COSEWIC Assessment and Status Report on the Edwards’ Beach Moth Anarta edwardsii in Canada - 2009
Committee on the Status
of Endangered Wildlife
Comité sur la situation
des espèces en péril
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. 2009. COSEWIC assessment and status report on the Edwards’ Beach Moth Anarta edwardsii in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 26 pp. (Species at Risk Status Reports)
For additional copies contact:
c/o Canadian Wildlife Service
Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur la noctuelle d’Edwards Anarta edwardsii au Canada.
Edwards’ Beach Moth -- Photo by Gary G. Anweiler.
© Her Majesty the Queen in Right of Canada, 2009.
Catalogue No.: CW69-14/573-2009E-PDF
COSEWIC Assessment Summary
COSEWIC Executive Summary
Edwards’ Beach Moth Anarta edwardsii
Edwards’ Beach Moth is a robust medium-sized (3.2 - 3.8 cm wingspan) species. The forewings are plain grey-brown with a line of black dots along the outer edge; and the hindwings are white with a broad dull black band on the outer half. Canadian populations belong to the nominate subspecies, which occurs throughout most of the species’ range. Inland populations in southern California and Arizona have been described as a separate subspecies.
Edwards’ Beach Moth occurs along coastal areas of southern Vancouver Island and the adjacent Gulf Islands of British Columbia south along the coast to southern California. It has a disjunct distribution and is apparently absent from most of coastal Washington and Oregon. It is presently known from only 2 locations in Canada. It was previously reported from two additional historic locations: Thetis Island (single specimens in 1966 and 1971) and Mill Bay on the Saanich Peninsula (one specimen in 1935).
This species has been captured in sparsely-vegetated sandy beach and beach dunes, including sandy beaches adjacent to saltmarshes. Substrates are generally medium-grained sand with vegetation cover ranging from 5–35%. Its larval host plant (or plants) in Canada is not known with confidence. Throughout its range, coastal populations tend to be concentrated in island complexes and inlets rather than on exposed, high-energy outer beaches.
Adults in Canadian populations fly from mid-May through July, in a single brood. There are no observations of mating, egg-laying, larval development, or pupation in Canada. Its dispersal abilitiesare unknown.
Population Sizes and Trends
There is no quantitative information on population sizes and trends for Edwards’ Beach Moth. Recent sampling indicates it can be locally abundant in suitable habitat. Various threats are resulting in habitat loss and have likely resulted in population declines; the species was not found at one historic locality in the most recent survey. It is known from two localities and three populations. Historically, it was known from an additional two localities and an additional three populations.
Limiting Factors and Threats
The limiting factors and threats to Edwards’ Beach Moth in Canada are: (1) habitat specialization confines its distribution to regionally rare and spatially isolated sandy coastal habitats; (2) loss of habitat is occurring as a result of sea level rise and increased frequency and intensity of storms that impact the sandy habitat; (3) exotic Scotch Broom and Fallow Deer have invaded its remaining sites in the Gulf Islands and both are causing a reduction in abundance of native vegetation.
Special Significance of the Species
Anarta edwardsii is part of a growing list of species restricted to sparsely vegetated sandy coastal ecosystems. These systems are exceptionally vulnerable to loss or degradation. The moth occurs in Canada in only two widely separated locations.
There is no information that suggests A. edwardsii has, or had, a significant social or economic role for First Nations.
Existing Protection or Other Status Designations
Anarta edwardsii is not specifically protected in any jurisdiction in Canada or the United States. Moths in two areas are protected under the general protection afforded wildlife in National Parks; a third site is partially protected by a Regional Park and another by a Conservation Covenant.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal–Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.
COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non–government science members and the co–chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.
- 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)*
- 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)**
- A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
- Data Deficient (DD)***
- 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.
COSEWIC Status Report on the
Edwards’ Beach Moth Anarta edwardsii in Canada 2009
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Technical Summary
- Information Sources
- Biographical Summary of Report Writers
- Authorities Consulted
- Collections Examined
List of Figures
- Figure 1: Adult Male Anarta Edwardsii
- Figure 2: Distribution of Anarta Edwardsii in North America
- Figure 3: Distribution of Anarta Edwardsii in Canada and Adjacent USA
- Figure 4: Habitat Characteristics at Sampling Areas where A. Edwardsii was Captured between 2001–2007
- Figure 5: Orthophotos of Island View Beach and Cordova Spit, Vancouver Island, 2005 and 2007 Showing Loss of Beach Due to Winter Storm Activity
List of Tables
- Table 1: Changes in Total Area and Land Cover in C. Fuscum Localities
- Table 2: Anarta Edwardsii Captures in Canada (2001–2007)
Taxonomic Background and Similarities
Until recently A. edwardsii was placed in the genus Trichoclea, which was synonomized with the genus Anarta (Fibiger & Hacker, 2005). The North American species of Trichoclea, including A. edwardsii, were transferred to Anarta by Mustelin (2006). Twenty-three additional species of Anarta occur in North America. Anarta edwardsii is distinct and is recognized as a valid species. Canadian populations belong to the nominate subspecies, which occupies most of the range of A. edwardsii. Inland populations in southern California and Arizona have been described as a separate subspecies, A. edwardsii deserticola (Hill).
Anarta edwardsii is a stocky medium-sized moth with a wingspan of 32–38 mm, (Figure 1). The head, thorax, abdomen, and antennae are uniform brown-grey. The forewing is relatively unmarked except for a prominent terminal line formed by a series of small black spots or wedges. The subterminal line is faint and rudimentary, comprised of a few black scales where the “line” crosses the veins. In most specimens the reniform spot is indicated by a few dark scales. The hindwings are bright white, crossed by a wide dark grey or dull black terminal band. Fringes are brown-grey on the forewings and white on the hindwings. Females tend to have darker forewings than do males.
The eggs of A. edwardsii have not been described.
The following larval and pupal descriptions are excerpted from Comstock and Henne (1941). Mature larvae are marked with faint whitish green “etching” over a pale green ground colour. The skin is faintly translucent, with the circulatory tube of the mid-dorsal area showing through as a darker green line. Subdorsal and dorsolateral whitish stripes bordered with dark green run longitudinally, beginning on the first thoracic segment and terminating close to the caudal area. The uppermost stripe is the most conspicuous. True legs and prolegs are somewhat paler than the body background colour. The spiracles are dark brown and the mandibles nearly black.
Pupae are approximately 19 mmlong, 6 mmwide and tapered at the ends. Immediately following transformation from the larvae they are light tan with a dark mid–dorsal strip on the abdominal segments. The spiracles are dark brownish black. The wing cases extend approximately two-thirds the distance to the caudal extremity. The eye cases are large and slightly protruding. The cremaster is composed of a small, slightly raised, laterally ridged plate located on the ventral surface of the caudal extremity, with two spines approximately 1 mm in length and sometimes bifurcate at the tips. Just prior to adult emergence the pupa takes on a dark reddish brown colour (Comstock and Henne 1941).
Limited genetic information is available for Anartaedwardsii. Partial barcode data (approximately 350 base pairs of the COIgene) for a single Canadian specimen of A. edwardsii is availableon the All Leps Barcode of Life project (Biodiversity Institute of Ontario, 2007).
Anarta edwardsii has occurred on beaches along the coast of both the east and west side of southern Vancouver Island and the adjacent Gulf Islands, south along the coast to San Diego, California. The known distribution of subspecies edwardsii is disjunct, with an apparent gap between the north coast of Washington and the southern coast of Oregon (Figure 2).
The desert subspecies deserticola occurs in inland desert in the Palm Springs area of southern California east to Arizona (California Moth Specimen Database, 2007; Walsh, no date) (Figure 2). The global extent of occurrence is approximately 350 000 km²based upon the convex polygon.
Anarta edwardsii has been collected on beaches along both the eastern and western coasts of southern Vancouver Island, as well as on several of the adjacent Gulf islands (Figure 3). It has been recorded in southern BC in only seven places over the past 15 years, and these represent only two localities as per COSEWIC definitions because all sample sites but one are clustered in a single small area. Recent searches at two of the previous collecting sites failed to find the moth. In addition to these, there are two historic specimen records from Thetis Island (1966 and 1971) and one from Mill Bay in Saanich Inlet (1935). The estimated extent of occurrence in Canada is 2050 km².
Using the 2X2 grid method, the estimated maximum current area of occupancy is 20 km² in Canada (28 km² if the two historic localities are included). Suitable habitat within this area (sparsely vegetated sandy habitat) is considerably less, as only about 10% of the calculated area is comprised of such habitat. Habitat area was mapped with 2002 orthophotos in Arcview GIS
In Canada, A. edwardsii is associated with regionally rare and discontinuous sparsely vegetated sand beach or sand beach bordering saltmarsh habitats. This habitat specificity influences population structure. These habitats occur where coastal erosion and transport of glacially derived sand deposits have created large depositional coastal features and sustained them over the long term. Sand-dominated coastal areas are generally rare in BC and are typically clustered spatially because of shared physiographic conditions and coastal processes.
Sand-dominated coastal habitats in British Columbia have been rapidly and extensively modified throughout the known range of A. edwardsii over the past 100 years. Detrimental effects vary in intensity and include recreational disturbance, construction of roads and buildings, modification of disturbance regimes (e.g., shoreline armoring), vegetation stabilization and impacts from invasive plants and herbivores. At least one area known for the species had agricultural activity prior to its becoming a park. Dunes, spits and other sparsely vegetated communities were the most poorly represented of seven sensitive ecosystem types that were inventoried on southeastern Vancouver Island between 1993 and 1997; only 39.5 ha. of dune and 111.3 ha. of spit were identified by air photo analysis and field assessment (Ward et al., 1998).
Sandy coastal and saltmarsh habitats were common during the early post-glacial period (Mosher and Thomson 2000) and the current isolation of Canadian A. edwardsii populations may be a product of long-term habitat change; existing populations may be remnants of a larger and better connected series of populations.
Estimating the number of populations and understanding population structure based on the potential dispersal between known localities is difficult because of the lack of information on dispersal ability of A. edwardsii.
The inland records from California and Arizona are spp. deserticola. The records off the coast of California are from the Channel Islands. The polygons show the EO for each subspecies.
Black dots denote recent (post-1990) specimen records; open circles denote older records (pre-1975), and dots with shaded centres are recent localities in adjacent WA. Grey triangles show coastal localities that were sampled by N.A. Page from 2001–2007 without capturing A. edwardsii.
Individuals of A. edwardsii from James Island (three trap sites) and Sidney Island (one trap site), which are less than 2 km apart across open water, are likely exchanged infrequently. However, dispersal among the three trap sites on James Island is more likely. Historically, limited dispersal between mainland Vancouver Island and the Gulf Islands likely occurred. It is less likely that there was any significant movement of individuals between Thetis Island or Mill Bay and any of the remaining populations, and movement of moths between the two remaining locations (West Vancouver Island and two Gulf Islands) is likely impossible (Figure 3).
Canadian A. edwardsii are therefore considered to comprise three extant populations; one on each of two Gulf Islands and one on the west coast of Vancouver Island. A population on the SE coast of Vancouver Island seems no longer extant. The historic sites from Thetis Island and Mill Bay may no longer be extant.
There is little information about the specific habitat requirements of A. edwardsii. In Canada, it has been captured in both sparsely vegetated sandy beach and dune habitats, as well as on sandy beaches adjacent to saltmarshes. Throughout its range, coastal populations tend to be concentrated in island complexes and inlets rather than on exposed high-energy outer beaches. It is unknown how important, if at all, the saltmarsh vegetation component is for A. edwardsii populations. Substrates are generally medium-grained sand, and vegetation cover ranges from 5–35%. Common plants in sandy beach habitats are Leymus mollis (Trin.) Pilger, Ambrosia chamissonis (Less.) Greene, Carex macrocephala Willd. ex Spreng, Lathyrus japonicus Willd., and Cakile edentula (Bigelow) Hook. Common saltmarsh plants include Distichlis spicata (L.) Greene, Salicornia virginica L. and Atriplex patula L.
The identification of habitat requirements for A. edwardsii is complicated by the limited knowledge about its larval host plant or plants in Canada. In the Channel Islands of southern California larvae were collected from and reared on a saltbush, Atriplex leucophylla (Moq.) D. Dieter (Comstock and Henne 1941). Atriplex canescens is listed as the larval host for the closely related Anarta antica in California, and the genus Atriplex is also listed as the larval host for European populations of Anarta trifoli and Indian Anarta arenaria (Natural History Museum 2007). Atriplex patula L. is common in saltmarshes and coastal beaches in the Georgia Basin, but was uncommon or absent at some places where A. edwardsii was captured.
Although Atriplex species are known to be a host plant for several species of Anarta, and a species of Atriplex is the only recorded host for A. edwardsii (in California) it should also be noted that Atriplex patula, which is not uncommon on some beaches and in saltmarsh habitats in southern BC, is apparently an introduced Old World species, and if so cannot have been the host for A. edwardsii prior to its introduction and establishment in this area. It is more likely that one or more species of native Chenopodeaceae is the host, or perhaps it uses one or more unrelated species, such as Abronia (Nyctaginaceae).
An analysis of vegetation at capture localities was undertaken by N. A. Page to better assess the association of specific plants with A. edwardsii. The following plants were most common and abundant within 15 m of traps in which A. edwardsii was captured: Abronia latifolia, Ambrosia chamissonis, Carex macrocephala, and Leymus mollis. However, these are common in many sandy beach areas in which A. edwardsii is apparently absent, and are not always present in areas where A. edwardsii occurs. Abronia latifolia is considered a rich resource for many noctuid moths, including Sand-verbena Moth (Copablepharon fuscum); however, it is not abundant in one area which supports a population of A. edwardsii, nor is it known to occur at Thetis Island or Mill Bay, localities where A. edwardsii was found historically.
Larval hosts of non-pest species of Noctuidae are not well studied, and whether or not most species of Anarta are restricted to one genus or even a single species of host plant or conversely use a wider range of hosts is not known. Larval hosts for only a very few of the more than two dozen North American members of the genus have been reported. At least one member of the genus Anarta (A. trifoli) which commonly uses Atripex as a host also feeds on a large range of other plants, including a variety of garden vegetables, and sometimes reaches pest status (Natural History Museum, 2007). Thus it is possible that A. edwardsii uses more than a single host plant.
The importance, if any, of saltmarsh vegetation to A. edwardsii populations is poorly understood. Anarta edwardsii is often abundant in sandy beaches adjacent to saltmarshes (see Figure 4), but has also been found (in lower abundance) >1 kmfrom saltmarsh vegetation. Additionally, A.edwardsii was not captured at several sampling localities (e.g.Boundary Bay, Tsawwassen causeway, Iona Beach, Lionsgate saltmarsh, portions of Goose Spit, and Witty’s Lagoon) which were specifically searched for noctuid moths of saltmarsh or saltmarsh/sand beach habitats.
The deserticola subspecies of A. edwardsiioccurs in dry grasslands and sandy washes in the interior of California and Arizona. Another moth within the same genus, A. antica, feeds on Atriplex canescens(Pursh) Nutt. in the deserts of California, Arizona and Nevada.
a) Sidney Island, BC; b) James Island, BC; c) dune with Abronia latifolia on James Island, BC; d) James Island, BC; e) dense patch of A. latifolia on Sidney Island, BC; and f) dune margin and saltmarsh (Dungeness Spit, WA). All photos by N.A. Page.
Without a better understanding of habitat requirements, it is difficult to infer habitat trends for A. edwardsii.However, based on the general information that it occurs in sparsely vegetated sandy coastal habitats, perhaps particularly those adjacent to saltmarshes, suitable habitat has declined.
Many sand-dominated coastal areas in the Georgia Basin have been modified throughout the known range of A.edwardsii over the past 100 years. These modifications have been due to construction of roads, buildings, and golf courses, alteration of disturbance regimes (e.g., shoreline armoring), recreational disturbance such as trail formation and use, and vegetation stabilization due to the effects of invasive plants. Invasive Scotch Broom and Fallow Deer are reducing the abundance of native vegetation in at least some of the sites where A. edwardsii has been collected. Natural habitat loss, such as spit erosion has also reduced the amount of sparsely vegetated sandy habitat in some areas, and increased storm frequency and intensity is increasing the rate of change in these areas. Dunes, spits, and other sparsely vegetated coastal plant communities were the most poorly represented of seven sensitive ecosystem types that were inventoried on southeastern Vancouver Island between 1993 and 1997; only 39.5 ha. of dune and 111.3 ha. of spit were identified by air photo analysis and field assessment (Ward et al., 1998).
Progressive loss of open sand habitats from vegetation stabilization is the primary cause of habitat decline for species requiring open coastal habits in Canada, e.g. Copablepharon fuscum ( COSEWIC, 2003). Sand-dominated coastal sites develop from sand accretion which is controlled by sediment transport processes (Thomson, 1981). Vegetation stabilization rates show similar temporal variability, and the recent stabilization trend in many dunes and spits in the Strait of Georgia may reflect a period of reduced sediment transport. It is more likely, however, that much of the recent vegetation stabilization is caused by anthropogenic impacts. In particular, the introduction of invasive exotic plant species such as Cytisus scoparius (Scotch broom) and a variety of exotic grasses (e.g., Bromus tectorum, Ammophila arenaria, Dactylis glomerata, Holcus lanatus, Bromus hordeaceus, Vulpia myuros, Anthoxanthum odoratum) has accelerated stabilization. Native mosses (Tortula ruralis, Racomitrium canescens, Ceratodon purpureus and Bryum capillare) function in concert with vascular plants rapidly colonizing the sand surface. Cytisus scoparius is the most important of the exotic species in sand-dominated coastal sites because of its rapid growth and ability to fix nitrogen in low fertility sand soils (Parker, 2002). Ammophila arenaria, a widespread invasive grass species of outer west coast beaches from B.C. to California (Wiedemann and Pickart, 1996), is also present in some dune sites in the southern Strait of Georgia. Increased log debris in some coastal sites may also contribute to stabilization.
Direct habitat loss from land development (e.g., roads, buildings, etc.) or recreational use has also resulted in habitat decline. Recreational uses may have contributed to localized damage to some plant communities, e.g.A. latifolia, although in other areas limited disturbance has maintained open sand areas.
Shoreline modifications, including erosion protection, may reduce sand supply and change transport and deposition patterns. This may contribute to stabilization of dunes.
Historic air photos were used to evaluate land cover change in the three Canadian areas also located on coastal southeastern Vancouver Island where C. fuscum, a related noctuid moth with similar sandy habitat requirements, occurs. Photos were scanned, adjusted to a common scale, and land cover types (urban, tree and shrub, grass and bryophyte, and open dune) were measured. For the two northern areas, photos from 1957 were compared to 1995 or 1997 photos. For the southern area, photos from 1932 were compared to 1995.
|Place 1 (Comox area, B.C.)|
|Place 2 (Comox area, B.C.)|
|Place 3 (near Sidney, B.C.)|
In general, all three regions show relatively little overall change in total area and similar but variable loss of open dune habitat (Table 1). Two places enlarged slightly (0.7 ha. and 0.1 ha.increases) because of sand accretion, while the other remained stable. Open dune areas declined in all places; two places lost 50% of their open dune area (loss of 2.2 and 0.4 ha.), while the other lost 21% (loss of 0.5 ha.). Grass and bryophyte areas also declined in all places; one place lost over 52%, while the others lost 6% and 13%. Forest and shrub cover increased substantially in all places: 134% in one place, 46% in another and 220% in the third (gain of 4.7, 0.6 and 1.1 ha.). Only one area had urban land use and increased from 2.6 ha. to 9.2 ha. (254% increase) since 1957.
Recent increased intensity and frequency of winter storms has resulted in an increased rate of sand transportation in areas that are not stabilized (Fig. 5).
One place where the species has been found on Sidney Island is protected as part of Southern Gulf Islands National Park Preserve. James Island is entirely privately owned, but much of the habitat suitable for A. edwardsii is becoming protected through a Conservation Covenant. The sites of two Canadian historic records of A. edwardsii (Thetis Island and Mill Bay) are most likely privately owned, but the exact positions where the specimens were collected are not known. Areas on southeastern Vancouver Island are primarily on First Nations land, with smaller areas in a Regional (0.9 ha.) and Municipal Park (1.8 ha.). One population is protected as part of Pacific Rim National Park. However, the protection afforded the moth by these “protected” areas is not effective against some of the threats faced by the species.
Current knowledge of the biology of A. edwardsii is based on limited field sampling supplemented with minor information for California populations (Comstock and Henne, 1941; Hill, 1924), and observations by Lars Crabo in Washington (pers. comm.).
The capture dates of adults in Canada indicate a single annual brood, with the flight period extending from mid-May through July. Populations in California appear to be double-brooded, with adults flying from mid-April through July, and again in October and November. Reproduction coincides with the flight season and adult moths likely die shortly after reproducing.
Mating, egg laying, pupation, and larval feeding behaviour in Canada have not been observed. Comstock and Henne (1941) provide morphological observations of larvae and pupae from southern California but do not provide ecological information other than their capture of larvae from Atriplex leucophylla plants along the shoreline.
The only reported larval host plant for A. edwardsiiis the saltbush Atriplex leucophylla; larvae were found on this plant, which wasgrowing along the shoreline of the Channel Islands in southern California (Comstock and Henne 1941). Related species of Anarta, including A. decepta (North America), A. arenaria (India), and A. trifoli(Holoarctic), also use Atriplexspecies as larval hosts. The first two have been recorded only from Atriplex while A. trifoli also uses a wide range of plants in other families including garden vegetables and particularly Clover (Trifolium) on which it sometimes reaches pest status. Atriplex patula is present in saltmarshes and beach edges in A. edwardsii habitat in coastal BC, and is a logical suspect as the host plant. However, it appears to be rare or absent from some places where the moth is present. Furthermore, A. patula is an introduced exotic plant, and while it may now be used as a host plant, it cannot have been the original host plant in this area, unless A. edwardsii arrived here from the south since A. patula was introduced, which seems unlikely. It is more probable that A. edwardsii feeds on one or more of the “fleshy” herbs in and adjacent to the sandy beach habitats it frequents, members of the family Chenopodiaceae being the most likely. The fleshy beach plant Abronia latifolia is known to be palatable to noctuid moths as it is the only known host of the endangered Copablepharon fuscum.which occurs at some of the same places as A. edwardsii (COSEWIC 2003).
Annual and longer-term survival rates are unknown. There is no information on predation, intra- or inter-specific competition, disease or other factors that may affect survival of A. edwardsii.
In Canada, Anarta edwardsii flies during the onset of warmer weather in early to mid-summer. It is assumed that larval growth occurs during late summer and early fall. Larval overwintering activities are unknown. It is unknown how seasonal temperature changes affect adult flight periods, mating, or larval survival.
Climate may be an important limiting factor for A. edwardsii’s distribution. It is unknown how seasonal temperature changes affect adult flight periods, mating, or larvae survival.
Dispersal abilities of A. edwardsii have not been assessed and are difficult to infer from other species. Given that sandy habitats are often patchily distributed across a landscape it is likely that dispersal at this scale is frequent. However, regional dispersal between more isolated habitats (e.g., landscape-level dispersal >10 km) or across the ocean among islands is considered unlikely or very infrequent.
Anarta edwardsii is not known to migrate or otherwise undertake large-scale movements on a regular basis.
Anarta edwardsii larvae were found feeding on A. leucophylla in California (Comstock and Henne, 1941). No other interspecific interactions are known.
There is no information on adaptability for A. edwardsii. It has not been bred in captivity, although Comstock and Henne (1941) apparently used captive-raised individuals for their morphological observations.
Two sampling strategies were used to search for A. edwardsii. First, moths were trapped in sand beaches and adjacent dune or coastal meadow habitats as part of a larger survey for Sand-verbena Moth, Copablepharon fuscum, and other beach moths in coastal BC(see Fig. 3). Sampling area selection was general in approach and attempted to sample different plant communities and substrate conditions within coastal habitats. A total of 35 sample localities in coastal BC, including the west coast of Vancouver Island and the Puget Sound area of WA, were sampled between May 2001 and June 2007, with 1 to 3 traps used per locality. Repeat sampling was conducted at several localities and a total of 60 trap nights (1 trap for 1 night = 1 trap night) of sampling was completed. Figure 3 shows where much of the sampling took place. All trapping was undertaken using battery-operated modified Robinson light–traps.
There was also targeted sampling of plant communities with A. patula in 12 areas in coastal BC because of the reported association between A. edwardsii and A. leucophylla in California. These included some sand beach habitats as well as saltmarsh ones with A. patula.
During these surveys a total of 266 A. edwardsii adults were captured at sample sites on James Island, Sidney Island, the West Coast of Vancouver Island and also in Washington State (Dungeness Spit). One area on Sidney Island was sampled repeatedly (2001, 2004, 2006, and 2007) to better refine habitat characteristics. Lars Crabo also found A. edwardsii at the base of Dungeness Spit, WArepeatedly in the early 1990s, and also recently captured large numbers (>50) adjacent to a saltmarsh on Henry Island, WA (immediately east of Roche Harbour on San Juan Island). There is also an unconfirmed record from Roche Harbour, WA (L. Crabo, pers. comm.). Additional records of A. edwardsii collected in coastal southern BC by J. Troubridge were obtained from specimens in the Troubridge collection now housed in the University of Alberta Strickland Museum collection (UASM).
Table 2 summarizes the sample localities and number of A. edwardsii caught by N.A. Page over the study period; it does not include records provided by L. Crabo for Washington.
The species has not been found where two historic records are known from the work of Troubridge (Cordova Spit and Island View Beach where it had been found in 1994-1995) despite searches for it there in more recent years by N.A. Page.
|Sample Locality||Date||No. Captured per Trap|
|Pacific Rim National Park||June 12, 2001||1*|
|Sidney Island||July 23, 2001||23|
|Sidney Island||June 11, 2002||11|
|Dungeness Spit, WA||June 12, 2002||3|
|Sidney Island||June 11, 2004||1|
|Sidney Island||June 23, 2006||4|
|Sidney Island||June 23, 2006||1|
|James Island||June 27, 2007||177|
|James Island||June 27, 2007||19|
|James Island||June 27, 2007||27|
By N.A. Page.
* Number collected this date not known; 1 specimen deposited in UASMcollection
A total of 266 A. edwardsii specimens were captured, ranging from 1 per trap to 177 per trap (mean of 30 per trap) during recent sampling by Page (Table 2). As an indicator of local abundance, A. edwardsii was often the most abundant moth captured where it occurred. The large number of individuals (177) trapped at one of the James Island localities demonstrates that while being regionally rare, A. edwardsii can be locally abundant.
Because of uncertainties in measuring capture success, suitable habitat, and other factors, a population estimate cannot be calculated for A. edwardsii using the available data.
There are no data regarding population fluctuations and trends for A. edwardsii. The inherent difficulty in assessing population sizes, variability, and trends in rare, nocturnal insects has greatly reduced the potential for detailed population information. Loss or degradation of sandy beach habitat and saltmarsh habitats adjacent to sandy beaches as well as the natural vegetation cover of these habitatas could be expected to have impacts corresponding in magnitude to the extent of habitat loss or degradation. There are no data to indicate measurable population fluctuations. Trends in habitat loss and degradation are expected to be negative overall.
The closest known population of A. edwardsii to those in Canada separates the James and Sidney island areas from Henry Island, WA. The distance is approximately 12 km (across open water). Dungeness Spit, WA moths are approximately 52 km further to the south, 32 km of which is over water. Rescue through dispersal of moths from Henry Island is possible in the long term, but it is unlikely from Dungeness Spit.
Anarta edwardsii is associated with both sparsely vegetated sandy habitats and sandy beaches adjacent to saltmarshes. While its specific habitat requirements, particularly its larval host plant(s), are unknown, its association with a rare coastal habitat is considered a limiting factor because it confines distribution to regionally rare and spatially isolated coastal habitats.
The primary threat to A. edwardsii is loss or degradation of sparsely vegetated sandy beach habitats from natural or anthropogenic disturbance.
The potential effects of climate change on A. edwardsii are complex, but likely mostly negative. Sea-level rise will threaten habitat directly. Sand spits and dunes are particularly prone to loss when sea level rise is accompanied by storms of increased frequency and intensity. Past sea level rise in Victoria has been estimated at 3.1 cm/50 year period using records from 1910-2003 (BC Ministry of Environment, 2008). However, accelerated coastal disturbance and sediment transport associated with increased storm frequency may result in increased development of open sand habitats, which could have a positive effect. Nonetheless, the movement of sand during winter storms will inevitably expose overwintering individuals to increased predation.
The increasing incidence of intensive storms is resulting in increased loss of sandy habitat in the SE portion of the species’ range in Canada. Figure 5 shows changes in sandy habitat in the Cordova Spit and Island View Beach area of Vancouver Island, where A. edwardsii seems to have become extirpated recently. Considerable change can be seen between 2005 and 2007 as a result of severe winter storms and these have continued.
Figure 5: Orthophotos of Island View Beach and Cordova Spit, Vancouver Island, 2005 (left) and 2007 (right) showing loss of beach due to winter storm activity. More losses occurred in the 2008/2009 winter.
Recreational disturbance and coastal development have reduced the amount and quality of habitat. James Island has recently seen development, but the conservation covenant between the landowner and NCC for the sandy regions on the west, north and northeast parts of the island prohibits development in the important habitat for the species and provides opportunities for active conservation.
Introduced Scotch Broom and Fallow Deer are causing ecological havoc on James and Sidney Islands. Scotch Broom outcompetes the native vegetation, while the Fallow Deer consumes the native vegetation but generally avoids eating the invasive plant.
The Sand-verbena Moth is an endangered species that is restricted to similar sand beach and dune habitats to those occupied by A. edwardsii in south coastal BC. Other rarely collected noctuid moths that are more or less restricted in Canada to coastal beaches in southern BC include: Apamea maxima (Dyar), Oligia tusa (Grote), Lasionycta wyatti (Barnes & Benjamin), Lasionycta arietis (Grote), Agrotis gravis Grote, and Euxoa wilsoni (Grote) (Troubridge and Crabo, 1996).
Anarta edwardsii is a species with a very restricted range in Canada. It is only found in sandy, sparsely vegetated, coastal ecosystems in BC that are declining because of habitat loss or change.
There is no information that suggests A. edwardsii has, or had, any social or economic role for First Nations.
Anarta edwardsii is not protected as such in any jurisdiction in Canada or the United States. Two populations are protected under the general protection afforded wildlife in National Parks, one is partially protected by a Regional Park and another is becoming protected through a conservation covenant. There is insufficient information in the USA about this species to reasonably categorize its status (Natureserve, 2007).
Range of Occurrence in Canada: southwestern British Columbia (southern Vancouver Island and adjacent Gulf Islands)
the population) 1 year or less
number of mature individuals over the last
[10 or 5 years, or 3 or 2 generations] Unknown but some decline likely due to loss of one population since 1994
number of mature individuals over the next
[10 or 5 years, or 3 or 2 generations] Unknown; probable decline due to loss of sandy habitats and impacts of invasive species
number of mature individuals over any
[10 or 5 years, or 3 or 2 generations]
period, over a time period including both
the past and the future Unknown; probable decline due to loss of sandy habitats and impacts of invasive species
Extent and Area Information
Number of mature individuals in each population
locations 2 (historically 4)
Rescue Effect (immigration from an outside source)
Recommended Status and Reasons for Designation
Reasons for designation:
In Canada, this species of noctuid moth has only been found in sparsely vegetated sandy beach and dune habitats on the coast of Vancouver Island and two small adjacent Gulf Islands. Together, these constitute only two locations. The habitats are at risk from succession, invasive species, recreational activities and changing patterns of sand deposition resulting from increasing frequency and intensity of winter storms. It is currently known from James and Sydney Islands and Pacific Rim National Park. The chance of genetic exchange is minimal between Pacific Rim and other areas and low between the Gulf Islands. One population has not been detected in recent times, and the species could not be found at 38 other locations where there appeared to be suitable habitat.
Applicability of Criteria
Criterion A (Decline in Total Number of Mature Individuals): Insufficiently known
Criterion B (Small Distribution Range and Decline or Fluctuation): Meets Endangered B1ab(i,ii,iii,iv)+2ab(i,ii,iii,iv) as EO is less than 5000 km², IAO is at most 24 km² in two widely separated areas, one population has been lost since 1994, and there is a continuing reduction in quality of habitat due to increased winter storm frequency and intensity, browsing by invasive deer and competition between larval food plants and invasive Scotch Broom.
Criterion C (Small and Declining Number of Mature Individuals): Insufficiently known
Criterion D (Very Small Population or Restricted Distribution): Meets Threatened D2 as there are less than 5 locations.
Criterion E (Quantitative Analysis): not performed
British Columbia Ministry of Environment, 2008 Environmental Trends in British Columbia: 2007
California Moth Specimen database. 2007. (Online) (7 September 2007).
Comstock, J. A. and C. Henne. 1941. The larvae and pupa of Trichoclea edwardsii Sm. Bulletin of the Southern California Academy of Science 40: 165-166.
COSEWIC. 2003. COSEWIC assessment and status report on the Sand-verbena Moth Copablepharon fuscum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 39 pp.
Fibiger, M. and Hacker, H. 2005. Systematic list of the Noctuidae of Europe (Notodontidae, Nolidae, Lymantriidae, Arctiidae, Erebidae. Micronoctuidae, Noctuidae). Esperiana, 11: 76-690.
Hanski, I. 1982. Dynamics of regional distribution: the core and satellite species hypothesis. Oikos 38: 210–221.
Hill, C. A. 1924. Pacific coast Lepidoptera No. 1 (Noctuidae). Some apparently new species of moths of the family Noctuidae and one saturnid aberration from the southwestern United States. Bulletin of the Southern California Academy of Sciences, 23, 182–186.
Jones, L.J.R.J. 1951. An Annotated Checklist of the Macrolepidoptera of British Columbia. Entomological Society of B.C., Occ. Papers No.1.
Lafontaine, J. D. and R. W. Poole. 1991. Noctuoidea, Noctuidae, Part Plusiinae
Moths of America North of Mexico including Greenland. Wedge
Entomol. Res. Found., Washington, D.C. Fasc. 25.1,182 p.
Mosher, D.C. and R.E. Thomson. 2000. Massive submarine sand dunes in the eastern Juan de Fuca Strait, British Columbia. Marine Sandwave Dynamics, International Workshop, March 23-24, 2000. University of Lille 1, France, Proceedings, Trentesaux, A., and Garlan, T. (Eds.), p.131-142.
Mustelin, T. 2006. Taxonomy of Southern California Erebidae and Noctuidae (L.) with descriptions of twenty-one new species. Zootaxa 1278:1-47.
Parker, I.M. 2002. Safe site and seed limitation in Cytisus scoparius: Invasibility, disturbance, and the role of cryptogams in a glacial outwash prairie. Biological Invasions 3(4): 323-332.
Smith, J. B. 1888. New genera and species of North American Noctuidae. Proceedings of the United States National Museum Vol. X, p. 460-479.
Thomson, R.E. 1981. Oceanography of the British Columbia Coast. Can. Spec. Publ. Fish. Aquat. Sci. 56. 291 pp.
Troubridge, J. T. and J. D. Lafontaine. 2007. The Moths of Canada. Noctuidae Part 3.5: Hadeninae: Hadenini. Canadian Biodiversity Information Facility (PDF Version, 4 557 KB). (Online) (3 September, 2007)
Troubridge, J. T. and L. G. Crabo. 1996 . A new species of Copablepharon (Lepidoptera: Noctuidae) from British Columbia and Washington. Journal of the Entomological Society of British Columbia 92: 87–90.
Walsh, B. The Moths of Southeastern Arizona: Noctuidae (Cutworm moths) website. Accessed June 2008.
Ward, P., G. Radcliffe, J. Kirkby, J. Illingworth and C. Cadrin. 1998. Sensitive
Ecosystems Inventory: East Vancouver Island and Gulf Islands 1993-1997. Volume 1: Methodology, Ecological Descriptions and Results. Technical Report Series No.320, Canadian Wildlife Service, Pacific and Yukon Region, British Columbia. 264 pp.
Wiedemann, A.M. and A. Pickart. 1996. The Ammophilaproblem on the Northwest Coast of North America. Landscape and Urban Planning 34: 287-299.
Nicholas A. Page is a biologist who works on the assessment and management of species and ecosystems. His project work includes watershed planning, plant community ecology, and studies of rare invertebrates. He completed a Master of Science degree in the Institute for Resources, Environment, and Sustainability at the University of British Columbia in 2003. His thesis focused on regional and local effects of exotic plant invasion in beach vegetation of Vancouver Island, BC. He wrote the COSEWIC status report for the Sand-verbena Moth, an endangered Copablepharon moth found in sand dunes of the Strait of Georgia, BC. He is also studying three other Copablepharon species (C. grandis, C. viridisparsa, C. absidum)found in sparsely vegetated sandy habitats in the Canadian prairies, as well as Taylor’s Checkerspot, an endangered butterfly in coastal BC.
Gary G. Anweiler is a research associate at the University of Alberta Strickland Entomological Museum. He has extensive experience studying Noctuid moths in western Canada, and has authored and co-authored 5 Draft Status reports on western Canadian noctuid moths for COSEWIC.
The following people are acknowledged and thanked for providing information that was used in the preparation of this report or assistance in undertaking field sampling: Jim Troubridge (Agriculture and Agri-Food Canada), Lars Crabo (Bellingham, WA), Jennifer Heron (BCEnvironment), Todd Golumbia (Parks Canada Agency), Metro Vancouver Parks, Bob Allan (Department of National Defence, CFBComox), BC Parks, and Parks Canada. Jim Troubridge kindly identified all specimens captured during the course of this work. Rob Cannings (RBCPM) and Karen Needham (UBC) kindly provided label data for specimens of A. edwardsii in their respective institutional collections. Michael Bradstreet and David Fraser are thanked for providing useful information on the BC habitat of this species.
This report was prepared with funding from Environment Canada.
- Crabo, L. Entomologist, Bellingham, WA.
- Heron, Jennifer. Biologist, BC Ministry of Environment, Vancouver, BC.
- Lafontaine, J. D. Research Scientist, Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, ON.
- McCabe, T.Curator of Entomology, State Entomologist, New York State Museum, New York, NY.
- Troubridge, J. T. Manager, Insect Collection, Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, ON.
The following collections were contacted or visited:
- Canadian National Collection (CNC) of Insects, Acari and Nematodes (contact: Jim Troubridge).
- Royal British Columbia Museum – RBCPM Victoria (contact: Rob Cannings).
- George J. Spencer Entomological Museum at the University of British Columbia (Contact: Karen Needham).
- Jim Troubridge, private collection [now divided between the CNC and UASMcollections)
- Lars Crabo, Bellingham WA - private collection
- UASM Edmonton (contact D. Shpeley)
- Date Modified: