2010b).

ix Six-level scale: Priority 1 (highest priority) through to Priority 6 (lowest priority).

3 Species information

3.1 Species Description

Taxonomy: There are 4 subspecies in North America. Two Dun Skipper subspecies occur in Canada: a western population (Euphyes vestris vestris) found only in B.C. and an eastern population (Euphyes vestris metacomet) found from Alberta east to Nova Scotia (Layberry et al. 1998; NatureServe 2012). Only Dun Skipper, vestris subspecies has been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). From this point forward Dun Skipper refers to "Dun Skipper, vestris subspecies" unless stated otherwise.

Adults: Dun Skipper is a small butterfly (wingspan 23–32 mm) with uniform chocolate brown-purplish wings and tan fringes at the outer wing margins (Figures 1 and 2). The sexes have differing markings on the wings. Males have a black stigma (scent scale) on the forewings and the area of attachment to the body is a darker brown than the outer wings. Females have small white cloudy spots on both the fore- and hindwing dorsal surfaces, and the hindwing ventral surfaces have a pale purplish crescent. Adults sit with their hindwings laid flat and their forewings held upright. The head and thorax of adults (both sexes) is yellowish-orange (Layberry et al. 1998; Guppy and Shepard 2001).

Figure 1. Dun Skipper 1 (Euphyes vestris) adults (male), taken July 1, 2009, adjacent to a gas pipeline right-of-way near Hope, B.C. Photograph by Denis Knopp.
Photo of Dun Skipper (see long description below)
Long description for Figure 1

Figure 1 shows a side angle shot of a male adult Dun Skipper resting on flowers near Hope, British Columbia.

Figure 2. Dun Skipper (Euphyes vestris) adults (male), taken July 7, 2010, adjacent to a gas pipeline right-of-way near Hope, B.C. Photograph by Denis Knopp.
Photo of Dun Skipper 2 (see long description below)
Long description for Figure 2

Figure 2 shows a bird's-eye-view shot of a male adult Dun Skipper resting on flowers near Hope, British Columbia.

Immature life stages: Dun Skipper eggs, larvae, or pupae have not been observed in B.C. and the following descriptions are based on other subspecies. Eggs are crescent-shaped, globular, and smooth and pale green when first laid (Heitzman 1965; Brown and McGuire 1983; Guppy and Shepard 2001). Before hatching eggs change to a reddish colour on top (Guppy and Shepard 2001; Pyle 2002). Larvae (14–36 mm long depending on their age) have a translucent pale green and shiny body with many fine and wavy silvery lines. A black to caramel-coloured stripe surrounds the head, and a lateral brown stripe and a small black spot is in front of the stripe (Layberry et al. 1998; Guppy and Shepard 2001). As larvae age, a darker green stripe appears laterally (Brown and McGuire 1983). The head is pale orange brown with dark stripes on the back. Larvae are known to form silken shelters made from rolled and curled host plant leaves (discussed below). Pupae are various shades of yellow, brown, and light green, with a blunt, ridged edge (eNature.com 2011).

Life history: Dun Skipper flight period is from mid-May to mid-August (Layberry et al. 1998; Guppy and Shepard 2001; B.C. Conservation Data Centre 2013) with one brood per year (Opler and Krizek 1984) and peak activity throughout June. During the flight period, males perch approximately 1 m from the ground and wait for receptive females (Opler et al., coordinators 1995). Females deposit eggs singly at the base, midway along, or under the leaf or stem of the host plant (Heitzman 1964; Guppy and Shepard 2001). Eggs hatch after approximately 7 days (Heitzman 1964).

As Dun Skipper larvae grow into the second larval instar (and later stages), they weave silk shelters from tied and rolled leaves. Larval refuge sites are found near the base of the host plant and may occur on the same host plant upon which the egg was laid, or an adjacent host plant. A larval refuge is a tubular structure constructed of 2–4 leaves of sedges or grasses (Brown and McGuire 1983). The larva joins the leaves of the plant together with silk to create a chamber for its development and protection (Heitzman 1964; Brown 1982; Brown and McGuire 1983). Larvae occupy refuge structures during development and, when not feeding, likely remain within these structures. Larvae abandon the refuge structure and construct a new one on the same or adjacent sedge or grass plants when the nearby food supplies are exhausted (Brown and McGuire 1983). Older larvae use one or more refuge structures for 24–36 days between late May and late August (Heitzman 1964; Brown and McGuire 1983). Pupation occurs within the larval silken refuge structures at the base of, presumably, the host plants. No larval structures or pupae have been observed in B.C.

3.2 Populations and distribution

3.2.1 Global distribution

The North American range extent of Dun Skipper (all subspecies) is in question due to lack of distribution records and taxonomic uncertainty (Figure 3).

Dun Skipper (Euphyes vestris vestris) is at the northernmost extent of its range in southwestern B.C. and southeastern Vancouver Island. The subspecies ranges southward into the Cascade Mountains in Washington State (Figure 3; NatureServe 2012). Although there is some evidence the butterfly may occur south to northern California, there are a lack of distribution records.

Figure 3. Dun Skipper distribution in North America. Two subspecies occur in Canada (Euphyes vestris vestris and E. vestris metacomet). The other 2 subspecies (E. vestris kiowah and E. vestris harbisoni) range in the United States and Mexico.
Map of Dun Skipper in North America (see long description below)
Long description for Figure 3

Figure 3 shows a distribution map for 4 different subspecies of Dun Skipper. Euphyes vestris vestris and E.v.metacomet range across Canada meanwhile E.v.kiowah and E.v.harbisoni range throughout the United States and Mexico.

B.C./Canadian distribution

Dun Skipper (Euphyes vestris) is restricted to B.C. within the coastal lowlands of the lower Fraser Valley, the southern Gulf Islands, and southeastern Vancouver Island (Figure 4). Within the lower Fraser Valley the species' northernmost location is Lillooet ranging south through Boston Bar, Yale, and Hope and into the Lower Mainland area at Burns Bog. West, the species has records in Pemberton and Powell River. On Vancouver Island, Dun Skipper ranges on the eastern side of the island from the Greater Victoria area north to Courtenay/Comox. Known Gulf Island localities include Salt Spring Island, Denman Island, and Hornby Island.

Figure 4. Dun Skipper distribution in British Columbia (B.C. Conservation Data Centre 2013).
Map of British Columbia (see long description below)
Long description for Figure 4

Figure 4 depicts the distribution population of Dun Skipper in British Columbia specifically outlining a likely biological population and landowner/site record. The majority of sites are located in the Victoria area and just northwest of Victoria. More sites are located just west and south west of Nanaimo as well as southeast and northeast of Courtenay. There is one location southeast of Victoria and one directly east from the previously mentioned location. A few more sites are noted ranging up the west side of the map.

Dun Skipper records in B.C. date from 1902 to 2012 (Table 1). Based on known records, the historic and present (combined) extent of occurrence is 32,597 km2 (25,924 km2 for the mainland and 6,673 km2 for Vancouver Island and Gulf Islands).

Dun Skipper extent of occurrence without historic sites (i.e., sites known from year 2000 to present) is similar, as most historic sites have been searched and/or are within the current extent of occurrence. The northeastern edges of the range within the lower Fraser Valley have been searched, and the range extended slightly during each survey (Knopp et al. 2007, 2009, 2010). Yet search effort in 2010 provided substantial null data suggesting the range limit is now well defined (Knopp et al. 2010). The northern range limit along the Sunshine Coast may extend approximately 50 km north of Powell River to Lund (Figure 4) although habitat north of Lund is difficult to access (i.e., no road access) and assess. When assessing habitat across Georgia Strait on Vancouver Island, there is a possibility Dun Skipper may occur at Campbell River (approximately 100 km north of Comox). Search effort indicates there is less suitable habitat north of Comox towards Campbell River (Page, Lilley, Heron et al. 2008; Page, Lilley, Miskelly et al. 2008; Page et al. 2009). However, inventory is likely to find additional sites within small patches of suitable habitat.

Table 1. Status and description of known Dun Skipper populations in B.C. as of 2012. All data in this table are from the B.C. Conservation Data Centre (2013). Location names are consistent with those in the BC Conservation Data Centre database.
PopulationhLocationPopulation statusiObservationsLand ownership
1Cowichan Station (Vancouver Island)Extirpated (1996)1996: One observationPrivate
2Mill Bay, Malahat Ridge (Vancouver Island)Extirpated (1996)1996: One seen at edge of clearcutPrivate
3Malahat, Colpman, and van Home Creeks; Spectacle Lake (Vancouver Island)Extant

2003 - Van Home Creek: 1 seen at intersection of road and railway

1994 - Colpman Creek: 1 seen at edge of clearcut; low bush and sparse grass

1963 - Spectacle Lake: 1 collected

1956 - Spectacle Lake: 1 collected

Private;
Possibly B.C. Crown land (Spectacle Lake Provincial Park collection record vague)
4Mount Tzuhalem; Maple Bay (Vancouver Island)Extirpated (1994)1994: One seen in rough grass at edge of gravel road. Lots being developed along this road; this precise site may now be gone, species may still remain on Mount TzuhalemPrivate
5Cobble Hill (Vancouver Island)Extirpated (1995)1995: One observedPrivate
6Nanaimo River (Vancouver Island)Extant

2009–2011: Dun Skippers recorded

1995: Noneseen, "site levelled"

1988: One collected (adjacent to Nanaimo Lakes Road area)

Private (forest company)
7Port Alberni, northeast of (Vancouver Island)Extant2003: 10–20 observed over a 0.2-ha logged areaPrivate
8Mount Currie (Mainland)Extant2001: Dun Skippers observed on the lawn and flying into the tall grass in the adjacent lotPrivate
9Shawnigan Lake, west of (Vancouver Island)Extant2003: 7 seen on July 17; 2 seen on July 22; 1 seen on August 3. Observed at south side of Kinsol TrestlePrivate (hobby farms; forest company)
10Big Sicker Mountain; Little Sicker Mountain; Mount Prevost; Somenos Garry Oak Preserve (Vancouver Island)Extant2003: One Dun Skipper observed at Big Sicker Mountain. 1956 to 1978: a total of 11 were collected from Mount Prevost, Little Sicker Mountain, and Somenos Garry Oak Preserve all within about a 4-km radius of each otherPrivate
11Powell River (Sunshine Coast, mainland)Unknown; likely extantNo specific date. Suitable unchecked habitat present so may be extantUnknown
12Koksilah River (Vancouver Island)Extant2003: 1 butterfly seen in a clearcutPrivate
13Colquitz; Francis/King Park and Thetis Lake Park (Vancouver Island)Extirpated (1963)

Francis/King Park: 1962: 6 butterflies collected (Shepard 2000)

Thetis Lake Park: 3 butterflies collected in July of 1962 and 1963

Private (Capital Regional District)
14Wellington (Vancouver Island)Extirpated (1979)1951–1979: A total of 6 specimens were collectedPrivate
15Goldstream (Vancouver Island)Extirpated (1923)1902–1923: A total of 9 specimens collected in June/JulyB.C. Crown land (Goldstream Provincial Park)
16Boston Bar (lower Fraser Valley)Extant (2007)

2007: 1 male and 1 female observed at 2 different sites during 6 days of targeted surveying in July and August on B.C. Crown land

2002: 11 males and 2 females were collected along the highway, and 39 were collected along the same stretch and east of the highway

1949: collection of 3 male specimens There are at least 11 sites of collection. The locations range along about 25 km of the highway

Private;
First Nations;
B.C. Crown land
17Dog Mountain (lower Fraser Valley)Extant (2007)

2007: At least 13 individuals were observed in 3 visits.

2002: 2 individuals observed along a gas pipeline crossing along highway

1918: 1 male specimen collected from Hope (habitat and location unknown)

Private;
B.C. Crown land
18Denman Island (northern Gulf Islands)Extant (2007)2007: Two individuals observedPrivate conservation land (Denman Conservancy Association)j
19Salt Spring Island; southeast (southern Gulf Islands)Extant (2007)

2007: 1 male observed within 500 m of previous sightings

2003 and 2004: Seen each year on either side of the road

2008 and 2009: observed at Burgoyne Bay Provincial Park

Private;
B.C. Crown land (Burgoyne Bay Provincial Park)
20Burns Bog (Lower Mainland)Extant (2004)2004: 5 individuals observed; assume butterfly is throughout bog habitatPrivate - Local government (Metro Vancouver; City of Vancouver; Municipality of Delta);
Private
21Hornby Island (Northern Gulf Islands)Extant (2004)2004: 1 individual observedB.C. Crown land (provincial park); Private - conservation land owned by Denman Conservancy
22Morris Lake, west of (lower Fraser Valley)Extant (2007)2007: 1 male observed in weedy area at the junction of logging road and Hemlock Ski Hill RoadB.C. Crown land
23Soowahlie Indian Reserve 14 (lower Fraser Valley)Extant (2004)2004: One individual observed near old gravel pitFederal (Indian Reserve)
24Yale (lower Fraser Valley)Extant (2001)2001: 4 individuals observed just north of the Community of YalePrivate
25Lytton, south of (lower Fraser Valley)Extant (2007)

2007: 5 individuals at a highway pull off

2002: 1 individual at a roadside seep

B.C. Crown land (highway area);
Possibly some private land (depending on where habitat ends)

h Note populations may contain more than one site within a given location and span multiple landowners.

i Extant (record > 2001) or Extirpated (record < 2001 or habitat gone).

j Habitat extends into provincial park but no observations of Dun Skipper yet recorded in park as of 2012 (J. Heron, pers. comm., 2012).

3.3 Needs of the tall Bugbane

Recent surveys (2004–2010) have focused on collecting habitat and biological information, yet habitat descriptions remain vague primarily because the host plant in B.C. has not been confirmed. The historical habitat of Dun Skipper is also difficult to characterize, given the lack of information that accompanies museum collections at the Royal B.C. Museum (C. Copley, pers. comm., 2012), the University of British Columbia Beaty Biodiversity Museum, Spencer Entomological Collection (K. Needham, pers. comm., 2012); and the Canadian National Collection of Insects, Arachnids and Nematodes (Shepard 2000a, 2000b).

3.3.1 Habitat and biological needs

Dun Skipper habitats are within the following biogeoclimatic zones: Coastal Douglas-fir (CDF), Coastal Western Hemlock (CWH) in the coastal areas, and Ponderosa Pine (PP) in the Boston Bar areas. This species has been observed in various habitat types, most of which are difficult to assign a specific ecosystem description. General habitat characteristics for Dun Skipper include open south to southwest slope exposures (< 15% slope); adjacent to or within open forest comprised of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) with lowland forest components below cliffs and hillsides comprised of Douglas-fir and open deciduous woods that include bigleaf maple (Acer macrophyllum Pursh); and close to open, sparsely vegetated cliffs (Knopp et al. 2007, 2009, 2010), edges of sedge-dominated wetlands and wet grasslands (Pyle 2002). Towards the interior of the Fraser Valley, and as habitats became drier (e.g., Boston Bar, Lillooet to Pemberton), Dun Skipper has been observed on gently sloping hillsides, generally within 1 km of cliff habitat. In the most xeric sites (e.g., Lillooet) the sites were sheltered from wind and associated with moister Douglas-fir habitat (Knopp et al. 2007, 2009, 2010).

Dun Skipper has also been recorded within bog habitats (e.g., Burns Bog), although the species is not considered a bog specialist. Bog conditions sustain moisture for host plant longevity, and warm dry conditions that seem to be favoured by the butterfly. The butterfly has been recorded in disturbed sites including roadsides, railway right-of-ways, ditches, and power line right-of-ways; areas with spring floods, natural hot springs or seeps (Guppy and Shepard 2001), and stream banks; and habitats that appear dry but where spring floods likely occur and moist conditions sustain populations of potential host plants (B.C. Conservation Data Centre 2013). The primary correlation between these habitat types is the high wet and moist ground throughout the spring/summer, thus preventing premature host plant senescence.

Dun Skipper has been recorded from Garry oak and associated ecosystems, yet the species is not considered a Garry oak obligate (Fuchs 2000). There are records of Dun Skipper in Garry oak habitats at Somenos Garry Oak Preserve (near Duncan), Francis/King Regional Park, Thetis Lake Regional Park, and Helliwell Provincial Park (Hornby Island) (Table 1; B.C. Conservation Data Centre 2013).

Moisture regime and successional stage: Dun Skipper habitat includes sites that have been disturbed (e.g., roadside ditches, clearcuts) with seasonally wet areas with abundant host plants, partially due to the early successional stage required by the likely grass and sedge family host plants. Undisturbed habitats with more apparent natural features include wet marshy habitats with common rush (Juncus effusus) plants.

Larval host plants: Dun Skipper host plants, in general, are in the sedge family (Carex spp.) including Carex heliophila Mackenzie (no English name) (Layberry et al. 1998; Pyle 2002) and the grass family (Poa spp.) (Brown and McGuire 1983). Dun Skipper (eastern population) larvae are known to feed upon non-native yellow nut-grass (Cyperus esculentus) (Heitzman 1965; Guppy and Shepard 2001), native San Diego sedge (Carex spissa Bailey) (Brown 1982; Layberry et al. 1998), native hairy sedge (Carex lacustris), and graceful sedge (Carex gracillima) (Layberry et al. 1998). Yet these plant species do not occur or are rare within B.C. (B.C. Conservation Data Centre 2013). Various species of grasses and sedges occur throughout the province within the known range of Dun Skipper (B.C. Conservation Data Centre 2013).

The matrix and dimensions of larval and nectar food plant habitat patch sizes, spatial boundaries, specific habitat characteristics, and features necessary to sustain Dun Skipper are poorly understood. Thus it may be the presence of the species' host plant(s) that determines its apparent random occupancy of a given habitat. Based on the distribution of Dun Skipper in B.C. (Figure 3), it is unlikely a single host-plant species is used. Dun Skipper is known to exhibit host plant specificity at any one locality but host polyphagy over the entire range (Shepard 2000a, 2000b).

Nectar plants: At sites within the lower Fraser Valley, Dun Skipper appears to favour nectar sources such as spreading dogbane (Apocynum androsaemifolium) (native plant) (Knopp et al. 2009, 2010) and alfalfa (Medicago sativa) (non-native) (Knopp et al. 2009). The butterfly is also known to use fireweed (Epilobium angustifolium L.) (native), lotus milk-vetch (Astragalus lotiflorus) (native), goldenrod (Euthamia spp. and Solidago spp.) (native), sweet William (Dianthus barbatus) (non-native), and various species of thistles (family Asteraceae; both native and non-native species) (Pyle 2002). On Denman Island, Dun Skipper was observed nectaring on oxeye daisy (Leucanthemum vulgare) (non-native) (Guppy et al. 2007).

3.3.2 Ecological role

Dun Skipper is not likely an essential pollinator of its larval host plant or adult nectar plants, nor is it known to have other crucial ecological roles such as food-web dynamics. Small mammals, invertebrate predators, and birds likely prey upon Dun Skipper.

3.3.3 Limiting factors

Host plant specificity and habitat specificity: Dun Skipper depends on larval host plants and without these plants the butterfly cannot complete its life cycle (see Section 3.3.1, Habitat and Biological Needs). The butterfly likely chooses nectar (adult) host plants opportunistically and preference may appear limited to the few plant species flowering during the flight period and not the specific biological preference by the butterfly. The main limiting factor for Dun Skipper is likely larval host plant availability and plant senescence (Shepard 2000a, 2000b). In early spring, host plants are just beginning to grow and thus host plant phenology likely influences larval growth and survival. As natural forest succession occurs these resources diminish.

Limited dispersal capability: Dun Skipper does not likely have high dispersal capabilities although it has not been documented how far the species will travel between host plant patches. Isolation due to dispersal limitations may lead to decreased genetic diversity within a population, greater genetic differences among locations, inbreeding depression, and no rescue effect.

Low population density: Dun Skipper appears to not form dense colonies or be present in high populations within suitable sites.

4 Threats

Threats are defined as the proximate activities or processes that have caused, are causing, or may cause in the future the destruction, degradation, and/or impairment of the entity being assessed (population, species, community, or ecosystem) in the area of interest (global, national, or subnational) (Salafsky et al. 2008). For purposes of threat assessment, only present and future threats are considered.Footnote 9 Threats presented here do not include biological features of the species or population such as inbreeding depression, small population size, and genetic isolation; or likelihood of regeneration or recolonization for ecosystems, which are considered limiting factors.Footnote 10

For the most part, threats are related to human activities, but they can be natural. The impact of human activity may be direct (e.g., destruction of habitat) or indirect (e.g., invasive species introduction). Effects of natural phenomena (e.g., fire, hurricane, flooding) may be especially important when the species or ecosystem is concentrated in one location or has few occurrences, which may be a result of human activity (Master et al. 2009). As such, natural phenomena are included in the definition of a threat, though should be applied cautiously. These stochastic events should only be considered a threat if a species or habitat is damaged from other threats and has lost its resilience, and is thus vulnerable to the disturbance (Salafsky et al. 2008) such that this type of event would have a disproportionately large effect on the population/ecosystem compared to the effect it would have had historically.

4.1 Threat assessment

The threat classification below is based on the IUCN-CMP (World Conservation Union–Conservation Measures Partnership) unified threats classification system and is consistent with methods used by the B.C. Conservation Data Centre and the B.C. Conservation Framework. For a detailed description of the threat classification system, see the CMP website (CMP 2010). Threats may be observed, inferred, or projected to occur in the near term. Threats are characterized here in terms of scope, severity, and timing. Threat "impact" is calculated from scope and severity. For information on how the values are assigned, see Master et al. (2009) and table footnotes for details. Threats for Dun Skipper were assessed for the entire province (Table 2).

Table 2. Threat classification table for Dun Skipper.
ThreatThreat categoriesImpactk
(calculated)
Scopel
(next 10 years)
Severitym
(10 years or 3 generations)
Timingn
1Residential & commercial developmentMediumRestricted (11–30%)Serious (31–70%)High – Moderate
1.1Housing & urban areasMediumRestricted (11–30%)Serious (31–70%)High (Continuing)
1.2Commercial & industrial areasLowSmall (1–10%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
1.3Tourism & recreation areasLowSmall (1–10%)Serious (31–70%)Moderate (Possibly in the short term, < 10 yrs)
2Agriculture & aquacultureLowSmall (1–10%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
2.1Annual & perennial non-timber cropsLowSmall (1–10%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
2.2Livestock farming & ranchingNot a Threat (in the assessed timeframe)Negligible (< 1%)UnknownInsignificant/Negligible (Past or no direct effect)
3Energy production & miningLowSmall (1–10%)Moderate (11–30%)Unknown
3.2Mining & quarryingLowSmall (1–10%)Moderate (11–30%)Unknown
4Transportation & service corridorsLowLarge (31–70%)Slight (1–10%)Moderate (Possibly in the short term, < 10 yrs)
4.1Roads & railroadsLowLarge (31–70%)Slight (1–10%)Moderate (Possibly in the short term, < 10 yrs)
4.2Utility & service linesLowSmall (1–10%)Slight (1–10%)Moderate (Possibly in the short term, < 10 yrs)
5Biological resource useNot a ThreatNegligible (< 1%)Neutral or Potential Benefit > 0%)High
5.3Logging & wood harvestingNot a ThreatNegligible (< 1%)Neutral or Potential Benefit > 0%)High
6Human intrusions & disturbanceNegligibleNegligible (< 1%)Negligible (< 1%)Insignificant/Negligible (Past or no direct effect)
6.1Recreational activitiesNegligibleNegligible (< 1%)Negligible (< 1%)Insignificant/Negligible (Past or no direct effect)
7Natural system modificationsLowPervasive (71–100%)Slight (1–10%)High (Continuing)
7.1Fire & fire suppressionLowPervasive (71–100%)Slight (1–10%)High (Continuing)
7.2Dams & water management/useNot a ThreatSmall (1–10%)Neutral or Potential BenefitHigh (Continuing)
7.3Other ecosystem modificationsLowSmall (1–10%)Slight (1–10%)High (Continuing)
8Invasive & other problematic species & genesLowRestricted (11–30%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
8.1Invasive non-native/alien speciesLowRestricted (11–30%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
8.2Problematic native speciesLowRestricted (11–30%)Moderate (11–30%)Moderate (Possibly in the short term, < 10 yrs)
9PollutionLowSmall (1–10%)Serious (31–70%)High (Continuing)
9.3Agricultural & forestry effluentsLowSmall (1–10%)Serious (31–70%)High (Continuing)
9.4Garbage & solid wasteNot a Threat (in the assessed timeframe)Small (1–10%)UnknownInsignificant/Negligible (Past or no direct effect)
10Geological eventsLowSmall (1–10%)ExtremeModerate (Possibly in the short term, < 10 yrs)
10.2Earthquakes/tsunamisLowSmall (1–10%)ExtremeModerate (Possibly in the short term, < 10 yrs)
11Climate change & severe weatherNot a Threat (in the assessed timeframe)Small (1–10%)Slight (1–10%)Low (Possibly in the long term, >10 yrs)
11.2DroughtsNot a Threat (in the assessed timeframe)UnknownUnknownLow (Possibly in the long term, >10 yrs)
11.4Storms & floodingNot a Threat (in the assessed timeframe)Small (1–10%)Slight (1–10%)Low (Possibly in the long term, >10 yrs)

k Impact – The degree to which a species is observed, inferred, or suspected to be directly or indirectly threatened in the area of interest. The impact of each threat is based on Severity and Scope rating and considers only present and future threats. Threat impact reflects a reduction of a species population or decline/degradation of the area of an ecosystem. The median rate of population reduction or area decline for each combination of scope and severity corresponds to the following classes of threat impact: Very High (75% declines), High (40%), Medium (15%), and Low (3%). Unknown: used when impact cannot be determined (e.g., if values for either scope or severity are unknown); Not Calculated: impact not calculated as threat is outside the assessment timeframe (e.g., timing is insignificant/negligible or low as threat is only considered to be in the past); Negligible: when scope or severity is negligible; Not a Threat: when severity is scored as neutral or potential benefit.

l Scope – Proportion of the species that can reasonably be expected to be affected by the threat within 10 years. Usually measured as a proportion of the species' population in the area of interest. (Pervasive = 71–100%; Large = 31–70%; Restricted = 11–30%; Small = 1–10%; Negligible < 1%).

m Severity – Within the scope, the level of damage to the species from the threat that can reasonably be expected to be affected by the threat within a 10-year or 3-generation timeframe. Usually measured as the degree of reduction of the species' population. (Extreme = 71–100%; Serious = 31–70%; Moderate = 11–30%; Slight = 1–10%; Negligible < 1%; Neutral or Potential Benefit > 0%).

n Timing – High = continuing; Moderate = only in the future (could happen in the short term [< 10 years or 3 generations]) or now suspended (could come back in the short term); Low = only in the future (could happen in the long term) or now suspended (could come back in the long term); Insignificant/Negligible = only in the past and unlikely to return, or no direct effect but limiting.

4.2 Description of threats

The overall province-wide Threat Impact for Dun Skipper is High.Footnote 11 While development is the most notable threat to this species, there are also several lower impact threats. The overall threat considers the cumulative impacts of multiple threats. Note that some anthropogenic disturbance of habitat currently unsuitable for the species, such as clearing of densely vegetated ditches and roadsides, is expected to result in additional areas becoming occupied, which may reduce the impact of these threats. Details are discussed below under the Threat Level 1 headings.

IUCN-CMP Threat 1. Residential & commercial development

Dun Skipper is threatened by cumulative habitat loss from urban and rural land conversion, and subsequent habitat fragmentation. Core habitats affected by development in the Lower Mainland are within the local government jurisdictions of Abbotsford, Mission, Chilliwack, Langley, Fort Langley, and Hope. On Vancouver Island, core areas include the 13 municipalities of Greater Victoria and extend up the southeastern side of Vancouver Island to the Courtenay area. Most of the large habitat patches within these areas are in private ownership (either owned by the local government or timber or development companies) and urban planning projections designate many for housing or commercial development. At present, residential and commercial development primarily threaten potential Dun Skipper habitat in Bevan, Mission, Sahtlam District, Salt Spring Island, Somenos Garry Oak Preserve, Wellington, Denman Island, Maple Bay, Spectacle Lake, and Burns Bog.

1.1 Housing & urban areas

Within the mainland range of Dun Skipper, there have been at least 73 separate housing developments in urban areas with Dun Skipper habitat (Abbotsford, Chilliwack, Agassiz, Maple Ridge, Mission, and Langley) that are ongoing as of 2011 (Greater Vancouver Real Estate 2011). These urban developments include large-scale new communities with new infrastructure, such as schools, roads, and central shopping amenities and, in some cases, golf courses and other recreational infrastructure. Most of this development has been within privately owned natural land within the Sumas Mountain and other areas of rural Abbotsford (see City of Abbotsford 2003, Vedder Mountain, and other natural areas of Chilliwack, within the lower Fraser Valley; Greater Vancouver Real Estate 2011).

Dun Skipper habitat on southeastern Vancouver Island is also threatened from urban and rural land conversion, and subsequent fragmentation of the open sparsely vegetated wetland and Garry oak ecosystem habitat. The uncertainty surrounding land use and the frequently changing land ownership increases the potential threat of habitat conversion. Within the greater Victoria area there are currently or ongoing, a minimum of 12 large-scale urban housing, commercial, or recreational facility (e.g., golf courses) developments on natural habitat totaling greater than 1550 ha that are ongoing or planned for immediate commencement, most within Colwood, Langford, and Central Saanich (Victoria Real Estate Team 2011). These natural areas all have potential Dun Skipper habitat (as assessed through satellite imagery). These developments include large-scale new communities that include infrastructure such as schools and roads.

This threat applies directly to at least 4 populations, including potential habitat on Denman Island, where land is being subdivided and sold to individual landowners (i.e., the butterfly has been recorded from adjacent properties other than the one being developed, but the habitat types are similar).

1.2 Commercial & industrial areas

Industrial and business park expansion plans are published for some municipalities within the lower Fraser Valley (mainland), such as the City in the Country Plan specific to the City of Abbotsford. This plan projects the need for "1,300 acres of employment-generating industrial and business park lands over the next 20 years" with "future residential development accommodated through hillside development…not accommodated by expansion into the Agricultural Land Reserve" (City of Abbotsford 2003).

This threat applies directly to a known Dun Skipper site and habitat on private land adjacent the conserved Burns Bog Ecological Conservancy Area, as a habitat unit is not entirely within conservation land, and a parcel of private land has potential for commercial real estate (industrial park) development.

1.3 Tourism & recreational areas

The demand for tourism and recreational areas within southeastern Vancouver has increased substantially within the past decade. Natural areas continue to be developed into golf courses (e.g., Bear Mountain development [Victoria Real Estate Team 2011]), parks, and recreation facilities (e.g., outside the boundaries of Goldstream Provincial Park). Within existing parks, as well as on regional and municipal properties, recreational development potentially conflict with Dun Skipper conservation. On the northern edge of the Fraser Valley, this threat applies directly to the known Dun Skipper site at the Morris Valley Hemlock Ski Hill (population #22) where a major ski hill expansion has been proposed. BC Parks staff are aware of the Dun Skipper and incorporate this information in their trail planning to avoid potential Dun Skipper habitats in Helliwell, Denman Island, and Burgoyne Bay Provincial Parks (E. McClaren, pers. comm., 2013).

IUCN-CMP Threat 2. Agriculture & aquaculture
2.1 Annual & perennial non-timber crops

Clearing of land for agriculture is ongoing, in small amounts, on private lands throughout the range of Dun Skipper. Land clearing on agricultural land reserves is also ongoing.

2.2 Livestock farming & ranching

Detrimental impacts to Dun Skipper habitat from livestock overgrazing have been recorded on Denman Island. Trampling of sensitive wetland areas often results when livestock congregate adjacent to watercourses. The impacts of grazing are unknown; however, moderate livestock grazing may be beneficial.

IUCN-CMP Threat 3. Energy production & mining
3.2 Mining & quarrying

There is a small possibility roadside gravel extraction or quarrying could occur along the stretch of Dun Skipper sites in the Boston Bar corridor (population #16).

IUCN-CMP Threat 4. Transportation & service corridors
4.1 Roads & railroads

With increasing human population comes the need for associated transportation infrastructure and access to both new and existing urban areas. Proposed transportation routes are often planned through areas that have the least impact to existing private landowners (e.g., land owned by the local or provincial government; land currently within the provincial Agricultural Land Reserve [although the land may be privately owned]; or land through natural areas owned by one private landowner or company). These transportation routes often go through natural areas suitable for Dun Skipper.

Within the geographic range of Dun Skipper, extensive roads and other similar transportation corridors already fragment much of the remaining natural habitat. Increased roads, trails, and corridors lead to further habitat modifications through the spread of introduced species (see IUCN-CMP Threat 8.1) and increased frequency of use by humans (see IUCN-CMP Threat 6.1).

This threat applies to at least 8 Dun Skipper populations (#3, 4, 6, 16, 17, 20, 22, and 25), including a site at Burns Bog (population #20), where a development and an ongoing highway expansion project (South Perimeter Road) are occurring at the bog's margins.

IUCN-CMP Threat 5. Biological resource use
5.3 Logging & wood harvesting

In some areas, forest harvesting may create open habitat for the expansion of Dun Skipper populations. For example, the open, wet, marshy clearings and logged areas of central Denman Island have provided ideal habitat for population expansion to other areas throughout the island. A provincial park has been established recently on the island, covering approximately 75 ha of regenerating (e.g., previously clearcut) forest. A carbon covenant on this property stipulates the property must allow the forest to grow for the use of carbon sequestration. Eventually, these large, open clearcuts will grow and habitat will once again become limited on Denman Island for Dun Skipper. The logging within the Dun Skipper range is thought to be negligible.

IUCN-CMP Threat 6. Human intrusions & disturbance
6.1 Recreational activities

Recreational activities within Dun Skipper habitat include hiking (e.g., Helliwell Provincial Park on Hornby Island) and horseback riding (e.g., on Denman Island). Such activities can result in degradation of habitat quality through soil compaction and can also cause accidental mortality of larvae.

Areas with particularly high recreational use include those habitats within Metro Vancouver and Fraser Valley Regional District parks and within the Capital Regional District. Hiking and related activities may also increase the spread of introduced species (see IUCN-CMP Threat 8). Recreational use of trails for horseback riding is also prominent and likely impacts habitat (e.g., trampling of trails/edges and defecation, which increases the spread of fungus, seeds, etc.). The scope and overall impact of recreational activities as a threat are thought to be negligible.

IUCN-CMP Threat 7. Natural system modifications
7.1 Fire & fire suppression

Fire suppression is ongoing throughout the entire range of Dun Skipper. Within Garry oak and associated habitats, fire suppression has led to further forest succession within these open habitats (Garry Oak Ecosystems Recovery Team 2010), and thus a decline in potential Dun Skipper habitats.

The threat of fire is also present throughout the range of Dun Skipper, particularly within large natural tracts of land as well as areas adjacent to roadways and right-of-ways and in recreational areas where brush burning may be used as a form of fire suppression. Burns Bog periodically experiences ground fires, and although efforts are made to control blazes, fire does impact habitat. Due to the removal of vegetation, fires may adversely affect Dun Skippers by decreasing available moisture retention within habitats, increasing dehydration stress to individuals, and causing direct mortality.

7.2 Dams & water management/use

Human activity, such as ditch creation, clearing the ditch of in-water and streambank vegetation, or flushing the ditch and flooding streambank vegetation throughout the species' historical range, would appear to create habitat suitable for growth of Dun Skipper's larval and nectar host plants, while concurrently destroying other habitats.

7.3 Other ecosystem modifications

Brush clearing and mowing as forms of fire suppression occur on private and public lands throughout the species' range, particularly in areas adjacent to roadways and right-of-ways and in recreational areas. This may adversely affect Dun Skippers by decreasing available moisture retention within habitats, increasing dehydration stress to individuals, and causing direct mortality. Current mowing regimes may pose a minor threat to Dun Skipper habitat in Burgoyne Bay Provincial Park (E. McClaren, pers. comm., 2013).

IUCN-CMP Threat 8. Invasive & other problematic species & genes
8.1 Invasive non-native/alien species

Roadsides can act as corridors into natural habitats and are known to facilitate the rapid spread of introduced species (e.g., plant seeds attach to car tires and become dislodged at new locations) (Trombulak and Frissell 2000). The potential spread of introduced species along roadsides may impact local populations through competition and predation, as well as through changes to native vegetation.

Many of the sites where Dun Skipper has been recorded have become degraded and/or dominated by introduced species such as agronomic grasses and weedy forbs.

Invasive plant species such as Scotch broom (Cytisus scoparius L.) have the ability to fix nitrogen and are known to change vegetation and soil structure (Haubensak and Parker 2004). Invasive species legacy (resulting in long-term ecosystem impacts from prolonged invasive species growth) and increasing the nitrogen availability in the soil may encourage exotic species growth in native grasslands (Huenneke et al. 1990; Maron and Conners 1996). Scotch broom is also associated with suppressed native species richness (Rook et al. 2011) and more specifically is a high threat at Vancouver Island sites, especially to the roadside right-of-ways at Nanaimo Lakes Road (P. Lilley, pers. comm., 2010; J. Heron, pers. comm., 2011) and portions of habitat on Denman Island have abundant Scotch broom (J. Heron, pers. comm., 2010). Dun Skipper habitat at Dog Mountain (population #17), where a gas pipeline crosses along Highway 7 is now covered by invading shrubby vegetation including Himalayan blackberry (Rubus armeniacus) and introduced white virgin's bower (Clematis virginiana) (Knopp et al. 2010). Other sites with high invasive species presence include Hornby Island (Helliwell Provincial Park) with invasive Scotch broom, and the Spectacle Lake and Goldstream areas. Overall, most sites are likely impacted by invasive species.

Eastern Cottontail (Sylvilagus floridanus) and European Rabbit (Oryctolagus cuniculus), both introduced rabbit species, may browse host plants, but herbivory is considered a minor threat.

Invasive plants threaten Dun Skipper habitats within Helliwell Provincial Park, Denman Island Provincial Park (potential habitat, based on known occurrence in adjacent private conservation land), and Burgoyne Bay Provincial Park. Plans to remove English hawthorne from within the Dun Skipper habitat polygons mapped in 2009 (Miskelly 2009) are in place to decrease this threat within Burgoyne Bay Provincial Park (E. McClaren, pers. comm., 2013).

IUCN-CMP Threat 9. Pollution
9.3 Agricultural & forestry effluents

Agricultural and forestry effluents most likely to harm Dun Skipper and its habitat are herbicides used to control vegetation, especially the general use of herbicides to control roadside and right-of-way vegetation on commercial forestry lands. It is unclear how extensive this practice is at present within the range of Dun Skipper.

Dun Skipper is within the introduction range of European Gypsy Moth (Lymantria dispar), and traps to detect introductions of this moth are scattered throughout southern B.C. (B.C. Ministry of Forests, Lands and Natural Resource Operations 2013). A provincial program to detect and eradicate introductions of this moth has been ongoing since 1979 and spray has been applied in numerous areas within the range of Dun Skipper since this time (Figure 5).

If the moth is recorded in abundance (criteria are determined by the provincial Gypsy Moth Committee) ground and aerial spray of Btk (Bacillus thuringiensis kurstaki) are applied to control the moth. Btk is a component of commercial pesticides that use spores of a naturally occurring pathogenic bacterium to control defoliating caterpillars, although the bacterium also affects most non-target butterfly and moth larvae. Btk for European Gypsy Moth is typically applied in early April to early May, which coincides with Dun Skipper larval activity.

The area of Btk application varies yearly and depends on the extent to which gypsy moths are trapped during previous years' surveys. Since trap results are compiled over at least 2 years, should European Gypsy Moth be recorded there would likely be time to seek treatment options rather than simply broadcast aerial sprays. It is unlikely the entire Dun Skipper range would be treated for European Gypsy Moth according to October 2012 trap results; no Btk treatment is planned for 2013 (J. Burleigh, pers. comm., 2012).

Figure 5. Gypsy Moth treatment areas 1979–2010. Note: data points are not exact and do not show the entire treatment area.
Map of Gypsy Moth areas (see long description below)
Long description for Figure 5

Figure 5 depicts the Gypsy moth treatment areas between 1979 and 2010. Areas of treatment are noted in the Vancouver area spanning west, in the Victoria area spanning up alongside the coast until Courtenay, and one area southwest of Squamish.

9.4 Garbage & solid waste

The City of Vancouver manages a municipal waste facility at the edge of Burns Bog. There are no records for Dun Skipper within the municipal waste site; however, there are likely impacts to the surrounding wetlands from the dump. These impacts are unknown.

IUCN-CMP Threat 10 Geological events
10.2. Earthquakes/tsunamis

Some Dun Skipper sites are within the potential flood zone should an earthquake or tsunami occur; specifically Burns Bog Ecological Conservancy Area (population #20), lowland areas of the Fraser Valley, and parts of the Greater Victoria area.

IUCN-CMP Threat 11. Climate change & severe weather
11.2 Droughts

Climate change is a potential threat to the Dun Skipper; primarily due to the impacts such change brings to the wetland ecosystems and plant communities within which the species lives. Increased summer droughts may affect habitat within Dun Skipper sites by decreasing the available site moisture that allows for suitable host plant growth. Droughts may impact host plant timing and senescence of Dun Skipper. By 2050, mean annual temperatures are expected to rise approximately 2 to 3°C (Hebda 1997). Within the Pacific Maritime Ecozone (where Dun Skipper occurs in western Canada), mean temperatures increased by 1.71°C from 1960 to 2006 (Coristine and Kerr 2011). This temperature increase could lead to increase in droughts. The effects on Dun Skipper are unknown.

11.4 Storms & flooding

Flooding could occur at Burns Bog as a result of the effects of climate change; however, it is not thought that this is likely to occur in the next 10 years.

5 Recovery goal and objectives

5.1 Recovery (Population and distribution) goal

The population and distribution goal is to maintain the current populations for Dun Skipper as well as maintain its distribution throughout its range in British Columbia

5.2 Rationale for the population and distribution goal

The population and distribution goal was set to ensure that Dun Skipper does not become Endangered. Dun Skipper is likely to remain Threatened as it has a restricted range in B.C. It is unlikely that new populations will be found that would extend its range (D. Knopp, pers. comm., 2013) such that this species could be downlisted to Special Concern.

The population and distribution goal for Dun Skipper cannot be quantified due to knowledge gaps–population size is unknown at all sites. Studies to date have primarily been surveys focused on recording new sightings and habitat information. Most sightings are of 1–2 individuals (Table 1; B.C. Conservation Data Centre 2013), suggesting it may require multiple surveys over multiple years at the same site before it is detected. Estimating populations is difficult due to the low detection rate for the species, which makes surveys labour-intensive and logistically difficult.

5.3 Recovery objectives

  1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.
  2. To secure protectionFootnote 8 for Dun Skipper habitats within the species' range.
  3. To assess and reduce threats to all known Dun Skipper sites in B.C.
  4. To address knowledge gaps (e.g., population size, host plant requirements) that will enable quantitative population and distribution objectives to be set.

6 Approaches to meet objectives

6.1 Actions already completed or underway

The following actions have been categorized by the action groups of the B.C. Conservation Framework (B.C. Ministry of Environment 2010b). Status of the action group for this species is given in parentheses.

Compile status report (complete)

  • COSEWIC report completed (Shepard 2000b). Update report in progress (April 2013).

Send to COSEWIC (complete)

  • Dun Skipper designated Threatened (Shepard 2000b). Reassessed by COSEWIC in May 2013 as Threatened.

Planning (complete)

  • B.C. Recovery Plan completed (this document, 2013).

Inventory (in progress)

From 2001 to 2011 inventory for Dun Skipper has focused on southeastern Vancouver Island (Guppy and Fischer 2001; Page, Lilley, Heron et al. 2008; Page, Lilley, Miskelly et al. 2008; Page et al. 2009; Page and Lilley 2009; J. Heron, pers. observation, 2012); Denman Island (Guppy et al. 2007; Page et al. 2007; Page, Lilley, Heron et al. 2008), Hornby Island (Page et al. 2007), Salt Spring Island, Galiano Island, Mayne Island, and Gulf Islands National Park Reserve (Guppy 2008). On the southwestern mainland of B.C., search effort has specifically focused on the edges of the species' known range (e.g., Pemberton, Lillooet, and Boston Bar) with the intent to confirm the edges of the species range on the mainland (Knopp et al. 2007, 2009, 2010). Species-specific search effort took place in 2007 and 2009–2011 and amounted to at least 1129 hours, at least 1660.7 km of walking transects, and 4847 km of driving (assessing habitat by slowly traveling logging roads, stopping when good habitat is observed, and completing surveys within such habitat).Additional boat surveys within Harrison and Pitt Lakes have also been completed (62 km by slowly traveling along shorelines, stopping when good habitat is observed, and completing surveys in such habitat; Parkinson et al. 2009).

  • Search effort for Dun Skipper throughout Metro Vancouver parks in the lower Fraser Valley has not yielded any records other than at Metro Vancouver Burns Bog Ecological Conservancy Area.
  • Inventory of Dun Skipper in Burgoyne Bay Provincial Park (Miskelly 2009).

Habitat protection, habitat restoration, and private land stewardship (in progress)

  • Dun Skippers occur on 14 sites managed under the provincial forestry land base. These areas could be potential Wildlife Habitat Areas under the Forest and Range Practices Act. Dun Skipper is currently not listed in the Species at Risk category under this act; however, it is certainly a candidate for this designation and is recommended for inclusion as such.
  • Existing mechanisms that afford habitat protection for Dun Skipper are listed in Table 3.
Table 3. Existing mechanisms that afford habitat protection for Dun Skipper.
Existing regulatory and other protection mechanisms that afford habitat protectionThreato or concern addressedSite

Legal provisions of the B.C. Parks Act and B.C. Ecological Reserves Act

  • Park managers and staff are aware of the species and its habitat needs at Helliwell Provincial Park (E. McClaren, pers. comm., 2013) and Burgoyne Bay Provincial Park (R. Annschild, pers. comm., 2010; C. Retzer Miller, pers. comm., 2010).
1.1
1.2
1.3
6.1
8.1
Helliwell Provincial Park (Hornby Island, 2004), Somenos Garry Oak Preserve (1976), Burgoyne Bay Provincial Park (2008 and 2009). Presence in Goldstream and Spectacle Lake Provincial Parks is unconfirmed.

Regional and municipal owned land

  • These governments are aware of the species and its habitat needs (; M. Fuchs, pers. comm., 2003–2010; M. Merkens, pers. comm., 2005–2010).
1.1
1.2
1.3
6.1
8.1
Francis/King Regional Park (1962) and Thetis Lake Regional Park (both Capital Regional District parks), and Burns Bog Ecological Conservancy Area (Metro Vancouver Park).

Conservation covenants on Denman Island

  • Contain habitat where Dun Skipper has been observed.
1.1
1.2
1.3
8.2
Denman Island Conservancy private conservation lands: Central Park (59.5 ha) and property owned by the Denman Conservancy named "Settlement Lands" (160 ha) (Denman Conservancy Association 2010; A. Fyson, pers. comm., 2010).
Legal provisions of the federal Species At Risk Actblank Recorded from two federal Indian Reserves: Sho-ook IR 5 and Soowahlie IR 14.

o Threat numbers according to the IUCN-CMP classification (see Table 2 for details).

6.2 Recovery planning table

Table 4. Recovery planning table for Dun Skipper.
ObjectiveActions to meet objectivesThreat p or concern addressedPriorityq
Objective 1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.Complete spatial mapping of all suitable Dun Skipper habitats within the B.C. range using information in habitat description. Delineate and label these spatial areas into sites. Include known sites in this spatial mapping.Knowledge GapEssential
Objective 1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.Create a habitat suitability rating system that categorizes Dun Skipper sites as high, medium, or low for inventory and/or monitoring. This will enable sites to be compared for presence/absence of certain correlating habitat elements and assist with habitat suitability rating as well as describing survival/recovery habitat.Knowledge GapEssential
Objective 1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.

From spatial mapping:

  • prioritize sites for Dun Skipper inventory based on habitat suitability rating, previous/ongoing inventory, or known records;
  • categorize sites by habitat protection measure options based on land tenure (e.g., level of government, private, agricultural lands) and other pertinent information.
Knowledge GapEssential
Objective 1. To identify and prioritize Dun Skipper habitat throughout the species' range in B.C.Work with South Coast Conservation Program to contact private landowners with high priority sites and request for inventory.Knowledge GapEssential
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Where Dun Skipper is recorded on Crown lands (federal and provincial), initiate protection measures under existing legislation and government policy.AllEssential
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Recommend Dun Skipper to be listed as a species at riskr under the Forest and Range Practices Act and the Oil and Gas Activities Act.3.2
5.3
Essential
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Work with municipalities to use existing environmental protection tools under current legislation (e.g., Sensitive Development Permit Areas, Riparian Areas Regulation).
In addition, collaboratively work together to outline and formulate new environmental protective tools that are specific to each local government, to enable locally led protection for private land within each jurisdiction (e.g., establish wording to assist with bylaws, determine Sensitive Development Permit Areas, and develop pesticide restrictions).
AllEssential
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Work with South Coast Conservation Program to contact private landowners regarding stewardship options and other protective measures at sites where inventory resulted in Dun Skipper occurrences. Combine information with other species at risk habitat needs, and define priority sites for stewardship and protection opportunities.Knowledge GapNecessary
Objective 2. To secure protection for Dun Skipper habitats within the species' range.

Work with South Coast Conservation Program, Garry Oak Ecosystems Recovery Team, additional non-government organizations, as well as government partners, to increase public understanding and knowledge of Dun Skipper and associated threats to the species. (e.g., prepare a fact sheet or at-risk brochure):

  • promote the inclusion of the species in interpretive materials by local government bodies and by provincial and national parks within the species' potential range;
  • provide information on the species at the B.C. Conservation Data Centre website, other provincial websites on species at risk, and the federal agencies responsible for species at risk;
  • develop and present workshops on conservation and restoration of remnant forest ecosystems in the lower Fraser Valley lowlands and southern Vancouver Island.
6.1
8.1
9.3
Necessary
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Spatially map areas that are protected through stewardship and after 5 years of stakeholder engagement, evaluate this approach.Knowledge GapNecessary
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Work with staff of parks and protected areas to ensure Dun Skipper is integrated into park management planning activities. These include actions such as signage, vegetation management options around occupied habitats, and identification training for parks staff.6.1
7.1
7.3
8.1
9.3
Essential
Objective 2. To secure protection for Dun Skipper habitats within the species' range.Amend provincial park management plans to include management practices that enable the protection of Dun Skipper habitat.6.1
7.1
7.3
8.1
9.3
Essential
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.

When completing inventory, attempt to list, quantify, and rate threats to habitat at each known site through standard protocol thereby assessing reasons Dun Skipper may or may not be present within certain habitats.

Use this site-specific threat information to inform best management practices and advice during environmental assessments.

Knowledge gap
All
Essential
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.Overlay spatial information that shows flood information, forest fire information, immediate development applications (e.g., Water Act approval applications, sensitive ecosystems, and other relevant environmental information) onto completed spatial mapping of all suitable Dun Skipper habitats within the B.C. range. This will reveal habitats that may be more vulnerable to these related threats and allow for a more accurate estimation of impact should one of these threats occur.1.1
1.2
1.3
7.1
11.2
11.4
Beneficial
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.Investigate distribution and habitat use patterns of Dun Skipper in relation to potential Gypsy Moth spray.Knowledge gap
9.3
Beneficial
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.Work with land developers to ensure that they include the needs of Dun Skipper in land use plans for urban and rural areas containing high priority habitats.1.1
1.2
1.3
Essential
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.Specific management practices guidelines for Dun Skipper for each landowner or land manager, specific to the threats of the site have been drafted by 2016.AllEssential
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.In parks and recreational areas, identify site-specific threats to minimize damage to Dun Skipper habitat caused by erosion and destruction of vegetation (e.g., fire management prevention or suppression activities); restrict intensive recreational activities use within known occupied habitats; and implement invasive species removal/management programs.6.1
7.1
8.1
9.3
Essential
Objective 3. To assess and reduce threats to all known Dun Skipper sites in B.C.As part of long-term monitoring program, assess changes in habitat use and distribution due to the effects of climate change (e.g., more frequent drought).11.2Beneficial
Objective 4. To address knowledge gaps (e.g., habitat requirements, biological needs, and ecological factors) that currently prevent quantitative population and distribution objectives from being established.Develop monitoring program at known sites. Investigate the vegetative habitat components of each site, and determine what habitat attributes are favoured by Dun Skipper. Gather information on, for example, movements, subsequent threats (e.g., invasive species competition), and other factors. Investigate and observe the butterfly and its natural history (e.g., host plants).Knowledge gapNecessary

p Threat numbers according to the IUCN-CMP classification (see Table 2 for details).

q Essential (urgent and important, needs to start immediately); Necessary (important but not urgent, action can start in 2–5 years); or Beneficial (action is beneficial and could start at any time that was feasible).

r Listed species require special management attention to address the impacts of forest and range activities and/or the impacts of oil and gas activities on Crown land as described in the Identified Wildlife Management Strategy (Province of British Columbia 2004).

7 Information on habitat needed to meet recovery goal

Threats to Dun Skipper habitat have been identified. To help meet the population and distribution goal for this species, it is recommended that specific habitat attributes be identified for Dun Skipper. In addition, it is recommended that locations of survival/recovery habitat be geospatially described on the landscape to mitigate habitat threats and to facilitate the actions for meeting the population and distribution goal.

7.1 Description of the species' survival and recovery habitat

Information on habitat requirements for Dun Skipper is provided in Section 3.3.1 and provides a partial description of the biophysical attributes of survival/recovery habitat. Note the specific moisture levels, plant information, and/or species composition is unknown and requires further study. Additional work needs to be done so that survival/recovery for Dun Skipper habitat in B.C. can be spatially described using maps (see Section 7.2).

At minimum, survival/recovery habitat should include:

  • the known area of occupancy of the species and the associated potential error from geographic positioning system (GPS) units (uncertainty may range up to 25 m depending on the GPS unit accuracy)
  • adjacent suitable habitat. This should extend to a minimum of 50 m from the occupied area and uncertainty to maintain minimum constituent microhabitat properties where the butterflies are found (based on average edge effects distances in coastal forests) (Kremsater and Bunnell 1999). Unsuitable habitat (e.g., parking lot, works yard, or maintenance facility) found within this polygon should be excluded.

Survival/recovery habitat may also include the entire portion of the habitat that is associated with, and is integral to, the production and maintenance of suitable habitat conditions, and that provides ecological context for occupied microhabitats.

7.2 Studies needed to describe survival/recovery ha

General habitat requirements are known for Dun Skipper (see Section 3.3.1). However, biophysical attributes of survival/recovery habitat for Dun Skipper should include a minimum density of larval and nectar host plants. It is recommended that outstanding work required to quantify specific habitat requirements for the species be completed and that the survival/recovery habitat be geospatially described at each known location to facilitate the actions for meeting the population and distribution goal.

Table 5. Studies needed to describe survival/recovery habitat to meet the population and distribution goal for Dun Skipper.
Description of activityOutcome/rationaleTimeline
Conduct habitat assessments that record descriptive habitat measures at known Dun Skipper sites (e.g., slope, aspect, vegetative components, soil type).
  • Enable comparison of sites for habitat values
2013–2018
Conduct mark–recapture studies at sites with high known abundance.
  • Gain a better understanding of home range, spatial habitat use, etc.
2013–2018
Spatially define habitat polygons at Dun Skipper sites (with suitable habitat and higher abundance counts) using plant community classifications and other existing resources for describing habitat attributes.
  • Enable spatially defined habitat at each site, to direct actions to minimize threats.
2013–2018
Define habitat use by life history stage.
  • Clarify and quantify components of habitat that are used at different life stages, and thus survival/recovery habitat for different life stages.
2013–2018
Map Dun Skipper habitat using information gained through surveys (e.g., using standard protocol for gathering habitat information).
  • Maps of survival/recovery habitat
2013–2018

8 Measuring progress

The successful implementation of recovery actions for Dun Skipper involves monitoring of populations and habitat trends through time. Dun Skipper has an annual life cycle thus population sizes may vary substantially from year to year and overall population (on a scale of decades) may vary within areas of suitable habitat. Population monitoring will allow for an indication of possible decline at a given site, changes in area of extent at a given site, and whether the number of extant populations is stable or increasing. The recovery plan will be reviewed in 5 years to assess progress and to identify additional approaches or changes that may be required to achieve recovery.

The performance indicators presented below provide a way to define and measure progress toward achieving the population and distribution goal and recovery objectives. Performance measures are listed below for each objective.

Measurables for objective 1:

  • Spatial mapping of potential Dun Skipper habitat within its B.C. range is completed by 2016.
  • Identification and inventory of 5% of potential habitat within the species' range is completed each year.

Measurables for objective 2:

  • Habitat protection plan, including stewardship recommendations, developed for known Dun Skipper locations by 2016.
  • Dun Skipper has been recommended for listing as a species at risk under the provincial Forest and Range Practices Act and the Oil and Gas Activities Act by 2016.
  • Stewardship agreements and/or covenants for 25% of known Dun Skipper sites have been established on local government/private lands by 2019.

Measurables for objective 3:

  • Development of management practice guidelines for Dun Skipper that are specific to the threats of a site for each landowner or land manager have been drafted by 2016.
  • Impact of the main threats to the Dun Skipper sites have been addressed and mitigation initiated by 2016.

Measurable for objective 4:

  • Studies addressing knowledge gaps have been initiated by 2016. Specifically host plant(s), threats to site(s) from natural succession, and invasive species.

9. Effects on other species

In addition to Dun Skipper, approximately 379 provincially listed (Red- or Blue-listed) species at risk inhabit the coastal lowlands of southeastern Vancouver Island and the lower Fraser Valley (B.C. Conservation Data Centre 2013); more than 115 of these species have been assessed by COSEWIC (COSEWIC 2013; B.C. Conservation Data Centre 2013).

Coordinated, ecosystem-based approaches are needed to ensure Dun Skipper recovery activities are compatible with recovery activities for other species and ecosystems within its range. Stewardship activities that result in protection or public awareness of the conservation values of Dun Skipper habitat are expected to benefit all wild native species that use these ecosystems. The protection and/or suitable management of key areas will help to restore these ecosystems over the long term. There are no negative impacts anticipated as a result of recovery efforts for this species.

Survey and habitat assessments for Dun Skipper may increase knowledge about other butterfly species at risk within similar habitats and overlapping geographic range including Taylor's Checkerspot (Euphydryas editha taylori) (SARA-listed Endangered 2012). This species occurs in similar habitats on Denman Island.

The lowland ecosystems of the Lower Mainland and southern Vancouver Island are overall at risk from urban and rural development, fragmentation, and ecological changes from introduced species. Dun Skipper habitats are important for many species, including additional at-risk arthropods. These ecosystems would benefit from a detailed evaluation of habitat quality and threats facing them from human activities, and habitat work for Dun Skipper will benefit this ecosystem as a whole.

10 References

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Appendix 1. IUCN threats to each biological population.
PopulationCDC s occurrence name1.11.21.32.12.23.24.14.27.17.38.18.29.39.410.211.211.4
Number of populations affected by threatblank 41111184252025252511251
1Cowichan Station (Vancouver Island)00000000111110010
2Mill Bay, Malahat Ridge (Vancouver Island)00000000111110010
3Malahat, Colpman and van Home Creeks; Spectacle Lake (Vancouver Island)10000010111110010
4Mount Tzuhalem; Maple Bay (Vancouver Island)00000010111110010
5Cobble Hill (Vancouver Island)10000000111110010
6Nanaimo River (Vancouver Island)00000011111110010
7Port Alberni, northeast of (Vancouver Island)00000000111110010
8Mount Currie (Mainland)10000000111110010
9Shawnigan Lake, west of (Vancouver Island)00000000111110010
10Big Sicker Mountain; Little Sicker Mountain; Mount Prevost; Somenos (Vancouver Island)00000000111110010
11Powell River (Sunshine Coast, mainland)00000000101110010
12Koksilah River (Vancouver Island)00000000101110010
13Colquitz; Francis/
King Park and Thetis Lake Park (Vancouver Island)
00000000111110010
14Wellington (Vancouver Island)00000000111110010
15Goldstream (Vancouver Island)00000000111110010
16Boston Bar (lower Fraser Valley)00000011111110010
17Dog Mountain (lower Fraser Valley)00000010111110010
18Denman Island (northern Gulf Islands)10011000111110010
19Salt Spring Island; southeast (southern Gulf Islands)00000000111110010
20Burns Bog (Lower Mainland)01000011101111111
21Hornby Island (northern Gulf Islands)00000000101110010
22Morris Lake, west of (Lower Fraser Valley)00100011111110010
23Soowahlie Indian Reserve 14 (lower Fraser Valley)00000100101110010
24Yale (lower Fraser Valley)00000000111110010
25Lytton, south of (lower Fraser Valley)00000010111110010

s CDC = B.C. Conservation Data Centre.

Footnotes

Footnote 8

Protection can be achieved through various mechanisms including: voluntary stewardship agreements, conservation covenants, sale by willing vendors on private lands, land use designations, and protected areas.

Return to footnote 8 referrer

Footnote 9

Past threats may be recorded but are not used in the calculation of Threat Impact. Effects of past threats (if not continuing) are taken into consideration when determining long-term and/or short-term trend factors (Master et al. 2009).

Return to footnote 9 referrer

Footnote 10

It is important to distinguish between limiting factors and threats. Limiting factors are generally not human induced and include characteristics that make the species or ecosystem less likely to respond to recovery/conservation efforts.

Return to footnote 10 referrer

Footnote 11

The overall threat impact was calculated following Master et al. (2009) using the number of Level 1 Threats assigned to this species where Timing = High or Moderate. This includes 1 Medium and 7 Low (Table 2). The overall threat considers the cumulative impacts of multiple threats.

Return to footnote 11 referrer

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