COSEWIC Assessment and Status Report on the Gold-edged Gem Schinia avemensis in Canada 2016

Photo of a Gold-edged Gem, on a sunflower
Photo: Gold-edged Gem © R. Foster

Endangered
2016

Table of contents

List of figures

  • Figure 1. Adult male Gold-edged Gem from Manitoba (left; G. Anweiler photo) and darker-coloured individual from Saskatchewan (right; A. Harris photo).
  • Figure 2. Known global range of Gold-edged Gem in relation to major dunes (Wolfe et al. 2002).
  • Figure 3. Known Canadian range of the Gold-edged Gem.
  • Figure 4. Gold-edged Gem habitat with sparse Prairie Sunflowers along leading margin of active sand dune in the Great Sand Hills east of Fox Valley (SK), 7 August 2015. See Figure 8 for GoogleEarth imagery of this site.
  • Figure 5. Gold-edged Gem habitat at Antelope Sand Hills (SK) blowout with abundant Prairie Sunflowers, 5 August 2015.
  • Figure 6. Extensive sand dune with sparse vegetation and ATV tracks in the Great Sand Hills south of Portreeve (SK). Approximately 20 Prairie Sunflowers (arrow) but no Gold-edged Gem were observed on 5 August 2015.
  • Figure 7. Slope with Prairie Sunflowers and Gold-edged Gems that was disturbed by cattle tracks in the Great Sand Hills east of Fox Valley (SK), 7 August 2015. See Figure 8 for GoogleEarth imagery of this site.
  • Figure 8. Comparison of two separate sites where Gold-edged Gems were observed (yellow arrows) in atypical habitat along a slope eroded by cattle trails (upper GoogleEarth image) and more typical dune habitat (lower image, same scale) 1.5 km away on August 7, 2016 in the Great Sand Hills near Fox Valley. See Figures 4 and 7 for photos of these sites.
  • Figure 9. Historical trends of dune stabilization at eight sand hills with Gold-edged Gem subpopulations (Hugenholtz et al. 2010).

List of tables

  • Table 1. Known Canadian occurrences of the Gold-edged Gem (GEG), Schinia avemensis.
  • Table 2. Summary of recent (post-2000) surveys and observations for the Gold-edged Gem in Canadaa.
  • Table 3. Number of mapped (Wolfe 2010) dunes and blowouts within the known Canadian range (i.e., expected range based on geographic proximity) of Gold-edged Gem (GEG) in relation to past survey effortg.
  • Table 4. Viability within each habitat patch for Gold-edged gem (e.g., is a habitat patch smaller than what would be required to support a viable population?). A = Available open-sand habitat (D/BO = dunes or blowouts) within the SH. B = Inferred habitat occupancy based on recorded occurrences and search effort.
  • Table 5. Number of index of area of occupancy (IAO) 2x2 km2 grid squares for Sand Hills. 18 of 31 grid squares (58%) are from sand hills considered not viable within
    Table 4.

List of appendices

  • Appendix 1. IUCN Threats Calculator results for Gold-edged Gem (Schinia avemensis) in Canada.

Document information

COSEWIC
Committee on the Status
of Endangered Wildlife
in Canada

COSEWIC logo

COSEPAC
Comité sur la situation
des espèces en péril
au Canada

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

COSEWIC. 2016. COSEWIC assessment and status report on the Gold-edged Gem Schinia avemensisin Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 49 pp. (Species at Risk Public Registry website).

Previous report(s):

COSEWIC 2006. COSEWIC assessment and status report on the Gold-edged Gem Schinia avemensisin Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 26 pp.

Production note:

COSEWIC would like to acknowledge Allan Harris and Robert Foster (Northern Bioscience) for writing the status report on Gold-edged Gem, Schinia avemensis in Canada, prepared under contract with Environment and Climate Change Canada. This report was overseen and edited by Paul Grant, Co-chair of the COSEWIC Arthropods Specialist Subcommittee.

For additional copies contact:

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

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

Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur L’héliotin d’Aweme (Schinia avemensis) au Canada.

Cover illustration/photo:

Gold-edged Gem -- Cover photo by R. Foster.


COSEWIC assessment summary

Assessment summary – November 2016

Common name:
Gold-edged Gem
Scientific name:
Schinia avemensis
Status:
Endangered
Reason for designation:
This moth is a habitat specialist that needs active dunes or blow-outs with populations of Prairie Sunflower, its sole larval host plant. Large-scale decline in its habitat through dune stabilization has resulted in a more fragmented landscape and a corresponding reduction in the moth. Population viability of this moth at a number of small sand hills is uncertain.
Occurrence:
Alberta, Saskatchewan, Manitoba
Status history:
Designated Endangered in April 2006. Status re-examined and confirmed in November 2016.

COSEWIC executive summary

Gold-edged Gem
Schinia avemensis

Wildlife species description and significance

The Gold-edged Gem is a small (16-20 mm wingspan), day-flying, noctuid (cutworm or owlet) moth in the subfamily Heliothinae (Flower Moths). These moths have greenish-brown and maroon, or mostly maroon, forewings crossed by two partial, ochre yellow bands. There is also a prominent yellow band along most of the distal edge of the forewing, hence the common name. There are no named subspecies. The early stages (egg, larvae, and pupae) are unknown.

Distribution

In Canada, Gold-edged Gems are known from 35 occurrences in 14 sand hills in southern Manitoba, southwestern Saskatchewan, and adjacent Alberta within the Prairie Ecozone. Elsewhere, they are known only from three sites in Colorado.

Habitat

In Canada, Gold-edged Gems always occur within active sand dunes and blowouts, in close association with the presumed larval host plant, Prairie Sunflower. Most of the 35 known occurrences are in small dunes or blowouts less than 1 ha in size, with the remaining portions of the dunes now stabilized by vegetation. Over the last 100 years, the active dune habitat on which they depend has significantly declined.

Biology

Adult Gold-edged Gems are active during the day. They can be found resting on, or flying among, the presumed larval host plants or resting on and nectaring at nearby blossoms. They are single-brooded, with adults of the Canadian population observed from July 10 to August 23. The presumed larval host is the native Prairie Sunflower; it and Rush Skeletonplant are the primary nectar sources used by adult moths.

Population size and trends

The number of sites occupied by the Gold-edged Gem in Canada appears to be relatively stable, but likely has declined from historical levels due to habitat loss. There are too few data available on which to base useful population estimates.

Threats and limiting factors

The primary limiting factor is availability of active sand dunes or blowouts that support colonies of the presumed larval host plant. The major threat to the long-term survival of the species appears to be the loss of habitat resulting from the stabilization of active sand dunes by both native and introduced vegetation. This natural process is largely driven by regional climate trends, but has accelerated over the last 150 years, in part due to reduced wildfire, extirpation of Bison, and other factors.

Protection, status, and ranks

Most of the known sites have secure tenure on leased Crown land or community pastures, or within or provincial parks (Douglas, Spruce Woods) or the CFB Suffield National Wildlife Area. Only two sites are located on private land, and one is on First Nation lands.

The Gold-edged Gem is listed as Endangered under federal Species at Risk Act and the Manitoba Endangered Species and Ecosystems Act. It is ranked by NatureServe as G2 globally, N1 nationally, and S1 in each of the provinces in which it occurs.


Technical summary

Scientific name:
Schinia avemensis
English name:
Gold-edged Gem
French name:
Héliotin d’Aweme
Range of occurrence in Canada:
Alberta, Saskatchewan, Manitoba

Demographic information

Demographic information of the species
Summary itemsInformation
Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines (2011) is being used)1 year, longer diapause over more than 1 year is possible
Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?Inferred decline based on decreased habitat
Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]Unknown
[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations].Unknown
[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations].Unknown
[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future.Unknown
Are the causes of the decline a. clearly reversible and b. understood and c. ceased? Inferred decline is probably due to habitat loss and not clearly reversible or ceased.a. No
b. Yes
c. No
Are there extreme fluctuations in number of mature individuals?Unknown

Extent and occupancy information

Extent and occupancy information of the species
Summary itemsinformation
Estimated extent of occurrence121,000 km2
Index of area of occupancy (IAO) (Always report 2x2 grid value).500 km2
Is the population “severely fragmented” ie. is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?

a. Yes

b. Yes

Number of locations (use plausible range to reflect uncertainty if appropriate)
(Note: See Definitions and abbreviations on COSEWIC website and IUCN (Feb 2014) for more information on this term.)
At least 14, with each sand hill representing at least one location, because local land management practices can influence the rate of dune succession.
Is there an [observed, inferred, or projected] decline in extent of occurrence?Yes, inferred
Is there an [observed, inferred, or projected] decline in index of area of occupancy?Yes, inferred
Is there an [observed, inferred, or projected] decline in number of subpopulations?Yes, inferred decline due to loss of habitat
Is there an [observed, inferred, or projected] decline in number of “locations”?
(Note: See Definitions and abbreviations on COSEWIC website and IUCN (Feb 2014) for more information on this term.)
Yes, inferred decline due to loss of habitat
Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes, inferred decline in habitat area and quality.

Hugenholtz et al. (2010) documented a 47% decline of bare sand in 36 years at 8 sites. Assuming a constant rate of decline, this would equate to a decline of 13% over ten years.

Are there extreme fluctuations in number of subpopulations?Unknown

Are there extreme fluctuations in number of “locations”?
(Note: See Definitions and abbreviations on COSEWIC website and IUCN (Feb 2014) for more information on this term.)

No
Are there extreme fluctuations in extent of occurrence?No
Are there extreme fluctuations in index of area of occupancy?No

Number of mature individuals (in each subpopulation)

Number of mature individuals of the species
Subpopulations (give plausible ranges)N Mature Individuals
-unknown; estimate in the range of 3000-5000
Total-

Quantitative analysis

Quantitative analysis of the species
Summary itemsInformation
Probability of extinction in the wild is at least [20% within 20 years or 5 generations, or 10% within 100 years].Quantitative analysis was not done

Threats (actual or imminent, to populations or habitats, from highest impact to least)

Was a threats calculator completed for this species and if so, by whom? Yes, December 2015. Overall Threat Impact was considered Medium.

7.3 Other ecosystem modifications (Medium Impact)

Threats calculator (See Appendix 1).

Rescue effect (immigration from outside Canada)

Rescue effect of the species
Summary itemsInformation
Status of outside population(s) most likely to provide immigrants to Canada.NA
Is immigration known or possible?Unlikely. Nearest known subpopulation is at least 1100 km away in Colorado. Other unsurveyed sand hills in U.S. are more than 100 km from the nearest Canadian subpopulation.
Would immigrants be adapted to survive in Canada?Possibly, same presumed host plant but climate is colder.
Is there sufficient habitat for immigrants in Canada?Probably. Apparently suitable habitat occurs appears to be currently unoccupied
Are conditions deteriorating in Canada?
See Table 3 (Guidelines for modifying status assessment based on rescue effect).
Yes. Habitat is being lost through dune stabilization

Are conditions for the source population deteriorating?
See Table 3 (Guidelines for modifying status assessment based on rescue effect).

NA

Is the Canadian population considered to be a sink?
See Table 3 (Guidelines for modifying status assessment based on rescue effect).

No. There is likely no international movement.
Is rescue from outside populations likely?No.

Data-sensitive species

Data-sensitive information of the species
Summary itemsInformation
Is this a data sensitive species?No.

Status history

COSEWIC: Designated Endangered in April 2006. Status re-examined and confirmed in November 2016.

Status and reasons for designation:

Status and reasons for designation
Summary itemsInformation
Status:Endangered
Alpha-numeric code:B2ab(ii,iii)
Reasons for designation:This moth is a habitat specialist that needs active dunes or blowouts with populations of Prairie Sunflower, its sole larval host plant. Large-scale decline in its habitat through dune stabilization has resulted in a more fragmented landscape and a corresponding reduction in the moth. Population viability of this moth at a number of small sand hills is uncertain.

Applicability of criteria:

Applicability of criteria
Summary itemsInformation
Criterion A
(Decline in total number of mature individuals):
Not applicable. There is insufficient trend information.
Criterion B
(Small distribution range and decline or fluctuation):
Meets Endangered B2ab(ii,iii) because IAO is under the threshold of 500 km², habitat quality and IAO are continuing to decline and the species as a whole is considered severely fragmented.
Criterion C
(Small and declining number of mature individuals):
Not applicable. Insufficient data to estimate decline in total number of mature individuals, number of mature individuals and subpopulations.
Criterion D
(Very small or restricted population):
Not applicable. Insufficient data on number of mature individuals within population.
Criterion E
(Quantitative analysis):
Not applicable. Insufficient data on this species exists to make population projections showing the probability of extinction or extirpation in the wild.

Preface

Gold-edged Gem (Schinia avemensis) was assessed as Endangered in April 2006 and listed as such under Schedule 1 of the federal Species at Risk Act in the same year. Since the initial status report, new information has been gathered on the Canadian distribution, habitat, host plants, natural history and site specific threats. Since the last status report, Gold-edged Gem has been documented at 35 individual sand dunes and blowouts in 14 separate sand hills. This increase from four known Canadian sites in 2006 is due to additional survey effort in 2008-2011 and 2015, rather than actual range expansion. There has also been a corresponding increase in extent of occurrence from 70,500 km2 in 2006 to 121,000 km2 in 2015, which is also a result of additional survey effort. However, large-scale decline in its habitat through dune stabilization has resulted in a more fragmented landscape and a corresponding reduction in the moth. Population viability of this moth at a number of small sand hills is uncertain.

COSEWIC history

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

COSEWIC mandate

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

COSEWIC membership

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

Definitions (2015)

Wildlife species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.
Extinct (X)
A wildlife species that no longer exists.
Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.
Endangered (E)
A wildlife species facing imminent extirpation or extinction.
Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.
Special concern (SC)
(Note: Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.)
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.
Not at risk (NAR)
(Note: Formerly described as “Not In Any Category”, or “No Designation Required.”)
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
Data deficient (DD)
(Note: Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” [insufficient scientific information on which to base a designation] prior to 1994. Definition of the [DD] category revised in 2006.)
A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.


Wildlife species description and significance

Name and classification

Order: Lepidoptera - butterflies and moths

Superfamily: Noctuoidea Latreille, 1809

Family: Noctuidae Latreille, 1809 - owlet or cutworm moths

Subfamily: Heliothinae Boisduval, 1828 - flower moths

Genus: Schinia Hübner, 1818

Species: Schinia avemensis (Dyar 1904)

There are no named subspecies but the taxonomic status is being reviewed as part of a larger review of the North American Heliothinae (Harp pers. comm. 2015).

Synonyms: Originally described as Pseudotamila avemensis Dyar (Dyar 1904).

Moths of North America (MONA) Catalogue No.: 11100. Heritage identifier number IILEYMP180.

Type Specimens: Two male syntypes (one apparently lost) CAN., MB, Aweme. The extant type specimen is deposited in the United States National Museum as type #7734 (Hardwick 1996).

French Name: Héliotin d’Aweme

Morphological description

Gold-edged Gems (Figure 1) are relatively small (16-20 mm wingspan), stout-bodied moths. They have greenish-brown and maroon to mostly maroon forewings that are crossed by two partial ochre-yellow bands. There is a prominent yellow band along most of the forewing terminus (hence the common name). The hind wings and most of the body are black. Females are slightly larger and darker than males. The ventral surfaces of both sexes are alike, black except for a prominent white wedge at the apex of the forewings. The head is pale yellow while the thorax and abdomen are black. A formal description, including descriptions and illustrations of male and female genitalia, is available in Hardwick (1958). Gold-edged Gem specimens from Manitoba are lighter coloured than those from Colorado, with specimens from Alberta and Saskatchewan typically intermediate in appearance (Figure 1).

Figure 1. Adult male Gold-edged Gem from Manitoba (left; G. Anweiler photo) and darker-coloured individual from Saskatchewan (right; A. Harris photo).
Two photos of the Gold-edged Gem. (see long description below)
Long description for Figure 1

Two photos of the Gold-edged Gem (dorsal views). One shows an adult male specimen from Manitoba. The other shows a darker-coloured live moth from Saskatchewan. on a sunflower. The Gold-edged Gem has greenish-brown and maroon, or mostly maroon, forewings crossed by two partial, ochre yellow bands. There is also a prominent yellow band along most of the distal edge of the forewing, The hindwings and most of the body are black.

The immature stages (egg, larva and pupa) of Gold-edged Gem are undescribed.

Population spatial structure and variability

The subpopulation in Manitoba is separated from the Saskatchewan-Alberta occurrences by 520 km, and the Alberta-Saskatchewan subpopulation is approximately 1100 km from the nearest Colorado subpopulation. However, recent DNA analysis shows no significant genetic differences among these subpopulations and they will continue be treated as one species in an upcoming Heliothinae treatise (Harp pers. comm. 2015). There are apparently no closely related species, and no evidence, and little likelihood, of hybridization (COSEWIC 2006).

Designatable units

All Canadian Gold-Edged Gem subpopulations fall within the Prairie Ecoregion (COSEWIC 2006) and are considered one designatable unit. The Manitoba subpopulation may be discrete from Saskatchewan/Alberta subpopulations, because there are approximately 500 km separating the nearest occurrences, and there are no known subpopulations in the adjacent U.S. that could potentially link them. However, there has been relatively little survey effort in southeastern Saskatchewan and adjacent states, and there may be additional undiscovered subpopulations. Despite some colour differences, there are no significant genetic differences among U.S., Manitoba, Saskatchewan/Alberta subpopulations (Harp pers. comm. 2015) and they use similar habitats and the same host plant (presumed) throughout their range. As a result, these subpopulations are not considered to represent separate evolutionary significant units.

Special significance

The Gold-edged Gem is a globally threatened species whose main global range and subpopulations are found in the Canadian prairies. Although it is a small, relatively inconspicuous insect, it is a member of a highly specialized dune dwelling community consisting of a number of unique plants and animals restricted to the “islands” of active sand dunes left thousands of years ago by the melting of the glaciers. It is emblematic of disappearing natural sand dune habitats that are also home to other imperilled taxa such as Ord’s Kangaroo Rat (Dipodmys ordii), Dusky Dune Moth (Copablepharon longipenne), Pale Yellow Dune Moth (C. grandis), Gibson’s Big Sand Tiger Beetle (Cicindela formosa gibsoni), and Western Spiderwort (Tradescantia occidentalis).


Distribution

Global range

The global range of the Gold-edged Gem extends from southern Manitoba across the Prairies to southeastern Alberta, and south to central Colorado (Figure 2). Undocumented occurrences probably exist throughout its range (NatureServe 2015; Opler pers. comm. 2015), as there appears to have been limited targeted survey effort for this species in the U.S. The vast majority (>80%) of the Gold-edged Gem’s known global distribution and abundance is found in Canada.

In the United States, Gold-edged Gems are known from only three occurrences, all within south-central Colorado (Harp pers. comm. 2015). It is fairly common at the Great Sand Dunes National Monument in Alamosa and Saguache counties, and has also been collected near Roggen in Weld County, approximately 300 km farther north (Pineda et al. 1999; Weissmann and Kondratieff 1999; Opler pers. comm. 2015).

Figure 2. Known global range of Gold-edged Gem in relation to major dunes (Wolfe et al. 2002).
Map of global distribution of the Gold-edged Gem (see long description below)
Long description for Figure 2

Map showing the global distribution of the Gold-edged Gem, which extends from southern Manitoba across the Prairies to southeastern Alberta, and south to central Colorado. Over 80 percent of the known global distribution is in Canada. Occurrences are indicated by symbols; major dune areas are shaded.

Canadian range

The Canadian range of the Gold-edged Gem extends from Spruce Woods Provincial Park in southwestern Manitoba, through southern Saskatchewan to southeastern Alberta (Figure 3), but is severely fragmented in small, discrete areas of suitable dune habitat. The historical range is essentially the same as the current range. Although the presence of the Gold-edged Gem in southern Saskatchewan and Alberta was unsuspected prior to 2004, a previously unidentified museum specimen collected at Medicine Hat in southwestern Alberta in 1939 indicates they have been there for many years (COSEWIC 2006).

All Canadian subpopulations of Gold-edged Gems are located within the Prairie National Ecological Area (ESWG 1995). The Manitoba site is within the Aspen Parkland Ecoregion in a humid to sub-humid region. The Saskatchewan-Alberta sites are located within the more arid Mixed Grassland Ecoregion (Padbury and Acton 1991; Wolfe 1997). The Dundurn Sand Hills near Saskatoon represent the northern limit of the Gold-edged Gem’s range, as it has not been found north of 52° in the North Battleford (SK) or Wainwright (AB) sand hills (Curteanu et al. 2011). The Gold-edged Gem record from northern Manitoba (Moth Photographers Group 2015) is erroneous.

Figure 3. Known Canadian range of the Gold-edged Gem.
Map of Canadian distribution of the Gold-edged Gem (see long description below)
Long description for Figure 3

Map of the Canadian distribution of the Gold-edged Gem, which extends from Spruce Woods Provincial Park in southwestern Manitoba, through southern Saskatchewan to southeastern Alberta. Occurrences are indicated by symbols; major dune areas are shaded.

As of 2015, Gold-edged Gem has been documented at 35 individual sand dunes and blowouts in 14 separate sand hillsFootnote1 (Figure 3, Table 1). These include four sand hills in Alberta, nine in Saskatchewan, and one in Manitoba. This increase from four known Canadian sites in 2006 is due to additional survey effort in 2008-2011 and 2015 (see Search Effort), rather than actual range expansion.

Table 1. Known Canadian occurrences of the Gold-edged Gem (GEG), Schinia avemensis.
Prov.Sand Hills (SH)Year First RecordedMost Recent Record# Dunes / Blowouts with GEGHighest Single Day # of GEG at a single dune or blowout
ABBowmanton SHa1939?200811
ABDune Point SH20042004115+
ABMiddle SH1939?201097
ABPakowki Lake SH20052012455+
SKAntelope SH2015201519
SKBurstall SH2004201512
SKCramersberg SH2009201117
SKDundurn SH2010201011
SKElbow SH2011201154
SKGreat SH2015201534
SKSeward SH2015201523
SKTunstall SH20052010411
SKWesterham SH2015201514
MBBrandon SH19032015138

Total number of Dunes / Blowouts with GEG = 35

a Bowmanton SH is sometimes pooled with Middle SH (e.g., Wolfe 2010; Environment Canada 2014).

In Alberta, Gold-edged Gems are known from eight dunes or blowouts in the Middle Sand Hills (SH) (Curteanu et al. 2011; Jensen 1999), four blowouts in the Pakowki Lake SH, as well as single sites within the Bowmanton SH (sometimes considered part of the Middle SH) and a blowout in the Dune Point SH near Blindloss. In Saskatchewan, they are known from multiple sites in the Elbow, Great, Seward, and Tunstall sand hills, as well as single dunes or blowouts in the Antelope, Burstall, Cramersburg, Dundurn, and Westerham sand hills. Gold-edged Gems have long been known from the Brandon Sand Hills in MB. They were collected from the Aweme area in the early 1900s, but have not been seen there in decades, likely due to loss of habitat from dune stabilization (COSEWIC 2006). They are now known only from eastern portion of the Brandon SH at Spirit Sands in Spruce Woods Provincial Park and adjacent areas of Canadian Forces Base (CFB) Shilo (Murray 2013; Environment Canada 2014; Murray and Church 2015).

Gold-edged Gems may occur at additional dunes and blowouts that have not yet been surveyed (see Search Effort). Most of the potential habitat is within the current Canadian extent of occurrence, but there are also unsurveyed sand hills outside the current known Canadian range (e.g., Pike Lake SH).

A species can be considered to be severely fragmented if most (>50%) of its total area of occupancy is in habitat patches that are (1) smaller than would be required to support a viable subpopulation, and (2) separated from other habitat patches by a large distance at a scale that is appropriate to the taxon under consideration. To evaluate severe fragmentation for Gold-edged Gem, each of the 14 sand hills were considered to be a habitat patch. To determine viability, a conservative scoring approach incorporated: Available open-sand habitat within the sand hill; Inferred habitat occupancy based on recorded occurrences and search effort; and expert opinion (Table 4). Of the total 14 sand hills or habitat patches, nine were considered not viable and only five were considered likely to support a viable subpopulation (Table 4). All habitat patches were considered separated by a large distance, relative to plausible dispersal distances for the Gold-edged Gem (Table 5). The total area of occupancy was calculated based on the number of index of area of occupancy (IAO) grid squares for the species at each habitat patch (Table 5). This resulted in 58% (18 out of 31 grid squares or 72 km2/ 124 km2) of its total area of occupancy in habitat patches that would not support a viable subpopulation and were separated by a distance considered too large for dispersal. Therefore, the Gold-edged Gem is considered to be severely fragmented in small, discrete areas of suitable dune habitat.

Extent of occurrence and area of occupancy

The extent of occurrence (EOO) in Canada is approximately 121,000 km2 using a minimum convex polygon encompassing all known sites in 2015, significantly larger than the EOO of 70,500 km2 from the 2006 COSEWIC assessment.

The current index of area of occupancy (IAO) is approximately 124 km2 (31 grid squares), based on a fixed 2 x 2 km grid.

Search effort

Gold-edged Gem was first discovered at Aweme, MB in 1903 (Dyer 1914), and museum specimens indicate sporadic collecting in the Aweme area (including Treesbank and Onah), through 1924 (COSEWIC 2006). A single specimen was collected in “Medicine Hat” in 1939 – the exact location is unknown, and it may have come from the nearby Burnstall or Middle sand hills. Four specimens were also collected in the Bald Head Hills (Spirit Dunes) north of Glenboro in 1958 (COSEWIC 2006). Until relatively recent surveys for the 2006 COSEWIC status report, search effort for Gold-edged Gems was largely undocumented, with museum specimens representing the only available evidence of successful surveys.

Table 2 summarizes recent targeted survey efforts for Gold-edged Gem in Canada. Documented surveys for Gold-edged Gem in Canada began in 2003 when J. Troubridge and J.D. Lafontaine visited the Spirit Dunes at Spruce Woods Provincial Park in the Brandon Sand Hills. In 2004, G. Anweiler conducted additional surveys at Spirit Sands in support of the 2006 COSEWC status report, as well as surveys elsewhere in the Brandon, Oak Lake, and Lauder sand hills. Anweiler also surveyed five other sites in Saskatchewan and Alberta, and found a single Gold-edged Gem in the Burstall SH on 6 August 2014, representing the first confirmed record for Saskatchewan. C. Schmidt found Gold-edged Gems at Dune Point Sand Hill (Empress Meander) along the Red Deer River north of Blindloss, AB in July 2014, and G. Anweiler discovered Gold-edged Gems in the Pakowki Lake SH in July 2005 (COSEWIC 2006).

Table 2. Summary of recent (post-2000) surveys and observations for the Gold-edged Gem in Canadab
ProvinceSand Hill (#)cYearSurvey Dates# of Dunes/ BlowoutsSurvey Effortd (hrs)# Flowerse Checked# Schinia ObservedObservers
ALBERTABowmanton SHf2008Aug 111--1G. Anweiler, M. Curteanu, O. Jensen
ALBERTABowmanton SHf2009Jul 27, Aug 1111.37490CWS
ALBERTABowmanton SHf2010Aug 4-610.86510CWS
ALBERTADominion SH2010Aug 2200.81930CWS
ALBERTADune Point SH (9)2004Jul 29-2.0-15+Schmidt
ALBERTADune Point SH (9)2015Jul 3041.15891CWS
ALBERTAEdgerton SH (1)2004Jul 29-10-0Schmidt
ALBERTAEdgerton SH (1)2011Aug 1310.31880CWS
ALBERTAMiddle SH2008Aug 11-126--4G. Anweiler, M. Curteanu, O. Jensen
ALBERTAMiddle SH2009Jul 211-100s1R. Dzenkiw
ALBERTAMiddle SH2009Jul 24-27, Aug 10-112223.919,5278CWS
ALBERTAMiddle SH2010Aug 4-693.01,25512CWS
ALBERTAPakowki Lake SH (10)2005Jul 21-4.0-~15G. Anweiler
ALBERTAPakowki Lake SH (10)2008Aug 101-->50G. Anweiler, M. Curteanu, O. Jensen
ALBERTAPakowki Lake SH (10)2009Jul 13---1G. Anweiler
ALBERTAPakowki Lake SH (10)2009Jul 2313.4-5CWS
ALBERTAPakowki Lake SH (10)2010Jul 14---3G. Anweiler
ALBERTAPakowki Lake SH (10)2010Jul 15, Aug 744.95,40787CWS
ALBERTAPakowki Lake SH (10)2012Jul 25---1J. Kitts
ALBERTAWainwright SH2010Jul 2783.91,9590CWS
ALBERTAWainwright SH2011Aug 1410.2g1,0750CWS
SASKATCHEWANAntelope SH2015Aug 522.72,2689R. Foster, A. Harris
SASKATCHEWANBairsay SH2011Aug 173--0CWS
SASKATCHEWANBattle River SH2010Jul 2972.31,0050CWS
SASKATCHEWANBig Stick SH2015Aug 431.41080R. Foster
SASKATCHEWANBorden SH (3)2004Jul 26-0.500G. Anweiler
SASKATCHEWANBurstall SH (8)2004Aug 8-2.0-1G. Anweiler
SASKATCHEWANBurstall SH (8)2015Jul 25-3082.12,1252CWS
SASKATCHEWANCramersburg SH2011Aug 6-752.33,3677CWS
SASKATCHEWANDundurn SH2010Aug 2-787.06,5151CWS
SASKATCHEWANDundurn SH2011Aug 4, 1770.51580CWS
SASKATCHEWANElbow SH2010Aug 10-1163.02,0390CWS
SASKATCHEWANElbow SH2011Aug 9-1194.33,1269CWS
SASKATCHEWANGood Spirit Lake (4)2004July 27-6.000G. Anweiler
SASKATCHEWANGreat SH (7)2004Aug 6-8.000G. Anweiler
SASKATCHEWANGreat SH (7)2015Aug 5-71718.87807R. Foster, A. Harris
SASKATCHEWANNorth Battleford SH (2)2004Jul 26-1.000G. Anweiler
SASKATCHEWANNorth Battleford SH (2)2011Aug 1220.1150CWS
SASKATCHEWANPiapot SH2015Aug 421.89740R. Foster
SASKATCHEWANSeward SH2015Aug 352.82154R. Foster
SASKATCHEWANTunstall SH2009Jul 187--1D. Bender
SASKATCHEWANTunstall SH2009Aug 8several--3G. Anweiler, W.Falk
SASKATCHEWANTunstall SH2010Aug 944.53,97120CWS
SASKATCHEWANWesterham SH2015Aug 614.72,8644R. Foster, A. Harris
MANITOBABrandon SH (6)2003Jul 27- 28,1--10J. Troubridge, J.D. LaFontaine
MANITOBABrandon SH (6)2003Aug 41--1+G. Anweiler
MANITOBABrandon SH (6)2003Aug 26-271--0G. Anweiler
MANITOBABrandon SH (6)2004Jul 27
Aug 4
112.0-7+G. Anweiler
MANITOBABrandon SH (6)2009Aug 1912.12,1134P. Gossen
MANITOBABrandon SH (6)2012Aug 81--25MB CDC
MANITOBABrandon SH (6)2012Aug 95--15MB CDC
MANITOBABrandon SH (6)2013Aug 145--38MB CDC
MANITOBABrandon SH (6)2013Aug 238--6MB CDC
MANITOBABrandon SH (6)2015Aug 811.83006R. Foster, A. Harris
MANITOBALauder SH and Oak Lake SH (5)2004Jul 28-
Aug 4
-12-0G. Anweiler
MANITOBALauder-Oak Lake-Souris-Carberry SH2009Jun 22-Aug 6<19--0MB CDC
MANITOBALauder-Oak Lake-Souris-Carberry SH2010-<32--0MB CDC
MANITOBALauder-Oak Lake-Souris-Carberry SH2011Jul-Aug 55--0MB CDC
MANITOBALauder-Oak Lake-Souris-Carberry SH2012-4--0MB CDC
MANITOBALauder-Oak Lake-Souris-Carberry SH2014-2--0MB CDC

b sand hill (SH) names follow Wolfe (2010); blank cells = unknown within 3rd-6th columns

c sand hill / site # from Table 1 of 2006 COSEWIC status report

d surveys in 2008 and 2015 focused on documenting presence/absence rather than total counts of individuals

e number of Prairie Sunflowers (Helianthus petiolaris) checked for Gold-edged Gem, if known.

f Curteanu et al. (2011), Wolfe (2010), Environment Canada (2014) included Dune 25 (Dugway) in Middle Sand Hills

g roadside only

Targeted surveys for Gold-edged Gems and other dune taxa were also conducted by the Canadian Wildlife Service (CWS) and partners in 2008-2011 in support of the national recovery strategy (Curteanu et al. 2011). A total of 84 active open sand dunes and blowouts were surveyed within 16 sites in 13 sand hills. Gold-edged Gems were documented at 22 sand dunes/blowouts including new subpopulations at Cramersburg, Dundurn, Elbow and Tunstall sand hills in Saskatchewan. Additional surveys were also conducted in 2015, confirming continued presence of Gold-edged Gems at Burstall and Dune Point sand hills (V. Snabel pers comm. 2015).

Targeted searches for Gold-edged Gems were conducted in the Brandon, Carberry, Lauder, Oak Lake, and Souris sand hills from 2009-2014 by Manitoba Conservation Data Centre (CDC) staff (Friesen and Murray 2010, 2011; Murray and Friesen 2012; Murray 2013, 2014; Murray and Church 2015). Apart from Spirit Sands and adjacent CFB Shilo, no Gold-edged Gems were found during these surveys. Field observations and the examination of satellite imagery indicates that only very small (typically <1 ha) pockets of suitable habitat remain due to dune stabilization.

In support of this COSEWIC report, a total of 34 survey-hours were conducted at 12 sites from August 3-8, 2015 in southwestern Saskatchewan and Spirit Sands by R. Foster and A. Harris (Northern Bioscience). Gold-edged Gems were confirmed at seven dunes or blowouts at four sand hills where they had not previously been recorded (Antelope, Seward, Great, Westerham).

Analysis of survey effort to date (Table 3) using a recent inventory of dunes and blowouts in the sand hills of the Canadian Prairie provinces (Wolfe 2010) suggests that the majority of potential habitat has never been surveyed. Of the approximately 481 dunes and blowouts (621 ha) mapped within the known range of Gold-edged Gem, only 85 dunes/blowouts (173 ha) have been surveyed to date, with Gold-edged Gems confirmed from 27 (97 ha). Approximately 70% of the dunes and blowouts previously surveyed have had Prairie Sunflower present, suggesting that a relatively high proportion of remaining unsurveyed bare sand areas is potentially suitable for the Gold-edged Gem. In addition, Gold-edged Gems may be present but missed at some of the previously surveyed habitat due to the flight period or diel activity of the moths (see Abundance).

Table 3. Number of mapped (Wolfe 2010) dunes and blowouts within the known Canadian range (i.e., expected range based on geographic proximity) of Gold-edged Gem (GEG) in relation to past survey efforth
ProvinceSand Hill (SH)Total Sand Hill Area (ha)Dune/ Blowouts Surveyed for Gold-edged Gem
Total # with GEG
Dune/ Blowouts Surveyed for Gold-edged Gem
Total # Surveyed
Dune/ Blowouts Surveyed for Gold-edged Gem
Total Area (ha) Surveyed
-Total
# Dunes / Blowouts
Total
Area of Bare Sand (ha)
ALBERTABowmanton SHi24,844110.120.1
ALBERTADominion SH1,779-----
ALBERTADune Point SHj509145.345.3
ALBERTAEmpress Meander SHj1,716---37.8
ALBERTAHilda SH5,436-----
ALBERTAMiddle SH32,519482.0183.4
ALBERTAPakowki Lake SH4,984448.05623.6
SASKATCHEWANAntelope SHk6,839110.610.6
SASKATCHEWANBig Stick SHl21,962-410.01817.6
SASKATCHEWANBirsay SH9,668-30.652.2
SASKATCHEWANBurstall SH15,3641715.41523.6
SASKATCHEWANCrane Lake SHl13,885---10.6
SASKATCHEWANCarmichael SH3,932-----
SASKATCHEWANCramersburg SH18,965152.21911.7
SASKATCHEWANDundurn SH30,683182.22315.3
SASKATCHEWANElbow SH18,03751543.66062.8
SASKATCHEWANGreat SH112,66211230.6201303.3
SASKATCHEWANPelican Lake SH7,247---40.6
SASKATCHEWANPiapot SH7,384-23.123.1
SASKATCHEWANPike Lake SH29,125-----
SASKATCHEWANSeward SH10,7542512.41323.5
SASKATCHEWANTunstall SH5,8273410.61733.5
SASKATCHEWANWesterham3,950111.321.7
MANITOBABrandon SH144,5741125.0678.0
MANITOBALauder SH12,337---112.2
MANITOBAOak Lake SH4,108-----
MANITOBARoutledge SH1,549-----
MANITOBASouris SH1,898-----
MANITOBASt. Lazare SH6,186-----
TOTAL-558,7222785172.8481620.5

h additional dunes and blowouts not mapped by Wolfe (2010) have been surveyed, six of which had Gold-edged Gem.

i Bowmanton SH is sometimes pooled with Middle SH (e.g., Wolfe 2010).

j Dune Point and Empress meander are sometimes pooled (e.g., Environment Canada 2014, Table 1), but are separate sand hills.

k Antelope SH are pooled with Seward SH in Wolfe (2010).

l Bigstick and Crane sand hills are sometimes pooled together as Bigstick-Crane Lake SH.

Table 4. Viability within each habitat patch for Gold-edged gem (e.g., is a habitat patch smaller than what would be required to support a viable population?). A = Available open-sand habitat (D/BO = dunes or blowouts) within the SH. B = Inferred habitat occupancy based on recorded occurrences and search effort.
ABViabilityConsiderationsHabitat PatchViability Score
LowLowNon-viable
  • Very low # D/BO (<=5)
Dune Point
Westerham
Antelope
Not viable
LowLowNon-viable
  • Fairly low # D/BO (6-20)
  • Infer low occupancy from search effort and detected occurrences
Burstall
Cramersburg
Seward
Not viable
HighHighViable
  • >20 D/BO
  • Search effort & detected occurrences suggest that occupancy could be high
Pakowki ElbowViable
LowHighViable or premature to consider as non-viable
  • Fairly low # D/BO (6-20)
  • Search effort & detected occurrences suggest that occupancy could be high
TunstallViable
HighLowDiscretion needed
  • >20 D/BO
  • Infer low occupancy from search effort and detected occurrences
DundurnNot viable
HighLowDiscretion needed
  • >20 D/BO including large established dunes
  • Large numbers of individuals observed
BrandonViable
HighLowDiscretion needed
  • >20 D/BO, but of very small size
  • Fairly large number of occurrences, but with very low numbers of individuals
Middle and BowmantonNot viable
HighUnknPremature to consider as non-viable
  • >20 D/BO including large established dunes
  • Search effort preliminary, some occurrences found
GreatViable
Table 5. Number of index of area of occupancy (IAO) 2x2 km2 grid squares for Sand Hills. 18 of 31 grid squares (58%) are from sand hills considered not viable within Table 4.
Prov.Sand Hills (SH)# of IAO
2 x 2 km squares
Viable?Distance from nearest
occupied SH
ABBowmanton SH1Not Viable~29 km
ABDune Point SH1Not Viable~29 km
ABMiddle SH8Not Viable~29 km
ABPakowki Lake SH1Viable~120 km
SKAntelope SH1Not Viable~15 km
SKBurstall SH1Not Viable~30 km
SKCramersberg SH2Not Viable~50 km
SKDundurn SH1Not Viable~83 km
SKElbow SH4Viable~83 km
SKGreat SH3Viable~50 km
SKSeward SH2Not Viable~15 km
SKTunstall SH4Viable~63 km
SKWesterham SH1Not Viable~30 km
MBBrandon SH1Viable~530 km
TOTAL-31--

Most of the easily accessible higher quality habitat has been surveyed, but approximately 450 ha of bare sand habitat remains unsurveyed within the known Canadian range of the Gold-edged Gem. In particular, no surveys have yet been conducted in the Empress, Harris, Hilda, Pelican Lake, Pike Lake, Carmichael, and Crane sand hills, and there remain many unsurveyed dunes and blowouts within the Great SH (>300 ha total), as well lesser amounts in other previously surveyed sand hills within the known range (Table 3). There are also other unsurveyed sand hills in the southern Prairies outside the known range of Gold-edged Gem, such as Duchess, Grassy Lake, and Rolling Hills Lake sand hills in Alberta, that might have small pockets of suitable habitat.

There appears to have been little targeted effort in the United States except at Great Sand Dunes National Monument. C. Harp has recently begun checking potentially suitable habitat between US and Canadian occurrences, including the Seminoe and Kilpecker dunes in Wyoming (Harp pers. comm. 2015).


Habitat

Habitat requirements

Gold-edged Gems appear to be obligate dune specialists within the range of the presumed host plant, Prairie Sunflower (Helianthus petiolaris). In Canada, these are typically glaciofluvial or glaciodeltaic sand deposits that have been reworked into dunes by wind at varying times throughout the Holocene (Wolfe 2002, 2010). Gold-edged Gems have only been found in or immediately adjacent to open, barren or sparsely vegetated sand dunes, sand flats, or sandy hill areas that are actively eroding and being moved by wind (COSEWIC 2006; Environment Canada 2014). These active sand dunes and blowouts currently occur as isolated patches on the crests of partially or fully stabilized sand dunes that are scattered within a landscape that now supports prairie grassland (David 1977; Wolfe 1997, 2010). Suitable habitat for Gold-edged Gems is thus extremely fragmented and patchy. The largest active dunes in Canada with known Gold-edged Gem subpopulations are Dune #429 (40 ha) in the Elbow SH and Dune #171 (25 ha) in the Brandon SH (dune identification follows Wolfe 2010), but most Canadian subpopulations are in much smaller (<1 ha) dunes or blowouts.

Prairie Sunflowers occur along the margins of many active dunes and blowouts, and may grow in the centre of the blowout as well (COSEWIC 2006; Environment Canada 2014; Foster and Harris pers. obs.). They may be sparsely scattered along the edge of the dune (Figure 4) or in dense patches numbering thousands of individuals (Figure 5). Active dunes may also lack both Gold-edged Gems and Prairie Sunflowers, possibly due to factors such as topography and moisture (i.e., ridges and swales vs. extensive level sand sheets) and differences in sand particle size (COSEWIC 2006). Prairie Sunflowers are often lacking from large, sheet-like dunes with little topographic relief such as those in the Burstall SH, Great SH south of Sceptre (Prelate) and Portreeve (Figure 6), and the Big Stick SH where the vegetation is very sparse and consists primarily of Scurf-pea (Psoralea lanceolatum) and Sand Dock (Rumex venosus), with Prairie Sunflower restricted to scattered individuals along the margins or in adjacent grasslands or roadsides (COSEWIC 2006; Foster and Harris pers. obs.). At the Spirit Dunes site in the Brandon SH, Prairie Sunflowers occurred in essentially pure stands as an early pioneer on active sand above and below the active dune crests, where they were rarely observed growing mixed with other dune vegetation, with the exception of Sand Dock at some sites (COSEWIC 2006). Prairie Sunflower is also found at the Colorado sites (Opler pers. comm. 2015), as it is found native throughout much of the Great Plains and adventive elsewhere (Schilling 2006).

Figure 4. Gold-edged Gem habitat with sparse Prairie Sunflowers along leading margin of active sand dune in the Great Sand Hills east of Fox Valley (SK), 7 August 2015. See Figure 8 for GoogleEarth imagery of this site.
Photo of Gold-edged Gem habitat (see long description below)
Long description for Figure 4

Photo of Gold-edged Gem habitat with sparse Prairie Sunflowers along the leading margin of an active sand dune in the Great Sand Hills east of Fox Valley, Saskatchewan.

Figure 5. Gold-edged Gem habitat at Antelope Sand Hills (SK) blowout with abundant Prairie Sunflowers, 5 August 2015.
Gold-edged Gem Habitat (see long description below)
Long description for Figure 5

Photo of Gold-edged Gem habitat at an Antelope Sand Hills, Saskatchewan, blowout with abundant Prairie Sunflowers.

Figure 6. Extensive sand dune with sparse vegetation and ATV tracks in the Great Sand Hills south of Portreeve (SK). Approximately 20 Prairie Sunflowers (arrow) but no Gold-edged Gem were observed on 5 August 2015.
Dunes with vegetation (see long description below)
Long description for Figure 6

Photo of extensive sand dune with sparse vegetation and all-terrain vehicle tracks in the Great Sand Hills south of Portreeve, Saskatchewan. An arrow indicates the location of a patch of Prairie Sunflowers.

Prairie Sunflower is an early colonizer of disturbed habitats (Moss 1994), and is widespread and abundant along sandy roadsides, fallow fields, and other open areas in the southern Prairie provinces (Looman and Best 1979; COSEWIC 2006; Foster pers. obs). However, Gold-edged Gems have not been observed in anthropogenic habitats such as roadsides, suggesting that the species does indeed require the natural active sand dune areas where it has been found (Environment Canada 2014).

Gold-edged Gems were recently observed (Foster pers. obs.) in atypical habitat in the Great Sand Hills east of Fox Valley that was about 1 km from the nearest active dune or blowout (Figure 8). Two adults were observed in a patch of approximately 160 sunflowers spread along 40 m of a low (approximate 10 m height), southeast-facing slope. The slope was fairly stable but sparsely vegetated and had areas of bare, sandy soil where it had been disturbed by several cattle trails along its face (Figure 7). The site was approximately 1 km west of the nearest blowout (Blowout #482, Wolfe 2010) where four other Gold-edged Gems were observed. It is not known if Gold-edged Gems are able to complete their life cycle at this site, or if it represents a population sink. In 2009, a lone Gold-edged Gem was observed by R. Dzenkiw in atypical habitat on the actively eroding crest of a southeast-facing slope overlooking the South Saskatchewan River (Bender pers. comm. 2009). The steep slope and wind erosion have maintained open patches of bare sand at this site, which is approximately 1 km from the nearest occupied blowout in the Middle SH.

Figure 7. Slope with Prairie Sunflowers and Gold-edged Gems that was disturbed by cattle tracks in the Great Sand Hills east of Fox Valley (SK), 7 August 2015. See Figure 8 for GoogleEarth imagery of this site.
Photo of a slope containing Prairie Sunflowers (see long description below)
Long description for Figure 7

Photo of a slope containing Prairie Sunflowers and Gold-edged Gems that shows disturbance by cattle (tracks) in the Great Sand Hills east of Fox Valley, Saskatchewan.

Figure 8. Comparison of two separate sites where Gold-edged Gems were observed (yellow arrows) in atypical habitat along a slope eroded by cattle trails (upper GoogleEarth image) and more typical dune habitat (lower image, same scale) 1.5 km away on August 7, 2016 in the Great Sand Hills near Fox Valley. See Figures 4 and 7 for photos of these sites.
Two GoogleEarth images enabling comparison of two sites (see long description below)
Long description for Figure 8

Two GoogleEarth images enabling comparison of two sites where Gold-edged Gems were observed in atypical habitat along a slope eroded by cattle trails (upper image) and in more typical dune habitat (lower image) 1.5 kilometres away in the Great Sand Hills near Fox Valley, Saskatchewan.

As the early life stages of the Gold-edged Gem have not been documented (see Biology), the reasons why Gold-edged Gems appear to be dependent on active sand dunes or blowouts are unknown. The sand substrate may offer a humid and stable microclimate during the vulnerable pupal stage, and may facilitate the burrowing activity during the larval and adult emergence stage. The depauperate fauna of the dune habitat may also provide a more secure environment with a lower risk of predation or parasitism.

A suitable nectar source for adults is also an important habitat element. Prairie Sunflowers and Rush Skeletonplant (Lygodesmia juncea) are the primary nectar sources for Gold-edged Gem (COSEWIC 2006; Curteanu et al. 2011; Harp pers. comm. 2015). Rush Skeletonplant (also known as Common Skeletonweed) is a widely distributed perennial in the Great Plains and is found at most Canadian Gold-edged Gem occurrences, where it typically begins to flower earlier than Prairie Sunflower. Gold-edged Gems have also been observed perching on Rhombic-leaved Sunflowers (Helianthus pauciflorussubsp. subrhomboideus) in the Middle Sand Hills; however, they have never been observed mating or feeding on Rhombic-leaved Sunflowers (Curteanu et al. 2011; Environment Canada 2014).

Habitat trends

Trends in Gold-edged Gem habitat in Canada are driven by the patterns of dune activity and stabilization in the southern Prairies. These dune systems are derived from sandy deposits left behind by the receding Laurentide Ice Sheet and reworked by aeolian and other processes (Hugenholtz et al. 2010). These dunes therefore evolved from a finite sand supply and represent a closed sedimentary system; as such, the main controls on dune activity in this region are variations in climatic and biological or anthropogenic factors that control sediment availability and/or transport capacity (Muhs and Wolfe 1999; Hugenholtz and Wolfe 2005b). Stratigraphic and chronological studies (e.g., Dean et al. 1996; Muhs et al. 1997a,b; Wolfe et al. 2002, 2004, 2006) document a history of alternating periods of dune activity and stability across the Prairies during the last 10,000 years. For example, in southwestern Manitoba, there were at least six alternating periods of dune activity and stabilization in the past 5000 years (David 1971; Wolfe et al. 2000; Havholm and Running 2005), and in the Great SH there was widespread dune activity in the 1800s, in response to reduced precipitation in the late 1700s (Wolfe et al. 2001). Accounts of Dominion land surveyors (e.g., Hind 1859) and explorers (e.g., Palliser 1862) also provide evidence of extensive active sand dunes at the Elbow and Middle sand hills in the mid-1800s (Muhs and Holliday 1995; Wolfe et al. 2007; Hugenholtz et al. 2010). Following an active period of approximately 80 years during the 1800s, the sand hills in the Canadian Prairies have been slowly stabilizing, despite periodic drought intervals (Wolfe et al. 2001). Although regional climate is the primary driver, widespread irrigation, the extirpation of Bison (Bos bison) herds, and the suppression of fires have also been cited as factors contributing to dune stabilization in the 1900s (Wolfe and Nickling 1997; Forman et al. 2001; Hugenholtz et al. 2010). Grazing, trailing, wallowing, horning, and trampling by Bison helped create and maintain a patchy disturbance mosaic in the sand hills of the southern Canadian prairies; the beneficial effects of which could potentially be re-established by the reintroduction of Bison (Fox et al. 2012).

Archival aerial photographs and satellite imagery document widespread dune stabilization across the southern Canadian prairies since the early 1900s (Hugenholtz and Wolfe 2005a; Wolfe et al. 2007). These changes represent a decrease of wind erosion and dune mobility by progressive increase of vegetation cover (Hugenholtz et al. 2010). Many active dunes have been stabilized by vegetation at a rate of 10-40% per decade, and less than 1% of the sand hill area in the Canadian prairies is currently active with bare sand (Wolfe 2001, 2010). The most dramatic changes occurred in the Middle SH where the area of open sand decreased by 94% between 1947 and 2005, and at a compound dune in the Brandon SH where the area of open sand decreased by 95% between 1928 and 2006 (Hugenholtz et al. 2010). At six other sites, most of which have Gold-edged Gem subpopulations, the area of open sand decreased by 21–53% (Figure 9). The combined loss of open sand at these eight sites between 1970 and 2006 is 47%, which is equivalent to the loss of 330 ha in 36 years or 9 ha/year (Hugenholtz et al. 2010). The loss of area at larger dunes such as at Elbow SH (Wolfe et al. 2007) also reduces the dune perimeter, which likely reduces the zone of suitable habitat for Gold-edged Gem along the sparsely vegetated periphery where Prairie Sunflowers are most abundant.

Figure 9. Historical trends of dune stabilization at eight sand hills with Gold-edged Gem subpopulations (Hugenholtz et al. 2010).
Chart illustrating historical trends (see long description below)
Long description for Figure 9

Chart illustrating historical trends in dune stabilization at eight sand hills supporting Gold-edged Gem subpopulations.

Many smaller sand hills with minor levels of dune activity in the mid-1900s now sustain only small pockets of active sand (Hugenholtz et al. 2010). Sheet-like barchan dunes and interdunal areas nearly devoid of vegetation have been transformed over the past 200 years into parabolic dunes whose form is controlled by vegetation (Wolfe and David 1997; Wolfe and Hugenholtz 2009). Blowouts are now the most pervasive active aeolian landform on the Canadian prairies (Hugenholtz and Wolfe 2006), providing small discrete patches of open-sand habitat within mostly stabilized dune fields (Hugenholtz et al. 2010).

Although climate explains a significant portion of the historical trend towards dune stabilization at a regional scale, disturbance accounts for the persistence of some active dunes and blowouts in areas that are otherwise stabilized by vegetation (Hugenholtz et al. 2010). Fire, cultivation, logging, off-road vehicle traffic and livestock grazing can increase or restore dune activity and lead to the development of new generations of dunes (Hugenholtz et al. 2010). Blowouts develop when a localized disturbance produces a breach in the vegetation cover, thus enabling deflation by wind (Wolfe and Nickling 1997). Vegetation growth is inhibited where high wind stress and low moisture availability prevail, such as windward and south-facing slopes (Hugenholtz and Wolfe 2005b). The process of dune stabilization tends not to be a linear function of time, with stabilization slowing and following a negative exponential function in later stages (Hugenholtz and Wolfe 2005b). This might account for the persistence of some base level of dune activity (Wolfe et al. 2007).

In addition to habitat loss, dune stabilization results in a more fragmented habitat as active dune areas shrink and disappear, likely with negative impacts on Gold-edged Gem metapopulation dynamics. Under these dynamics, even a small loss of habitat, such as a centrally placed dune, can significantly reduce subpopulation persistence (e.g., see Bascompte and Soulé 1996), especially if dispersal among sand dunes is disrupted by the loss of a ‘stepping-stone’ habitat patch (Hugenholtz et al. 2010; see Dispersal and Migration; Canadian Range).

Although dune activity is expected to continue to decline in the coming decades under the present climate and disturbance regimes (Wolfe 2010), dunes are extremely sensitive to climatic variability and the potential for reactivation is high (Muhs and Holliday 1995). If recent projections of climate warming and increased aridity hold true, there is the potential for increased dune activity particularly near the centre of the Palliser Triangle in the Great Sand Hills (Wolfe and Hugenholtz 2009). Although regional reactivation of sand dunes may require several decades (Wolfe 1997; Wolfe et al. 2001), this would eventually result in an increasing amount of suitable habitat for Gold-edged Gem if subpopulations remain nearby to recolonize it.


Biology

Life cycle, demographic parameters and reproduction

Like all Lepidoptera, Gold-edged Gems undergo complete metamorphosis with egg, larval, pupal and adult stages. The early life stages are not known to have been observed and only the adults have been described (Hardwick 1996). Based on observations of adults, Gold-edged Gems are univoltine, with one brood or cycle per year. Adults have been collected in Canada from July 10 to August 23 (Table 2; COSEWIC 2006). Field observations indicate that adults first emerge as the first of the Prairie Sunflowers bloom in mid-July or early August, with the flight period ending in late August while sunflowers are still in full bloom (COSEWIC 2006; Curteanu et al. 2011; Environment Canada 2014). All adult flower moths (Heliothines) are apparently short-lived; in laboratory rearings, none lived for more than a week (Hardwick 1996). The Gold-edged Gem flight period therefore represents sequential observations of multiple individuals. Unlike most other sunflowers, Prairie Sunflower is an annual and is one of the last species of sunflowers to blossom. At Spirit Sands, Gold-edged Gems have been observed mating while perched on Prairie Sunflowers between July 28 (2004) and August 14 (2013)(COSEWIC 2006; MB CDC unpublished data).

Adult Gold-edged Gems are diurnal and are commonly observed perching on Prairie Sunflowers or Rush Skeletonplant from early morning until evening (e.g., Curteanu et al. 2011). At Spirit Sands, they have been observed perched on sunflowers on the dune face in the early morning (COSEWIC 2006), and were observed in August 2015 as late as 18:30 in the Seward and Antelope sand hills when air temperatures remained warm (24°C)(Foster pers. obs). A Gold-edged Gem was observed perching on a Prairie Sunflower at night (23:34, July 21) by R. Dzenkiw (Bender pers. comm. 2009). Diel activity patterns are at least partly dependent on ambient temperature and weather. Gold-edged Gems were not observed at the Westerham SH at 11:00 on 6 August 2015 when it was 11°C, windy and light rain, but they were active later in the day (15:30) when the skies had cleared and temperatures were 18°C (Foster and Harris pers. obs.). In contrast, during four years of observations at the Great Sand Dunes in Colorado, C. Harp (pers. comm. 2015), found Gold-edged Gems to be most active and common from 6:00 to 8:30, but they seemed to take cover around 9:00 as temperatures rose and other insects and birds became more active.

Early life stages of the Gold-edged Gem have not yet been described. All other species of Schinia studied by Hardwick (1996) deposit eggs in or on the flowering heads of their host plant. The ovipositors of Gold-edged Gems have the hard, knife-like, modified lobes found in species that insert their eggs downward among the florets of flowers in the family Asteraceae (Compositae), to which Prairie Sunflowers belong. Hardwick (1996) states unequivocally that in Manitoba Schinia avemensis “feed as larvae in the heads of Helianthus petiolaris…”, but provides no further details.

Schinia eggs hatch within a few days, and the larvae feed on or within the blossom, on the floral parts, and in some instances on the developing seeds of the host plant. Young larvae of some species have very specialized feeding habits, selecting a particular part of the floral structure, such as the anthers or the receptacle. Species feeding on composites usually feed first within the corolla tubes. The larvae of Schinia complete development within two to four weeks, depending on species. Species feeding on annuals (as do Gold-edged Gems) develop faster than those feeding on perennials, in some cases in less than 14 days (Hardwick 1996).

When fully developed, Schinialarvae leave the plant, burrow into the soil, and form a cell in which they pupate. They remain in the pupal stage through the winter and spring, emerging to mate and reproduce when the host plant blooms the following summer (Hardwick 1996). A number of species of Schinia are able to remain in the pupal stage for more than one year, an adaptation to life in xeric habitats where conditions may not be suitable for the host plants to blossom each year (Hardwick 1996).

Physiology and adaptability

Dependency on a narrow range of host plants is usual in the genus Schinia, with many individual Schinia species restricted to one or several host plant species in a single genus, or to a few closely related genera of host plants (Hardwick 1996).

Members of the genus Schinia, and in particular the composite flower-feeding desert species, are capable of remaining in pupal diapause for extended (multi-year) periods, an adaptation to an environment where seasonal cycles of rainfall and plant blossoming can be unpredictable (Hardwick 1996). Because Prairie Sunflower is an annual, its abundance may have greater variability among years and Gold-edged Gems may have the ability to extend the pupal stage depending on environmental conditions (e.g., drought).

Monophagous lepidoptera (i.e., species that feed on a single plant species) have to be selective in choosing plants for oviposition as the timing of larval development must coincide with that of the host plant (Dempster 1997; Peterson 1997). Starvation caused by the larvae’s inability to consume the hard coated seed pods due to late oviposition and development has been reported as a cause of mortality in some butterfly species (Dempster 1997). Gold-edged Gem could potentially suffer higher mortality rates and lower reproductive success if adult emergence, oviposition, and larval hatching do not coincide with larval host plant blossoming and seed development (Environment Canada 2014).

Dispersal and migration

Gold-edged Gems are not known to undergo any regular migrations or dispersal events but are active fliers (COSEWIC 2006; Foster pers. obs.). Many species of Schinia are strong fliers and adept at colonizing successional habitats or coping with plants that do not flower every year (Schweitzer 2001 in NatureServe 2015). They often reach high densities and can colonize small patches of plants if there are other source patches in the area. While straying does occur, adults concentrate near their larval food plant (Schweitzer 2001 in NatureServe 2015).

According to NatureServe (2015), for Schinia species all occupied habitat patches within 10 km of each other should be considered a single metapopulation if the intervening landscape is suitable habitat, with 2 km used as the threshold separation distance for unsuitable habitat. Stabilized dune fields with occasional sunflowers (as on cattle trails) appear to be suitable dispersal habitat for Gold-edged Gem. The recent discovery of two Gold-edged Gems on a recently disturbed sandy slope in the Great Sand Hills (Figure 7) suggests that they can disperse at least 1 km from existing occurrences. Given the site characteristics, it is unlikely that the occupied patch of habitat is a relict subpopulation resulting from gradual stabilization, rather than a dispersal event to newly created, potentially suitable habitat that was also colonized by Prairie Sunflowers (Foster pers. obs.). It is therefore probable that Gold-edged Gems can disperse between active dunes or blowouts that are within 1-2 km of each other, as suggested by NatureServe (2015).

Similar inter-dune dispersal among habitat patches within large dunes is likely at some other sand hills (e.g., Elbow SH, Brandon SH) that have multiple known occurrences in close proximity. For example, at the fairly well-surveyed Middle SH (Jensen et al. 2009; Curteanu et al. 2011), blowouts with Gold-edged Gems are on average within 2.4 km from the nearest occupied blowout. In contrast, seven other Canadian sand hills have only single known Gold-edged Gem sites and few (if any) other suitable dunes or blowouts in the surrounding landscapes. In many cases, distances to the nearest suitable habitat or subpopulation may be prohibitive for successful dispersal. For instance, the 6839 ha Antelope SH are now almost completely stabilized and the only natural exposed sand area at least 0.5 ha in size is Blowout #759, where nine Gold-edged Gems were observed in 2015. This blowout is now 15 km from the nearest bare dune area of equal size, Blowout #756 in the Seward SH (which also has a subpopulation of Gold-edged Gems).

Interspecific interactions

Gold-edged Gems are believed to be dependent upon a single species, the Prairie Sunflower, for the larval host. Prairie Sunflower and Rush Skeletonplant are primary nectar sources for adults.

Other interspecific interactions for Gold-edged Gems are undocumented. Like most Lepidoptera, Gold-edged Gems are undoubtedly subject to competition, predation and parasitism by a variety of insects, birds, and other animals during all life stages. During the early larval stages, both inter- and intra-specific cannibalism is a common phenomenon among species of Schinia feeding on composites (Hardwick 1996). During 2015 surveys, a range of insects were observed on Prairie Sunflower inflorescences including ants, flower longhorn beetles, and a variety of wasp and bee pollinators (Foster pers. obs.).

Herbivory of the host plant by both wild and domesticated ungulates could result in the destruction of both the host and any larvae feeding therein. The flowering heads of Prairie Sunflowers are palatable to both wild and domestic ungulates, and significant local mortality of larvae could occur during periods of drought when more desirable alternate forage is in short supply, or in overgrazed ranges (COSEWIC 2006; Environment Canada 2014). Prairie Sunflowers in the Middle Sand Hills have been browsed by either Elk (Cervus elaphus) or possibly Mule Deer (Odocoileus hemionus) (Curteanu pers. comm. 2015).


Population sizes and trends

Sampling effort and methods

Approximately 85 dunes and blowouts have been surveyed within the known Canadian range of Gold-edged Gem during the flight season (see Search Effort). Surveys have typically focused on searching the flowers of the presumed host Prairie Sunflowers for adults or larvae, and opportunistically on other nearby flowering plants (e.g., Rush Skeletonplant) that may be used for nectaring. Many of the surveys prior to 2009 recorded presence/absence but not number of sunflowers checked or the time spent at each dune (COSEWIC 2006; Curteanu pers. comm. 2015). More recent surveys recorded the number of sunflowers checked for Gold-edged Gem to better describe survey effort and host plant abundance. In 2009, CWS staff did repeat visits to individual dunes in the Middle and Bowmanton sand hills to ensure that surveys were done during the actual flight period (Curteanu et al. 2011), but in other years single visits were often made in order to expand the search effort to more dunes. Because Gold-edged Gems are diurnal, light traps have not been used, but they do occasionally catch Gold-edged Gems if left out during daylight hours in suitable habitat.

The timing of Gold-edged Gem surveys is critical for detecting their presence at a site. The flight period is brief and variable among years, generally overlapping the period when Prairie Sunflowers begin to bloom. For example, intensive surveys of the Spirit Dunes on 28 July 2003 failed to detect any adult Gold-edged Gems when sunflowers were all in bud due to the lateness of the season (COSEWIC 2006). However, the moths were abundant a week later (August 4) when approximately 1/4 of the sunflower had bloomed, but none were observed on August 26-27 when the sunflowers were in full blossom and the flight period was apparently over.

It is possible to overlook Gold-edged Gems during the flight season due to diel activity patterns or other factors. For example, on the 7 August 2010, CWS personnel visited Pakowki Lake Sand Hills and spent from 11:00-17:14 surveying over 5000 sunflowers and finding over 90 Gold-edged Gems. Surveys the following morning at 10:00 at the same location failed to detect any Gold-edged Gems (Curteanu pers. comm. 2015).

Abundance

There are no reliable estimates for total Gold-edged Gem abundance in Canada. At least 300 Gold-edged Gems have been observed in the last 15 years in Canada, with an additional 30 or so specimens collected from 1903 to the 1960s (COSEWIC 2006; Curteanu et al. 2011; Environment Canada 2014; Foster unpublished data). However, there are no quantitative data available on population sizes for Gold-edged Gems nationally or at individual sites. More fieldwork is required to determine how many dunes and blowouts are occupied in Canada, and how many Gold-edged Gems occur in these habitats.

The focus of most surveys has not been total counts, and no mark-recapture studies have been conducted to estimate population size for this species. Sequential visits at individual sites during the same flight season have generally been lacking, so the number of individuals observed on any single visit likely represent only a fraction of the subpopulation at that site. Obtaining meaningful population estimates even in known occupied habitat is complicated by the small size and mobility of adult moths, as well as changes in numbers over the course of the day, the adult emergence period, and year to year variability. Subpopulation sizes of many moth species vary greatly from year to year due to weather and other factors (Pohl et al. 2004). Furthermore, the total number of occupied habitat patches in Canada is unknown, because less than 1/3 of potentially suitable habitat has been surveyed.

The most closely monitored subpopulation of Gold-edged Gem are at Spirit Sands (Spruce Woods Provincial Park) in the Brandon Sand Hills, where they have been surveyed in at least six separate years since 2003 (albeit with varying levels of effort). The highest total number observed in this subpopulation on one day was 38 Gold-edged Gems on 14th August 2013 in an area of approximately 50 ha (MB CDC unpublished data). This is equivalent to a density of approximately 0.8 moths per ha. The occupied area at the Spirit Sands was about 50 ha in 2004 (COSEWIC 2006). Despite the evident difficulties in estimating numbers of such a patchily distributed, fast-flying moth, COSEWIC (2006) suggested that a reasonable estimate of 10-50 adults per ha, or a total 500-2500 adults in 2004. In comparison, nine Gold-edged Gems were found in 2015 in a 1 ha blowout in the Antelope Sand Hills (Dune #759). The actual density is likely higher because only about 1100 of the estimated 6000 sunflowers present were searched due to time constraints, and there were likely many more Gold-edged Gems present. This suggests that the speculated density of 10-50 Gold-edged Gems per hectare (COSEWIC 2006) may be reasonable for high quality habitat. During the Gold-edged Gem flight period at the Great Sand Dunes National Monument in Colorado, in the early morning, 8-12 pairs could often be seen within an 8 m circle from a suitable spot at one time during the early morning (Harp pers. comm. 2015).

Despite unequal survey effort among sites, Pakowki Lake SH appears to have the largest known Gold-edged Gem subpopulation outside Manitoba based on recent survey counts (Curteanu et al. 2011; M. Curteanu pers. comm. 2015). An August 10, 2010 survey found 55 Gold-edged gems during an 84-minute survey of more than 2000 sunflowers at 5.3 ha Blowout #66, with additional sunflowers remaining unchecked. Smaller numbers (5 to 14) of Gold-edged Gems have also been found at three other smaller (0.3 to 2.1 ha) blowouts that have been checked in the Pakowki Lake SH, and there remain 52 dunes or blowouts (15.7 ha total) that have not yet been surveyed there. If the approximate density of 10 moths/ha observed at Blowout #66 is representative elsewhere, there may be approximately 200 Gold-edged Gems at Pakowki Lake. This is within the range of 100-500 Gold-edged Gems estimated for Pakowki Lake in COSEWIC (2006). Although the unsurveyed dunes at Pakowki Lake sand hills may be lower quality habitat with fewer sunflowers, the total observed at Blowout #66 represents a single day, point-in-time sample, and does not include other individuals active earlier or later during that year’s flight period, and so should be considered a minimum count.

Fluctuations and trends

Although there are few data with which to calculate population trend, the progressive stabilization and loss of active dune complexes in Canada during the past 100 years (Wolfe et al. 2000) has likely resulted in a corresponding reduction in the size and number of Gold-edged Gem subpopulations during that period. Gold-edged Gems have persisted at the Brandon SH in Manitoba for at least 100 years, but they are no longer found in the Aweme area due to dune stabilization. They have also persisted at Middle Sand Hills since at least 1939, but must be less abundant now given that bare sand areas in the Middle SH have decreased by 94% over the past 60 years (Hugenholtz et al. 2010).

The number of Prairie Sunflowers at some Canadian occurrences has been observed to vary greatly from year to year (Environment Canada 2014), potentially affecting Gold-edged Gem abundance at those sites. However, very little is known about the ecology of the Prairie Sunflower or how environmental and climatic conditions influence this plant’s distribution and germination and ultimately Gold-edged Gem subpopulations (Environment Canada 2014).

Rescue effect

Canadian subpopulations of Gold-edged Gem are at least 1100 km from the nearest known subpopulations in Colorado, therefore there is no possibility of individuals from Colorado re-colonizing Canada as it is far beyond their dispersal abilities. There is the possibility that Gold-edged Gems exist in unsurveyed sand hills in the intervening states. The Minot Dune Field in North Dakota (Muhs and Wolfe 1999) is 125 km from Spirit Sands, with the Lauder SH acting as a potential “stepping stone”. The Pembina County Sand Hills and North Dakota Dunes are about respectively 120 and 200 km (respectively) from Spirit Sands as well. Although there are no records of Gold-edged Gems from North Dakota, there has been little or no documented survey effort for them.

North Dakota has the US dunes that are closest to Canadian Gold-edged Gem subpopulations. They are still unlikely to be sources of recolonization if the Spirit Sands subpopulation was extirpated, due to unsuitable intervening habitat. If Canadian subpopulations are extirpated it will likely be due to loss of habitat, which would render the possibility of rescue from US subpopulations remote (because there would be no suitable habitat for them to recolonize).


Threats and limiting factors

The progressive stabilization of active sand dunes and blowouts is the most significant threat to the Canadian Gold-edged Gem population (COSEWIC 2006; Environment Canada 2014). Using the International Union for Conservation of Nature (2013) threats assessment calculator, overall threat impact was considered Medium.

Natural system modifications (7)

Dune stabilization is the most important threat to Gold-edged Gem subpopulations and habitat, particularly at small (<1 ha) blowouts that now support most of the known occurrences. This is a pervasive and continuing threat at all known sites throughout its Canadian range, and is largely driven by long-term climate trends (see Habitat Trends).

Fire suppression is considered a serious threat to Gold-edged Gems because it contributes to loss of habitat due to dune stabilization. Wildfire is now relatively uncommon within the Canadian range of the Gold-edged Gem; under historical conditions, anthropogenic fire may have been more widespread (Boyd 2004), and fire frequency has been estimated at 5-10 years (Wright and Bailey 1982). The removal of Bison may have also contributed to dune stabilization (see Habitat Trends). Although wildfire may kill local occurrences of Prairie Sunflowers and Gold-edged Gems, prairie wildfires tend to move rapidly, and dune habitats likely have relatively low fuel loads. Mortality may also be mitigated by the mobility of adults and if pupae are buried in the sand to a sufficient depth.

No non-native species are known to be predators, parasites, or competitors of Gold-edged Gem; however, they can indirectly impact this species through natural system modification. Invasive species can accelerate the process of dune stabilization compared to native species and may also negatively impact Prairie Sunflowers due to competition, thereby reducing the availability of suitable habitat for Gold-edged Gem. At Pakowki Lake SH, Crested Wheatgrass (Agropyron cristatum) and Tall Baby’s-breath (Gypsophila paniculata) were observed growing in dense stands near Gold-edged Gem habitat (Jensen et al. 2009). At Spruce Woods Provincial Park, Manitoba, sweet clover (Melilotus sp.), Smooth Brome (Bromus inermis), and particularly Russian Leaf Spurge (Euphobia virgata) are considered major problems for the long-term integrity and sustainability of the native habitat at this site (Schykulski and Moore 1996). Nearby farmsteads, gas wells, roads, and associated infrastructure in the sand hills near many known sites likely increase the likelihood of non-native species invading Gold-edged Gem habitat.

Limiting Factors

The distribution and abundance of Gold-edged Gems is inherently limited by the scarcity of open active sand dunes or blowouts with Prairie Sunflower subpopulations. Not all apparently suitable habitat is occupied in Canada, with Gold-edged Gems likely having microhabitat preferences based on sand dune topography, moisture, sand particle size, and plant community (COSEWIC 2006; Environment Canada 2014). Given Gold-edged Gem’s habitat and apparent host plant specificity and the scarcity of current active dunes in Canada, availability of suitable habitat is the primary biological factor limiting this species’ recovery (Environment Canada 2014).

Number of locations

According to the COSEWIC definition, a location is a geographically distinct area in which a single threatening event can rapidly affect all individuals of the species. Dune stabilization is the greatest single threat to Canadian Gold-edged Gem subpopulations. However, dune stabilization is ultimately driven by longer-term trends in regional climate and fire suppression, and non-climatic factors such as cattle grazing, fire, and other disturbance factors are likely important at the local scale for increasing dune activity (Hugenholtz et al. 2010). Local variation in land management may therefore be important in mitigating dune stabilization and reducing the threat to Gold-edged Gem populations. In addition, many Gold-edged Gem sites are relatively isolated from each other and are unlikely to be affected by a single threatening event. Based on these factors, each of the 14 sand hills in Canada may be considered to represent a separate location. The Great SH may actually represent more than one location given its large size, varying land tenure, and multiple known occurrences of Gold-edged Gem.


Protection, status and ranks

Legal protection and status

The Gold-edged Gem has been listed as Endangered under Schedule 1 of the federal Species at Risk Act since 2007 and was listed by the province of Manitoba under its Endangered Species and Ecosystems Act as Endangered in 2012 (Manitoba Wildlife Branch 2015). Critical habitat for Gold-edged Gem sites was defined in the 2014 federal recovery strategy, for Dune Point, Pakowki Lake, Middle, Burstall, and Tunstall SH. (Environment Canada 2014), and critical habitat on Suffield NWA in the Middle SH was recently gazetted (Government of Canada 2016).

Gold-edged Gem is not listed under the US Endangered Species Act or the Convention on International Trade in Endangered Species of Wild Fauna and Flora.

Non-legal status and ranks

The Gold-edged Gem is globally ranked as imperilled (G1G3, rounded to G2) and nationally ranked as critically imperilled (N1) in Canada (NatureServe 2015). It is also ranked as critically imperilled (S1) in Alberta, Saskatchewan, and Manitoba. In the United States, the Gold-edged Gem is unranked nationally (NNR) and in Colorado (SNR), the only state where the species is known to occur (NatureServe 2015).

Habitat protection and ownership

Eleven Gold-edged Gem occurrences (Antelope, Burstall, Great, Pakowki Lake, Seward, and Westerham sand hills) are on Crown land with grazing leases, and six others (Dundurn, Tunstall and Elbow sand hills) are on lands that were formerly Prairie Farm Rehabilitation Administration (PFRA) community pastures (now in the process of being divested by the federal government). Three other occurrences in the Elbow SH are in Douglas PP. The Manitoba subpopulation of Gold-edged Gems is largely within Spruce Woods PP and immediately adjacent portion of CFB Shilo. Nine occurrences in the Middle and Bowmanton sand hills are on Suffield NWA at CFB Suffield. Two known occurrences (Dune Point and Burstall sand hills) are located on private lands and the remaining one (Cramersburg SH) is on the Carry the Kettle Nakoda First Nations (I.R. 76-33).


Acknowledgements and authorities contacted

The authors wish to thank Paul Grant, Jenny Heron, Angèle Cyr, and Shirley Sheppard at COSEWIC for contract supervision, administration, and advice, as well as the Arthropods Species Specialist Subcommittee for document review and threats assessment. Conservation Data Centres from Alberta (Dragomir Vujnovic), Saskatchewan (Carolyn Gaudet), and Manitoba (Chris Friesen, Colin Murray) shared element occurrence data and background information for Gold-edged Gem surveys. Victoria Snable, Medea Curteanu, and Lynn Burns (Canadian Wildlife Service, Environment and Climate Change Canada) generously provided field observations, insight, and data. Chuck Harp and Paul Opler shared their knowledge of American subpopulations.

Saskatchewan and Alberta ranchers are thanked for granting access to their properties and stewardship thereof.

The following authorities were contacted during the preparation of the COSEWIC status report and are thanked for their insight:

Anweiler, Gary.C. Associate, Strickland Museum, University of Alberta, Edmonton, AB.

Curteanu, Medea. Wildlife Biologist, Canadian Wildlife Service, Edmonton, AB.

Heron, Jennifer. Invertebrate Specialist. BC Ministry of Environment, Vancouver, BC.

Harp, Charles (Chuck) E. Schinia specialist. Littleton, CO.

Kondla, Norbert G. Lepidopterist, Calgary, AB.

Lafontaine, Don, Entomologist (noctuid specialist), Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, ON.

Opler, Paul. Professor of Entomology, Colorado State University, Fort Collins, CO.

Snable, Victoria. Wildlife Biologist, Canadian Wildlife Service, Edmonton, AB.

Sovell, John. Invertebrate Zoologist and Ecologist, Colorado Natural Heritage Program, Colorado State University, Fort Collins, CO


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Biographical summary of report writers

Robert Foster is co-founder and principal of Northern Bioscience, an ecological consulting firm offering professional consulting services supporting ecosystem management, planning, and research. Dr. Foster has a B.Sc. in Biology from Lakehead University and a D. Phil in Zoology from the University of Oxford. Rob has worked as an ecologist in Canada for over 25 years and has conducted numerous insect surveys for protected areas planning and environmental assessments in Ontario, as well as Manitoba, Minnesota, Quebec, and British Columbia. Rob has authored or coauthored over twenty COSEWIC status reports on vascular plants, a land snail, and arthropods, including seven butterflies and moths, as well as Gibson’s Big Sand Tiger Beetle.

Allan Harris is a biologist with over 25 years’ experience in northern Ontario. He has a B.Sc. in Wildlife Biology from the University of Guelph and a M.Sc. in Biology from Lakehead University. After spending seven years as a biologist with Ontario Ministry of Natural Resources, he co-founded Northern Bioscience, an ecological consulting company based in Thunder Bay, Ontario. Al has authored or coauthored dozens of scientific papers, technical reports, and popular articles, including COSEWIC status reports for the Monarch, Nuttall’s Sheep Moth, Lake Huron Grasshopper, Riverine Clubtail, Laura’s Clubtail, Rapids Clubtail, Gibson’s Big Sand Tiger Beetle, Northern Barrens Tiger Beetle, Powesheik Skipperling, Mormon Metalmark, Weidemeyer’s Admiral, Bogbean Buckmoth, Hop-tree Borer, Georgia Basin Bog Spider, Broad-banded Forestsnail, Nahanni Aster, Crooked-stem Aster, Bluehearts, Drooping Trillium and Small-flowered Lipocarpha. Al also authored the Ontario provincial status report for woodland caribou, and has authored or coauthored national and provincial recovery strategies for vascular plants and birds.


Collections examined

The following collections were searched for Canadian specimens of the Gold-edged Gem.

Chicago Field Museum, Chicago, IL. (online search)

Royal Alberta Museum, Edmonton, AB. (Matthias Buck)

Royal British Columbia Museum, Victoria, BC. (Claudia Copley)

Spencer Entomological Collection, Beaty Biodiversity Museum, University of British Columbia, Vancouver BC (Karen Needham)

Yale Peabody Museum of Natural History, New Haven, CT (on-line search)

See COSEWIC (2006) for other collections were searched during the preparation of the original status report.


Appendix 1. IUCN Threats Calculator results for Gold-edged Gem (Schinia avemensis) in Canada.

The classification below is based on the IUCN-CMP (World Conservation Union–Conservation Measures Partnership) unified threats classification system. 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 assessment worksheet

Species or ecosystem scientific name:
Gold-edged Gem (Schinia avemensis)
Element ID:
-
Elcode:
-
Date:
07/12/2015
Assessor(s):
Rob Foster (co-writer), Paul Grant (SSC Co-chair), Jenny Heron (SSC Co-chair), Angèle Cyr (COSEWIC Secretariat), Medea Curteanu (CWS), Ruben Boles (CWS), Chris Schmidt (SSC - Moth expert).
References:
-
Overall threat impact calculation help:
Threat impactThreat impact (descriptions)Level 1 threat impact counts:
high range
Level 1 threat impact counts:
low range
AVery high00
BHigh00
CMedium11
DLow00
-Calculated overall threat impact:MediumMedium
Assigned overall threat impact:
C = Medium
Impact adjustment reasons:
-
Overall threat comments:
some of the quantified threats are for unsurveyed sites
Threats assessment worksheet table.
#ThreatImpact
(calculated)
Scope
(next
10 yrs)
Severity
(10 yrs
or
3 gen.)
TimingComments
1Residential and commercial developmentNegligible---Residential and commercial development are not considered threats to the Canadian population of Gold-edged Gem because active dune areas are generally unsuitable for these types of development. There are a few ranch houses in the sand hills occupied by Gold-edged Gem but the vast majority are at least 1 km from the nearest known Gold-edged Gem site.
1.1Housing and urban areas----Not applicable.
1.2Commercial and industrial areasNegligible---Not applicable
1.3Tourism and recreation areas----Not applicable. Some sand dunes are used for ATV courses but none existing or planned at known Gold-edged Gem sites
2Agriculture and aquacultureNot a ThreatPervasive
(71-100%)
Neutral or Potential BenefitHigh (Continuing)-
2.1Annual and perennial non-timber crops----Not applicable
2.2Wood and pulp plantations    Not applicable
2.3Livestock farming and ranchingNot a ThreatPervasive (71-100%)Neutral or Potential BenefitHigh (Continuing)Ranching of cattle is widespread at occupied (and unsurveyed sites) and potentially represents a threat to local subpopulations if cattle eat the host plant. However, grazing and trampling by cattle help slow the rate of dune stabilization (which is a greater known threat), so overall likely have a neutral or positive effect
2.4Marine and freshwater aquaculture    Not applicable
3Energy production and miningNegligible (<1%)Negligible (<1%)Extreme
(71-100%)
High (Continuing)-
3.1Oil and gas drillingNegligible (<1%)Negligible (<1%)Extreme
(71-100%)
High (Continuing)Over the past several decades there has been a dramatic increase in natural gas ex-traction activities and associated infrastructure (e.g., gas wells, trails, pipelines, compressors) in the sand hills in southwestern Saskatchewan and adjacent Alberta (Hugenoltz et al. 2010). For example, the number of gas wells in the Great SH doubled be-tween 1991 and 2005 (Government of Saskatchewan 2007), and there is oil or gas activities in the Antelope and Seward sand hills as well. The footprint of these activities is relatively small however and typically located on level and stable ground. Although often in close proximity, none appear to have been developed on occupied Gold-edged Gem habitat in active dunes and blowouts. Oil and gas activity, and their associated roads (see Transportation and Service Corridors) can facilitate the introduction of invasive, non-native plants (see Invasive and other Problematic Species and Genes).
3.2Mining and quarrying----Not applicable
3.3Renewable energy----Not applicable
4Transportation and service corridorsNegligible (<1%)Small
(1-10%)
Negligible (<1%)High (Continuing)-
4.1Roads and railroadsNegligibleSmall
(1-10%)
Negligible (<1%)High (Continuing)There is an increasing extent of access corridors associated with natural gas extraction in southwestern Saskatchewan, with more than 240 km of new access roads and trails constructed between 1991 and 2005 to access the oil and gas wells in the Great SH (Government of Saskatchewan 2007; Hugenoltz et al. 2011). Based on field observations and a review of satellite imagery, none appear to have been built through occupied Gold-edged Gem habitat. Given the infrequent use and relatively low vehicle speeds on these access roads, the risk of mortality to adult Gold-edged Gems is probably minimal. Although Prairie Sunflowers do grow in disturbed sandy areas along some of these roadsides, surveys have not detected any use by Gold-edged Gems (Curteanu et al. 2011; Curteanu pers. comm. 2015). The vast majority of known Gold-edged Gem sites are at least several hundred metres from the nearest road access.
4.2Utility and service lines----Not applicable
4.3Shipping lanes----Not applicable
4.4Flight paths----Not applicable
5Biological resource use-----
5.1Hunting and collecting terrestrial animals----Not applicable
5.2Gathering terrestrial plants----Not applicable. The occasional collecting of small numbers of Gold-edged Gems for scientific voucher specimens does not represent a threat to Gold-edged Gem subpopulations. Other resource use (e.g., gathering, logging, fish) do not occur in Gold-edged Gem habitat.
5.3Logging and wood harvesting----Not applicable
5.4Fishing and harvesting aquatic resources----Not applicable
6Human intrusions and disturbanceNot a ThreatNegligible (<1%)Neutral or Potential BenefitHigh (Continuing)-
6.1Recreational activitiesNot a ThreatRestricted (11-30%)Neutral or Potential BenefitHigh (Continuing)Sand dunes are popular with all-terrain vehicle (ATV) users and ATV tracks have been observed at a small number of dunes or blowouts that have Gold-edged Gem use (Curteanu pers. comm. 2015; Foster pers. obs.). ATV tracks tend to be primarily on bare sand areas, and often avoid steep dune rims where sunflowers tend to be most common, presumably due to the risk of ATV flipping. Nonetheless, there is a small risk of Prairie Sunflowers and Gold-edged Gems (particularly pupae) being crushed by ATVs. This risk is partially mitigated by the beneficial effect that ATV use likely has on slowing down the rate of dune stabilization. Gold-edged Gems and their habitat could be similarly impacted by high visitor use at occupied sites at Elbow SH in Douglas Provincial Park (PP) and at Spirit Sands (Brandon SH) in Spruce Woods PP. Most of the thousands of visitors annually at Spirit Sands likely stay on the marked self-guiding trail, but there remains a small risk of trampling. Visitor use is lower at Douglas PP, and fewer visitors likely stray into occupied Gold-edged Gem habitat. Trampling by visitors may also have a beneficial effect in helping slow the rate of dune stabilization at a local scale.
6.2War, civil unrest and military exercisesNot a ThreatSmall
(1-10%)
Neutral or Potential BenefitHigh (Continuing)  Military exercises could potentially affect Gold-edged Gems or their habitat at Canadian Forces Base (CFB) Shilo in the Brandon SH and within the CFB Suffield National Wildlife Area (NWA) in the Middle SH. Gold-edged Gem habitat is potentially present in adjacent CFB Suffield as well. Gold-edged Gems have also been found on community pasture immediately south of CFB Dundurn, and suitable habitat potentially appears on the base as well based on satellite imagery and a mapping by Wolfe (2010). Disturbance from military training and any associated fires may have a positive impact on Gold-edged Gem habitat by reducing dune stabilization, although there is a small risk of trampling by tanks, vehicles, or personnel.
6.3Work and other activitiesNot a ThreatNegligible (<1%)Neutral or Potential BenefitHigh (Continuing)There is a negligible risk from ranchers, gas workers, or other activities in the active dunes where Gold-edged Gem are found, mitigated by the potential benefits of disturbance on slowing dune stabilization.
7Natural system modificationsMedium (C)Pervasive
(71-100%)
Moderate
(11-30%)
High (Continuing)-
7.1Fire and fire suppressionNot a ThreatPervasive
(71-100%)
Neutral or Potential BenefitHigh (Continuing)Fire suppression, which promotes dune stabilization, is a threat to long-term persistence of the species in Canada (scored under 7.3). Fire is not considered a threat to the species as it evolved in landscapes where fire was prevalent. Local subpopulations of larvae would experience mortality from fire, but mobile adults and subterranean pupae may survive.
7.2Dams and water management/use----Not applicable
7.3Other ecosystem modificationsMedium (C)Pervasive
(71-100%)
Moderate
(11-30%)
High (Continuing)Dune stabilization and loss of habitat is the largest threat to this species. Processes such as fire suppression and introduction of invasive species (e.g., Russian Leaf Spurge, Baby's Breath, Crested Wheatgrass, sweet clovers) contribute significantly to dune stabilization. Dune stabilization is estimated at 10-20% per decade, and Gold-edged Gem occurs at smaller dunes that are more prone to stabilization. Cattle grazing and other disturbance is beneficial in slowing or reversing stabilization of dunes by vegetation. Droughts may be similarly beneficial in slowing dune stabilization (See Threats section).
8Invasive and other problematic species and genesUnknownUnknownUnknownUnknown-
8.1Invasive non-native/alien speciesUnknownUnknownUnknownUnknownNot applicable. No non-native species are known to be predators, parasites, or competitors of Gold-edged Gem. Indirect habitat-related effects of invasive non-native plants are discussed in 7.3 (See Threats section).
8.2Problematic native speciesUnknownUnknownUnknownUnknownElk or mule deer may browse Prairie Sunflower head but what impacts, if any, on Gold-edged Gems is unknown.
8.3Introduced genetic material----Not applicable
9PollutionNegligibleNegligible (<1%)Negligible (<1%)High (Continuing)-
9.1Household sewage and urban waste water----Not applicable
9.2Industrial and military effluentsNegligibleNegligible (<1%)Negligible (<1%)High (Continuing)Not applicable
9.3Agricultural and forestry effluentsNegligibleNegligible (<1%)Negligible (<1%)High (Continuing)It is unlikely that pesticides or herbicides are sprayed by ranchers on native prairie near Gold-edged Gem habitat. Gold-edged Gems, as well as Prairie Sunflowers and Rush Skeletonplant (or their pollinators), could potentially be impacted by the drift of agrochemicals used to control pest insects or weeds on adjacent agricultural fields or hayfields (e.g., Davis et al. 1991). However most known Gold-edged Gem occurrences are more than 1 km from adjacent agricultural fields so it appears that there is a negligible risk. The blowout at the Westerham SH and three blowouts at Patakowki Lake SH are within several hundred metres of agricultural fields, but it is unknown if there are any impacts from pesticide drift. Chemical control methods were used from 1983 to 2009 in Spruce Woods Provincial Park to control Russian Leaf Spurge (MCWS 2012). Impacts, if any, on Prairie Sunflower and Gold-edged Gem are unknown.
10Geological events---- 
11Climate change and severe weatherNegligibleNegligible (<1%)UnknownModerate (Possibly in the long term,
>10 years)
 The potential impact of climate change on Canadian Gold-edged Gems and their habitats is unknown. Decreased precipitation and increased mean annual temperatures and aridity associated with climate change could slow stabilization of dune habitats, particularly if there are prolonged and/or severe droughts (Hugenholtz et al. 2010). The impacts are difficult to predict however. Dune stabilization increased in the Canadian Prairies despite what appears to be progressive warming 1-2 °C of air and ground temperatures in the southern prairies since the early 1900s (Gullet and Skinner 1992; Majorowicz and Skinner 2001). It has been suggested that although higher air temperature leads to increased evaporation and aridity, it also increases the length of the growing season, thereby providing extended opportunity for plant growth and stabilization of dunes (Hugenholtz and Wolfe, 2005a; Wolfe and Hugenholtz 2009; Hugenholtz et al. 2010). Thus the long-term impact of climate change on future Gold-edged habitat may depend on the unknown interplay of temperatures, aridity, and vegetation dynamics. In the short-term, small, isolated subpopulations of Gold-edged Gem or Prairie Sunflower are likely vulnerable to stochastic events and could be threatened by hailstorms or severe early or late frosts, particularly if the frequency and intensity of severe weather events increases due to climate change.
11.1Habitat shifting and alterationNot a ThreatPervasive
(71-100%)
Neutral or Potential BenefitLow (Possibly in the long term,
>10 years)
Climate change in the long term (>10 years) will likely be beneficial for this species if warmer and more arid conditions slow or reverse dune stabilization and create more available habitat.
11.2DroughtsUnknownUnknownUnknownUnknownNot applicable. Direct impacts of droughts on Gold-edged Gem or Prairie Sunflowers are unknown, but the potentially beneficial role of droughts in slowing dune stabilization is included in 7.3
11.3Temperature extremesUnknownUnknownUnknownModerate (Possibly in the long term,
>10 years)
Early or late season frost, might have an impact on this moth, but scope and severity are currently unknown.
11.4Storms and floodingNegligibleNegligible (<1%)UnknownModerate (Possibly in the long term,
>10 years)
Hail storms and other events during the larval or adult activity period could have negative impacts on Gold-edged Gems or Prairie Sunflowers.

Glossary

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.
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%).
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 three-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%).
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.

Footnotes

Footnote 1

A sand dune is a “mound, hill or ridge of windblown sand, either bare or variously covered by vegetation, capable of movement from place to place through the development of a slip face, but always retaining its own characteristic shape for an extended period of time” (David 1977).
A blowout “refers to a small, typically less than 1 hectare in size, area of windblown sand, which is commonly bowl shaped and somewhat elongated in the direction of transporting winds. Thus, road tracks, all-terrain vehicle trails, cattle trails, oil/gas well pads, dugouts, cattle-disturbed areas around water wells sites and ranches, and sand pits” are not considered to be natural wind blown blowouts (Wolfe 2010)
The term sand hills refers to a well-defined geographic region where several sand dune occurrences exist (David 1977).

Return to footnote 1 referrer