Species Status Assessment for the Sand Verbena Moth (Copablepharon Fuscum)
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Species Status Assessment for the Sand Verbena Moth (Copablepharon fuscum) Version 1.0 2019 U.S. FISH AND WILDLIFE SERVICE EXECUTIVE SUMMARY This document presents the species status assessment (SSA) for the sand verbena moth (Copablepharon fuscum), completed to characterize the species’ overall viability by using the three conservation biology principles of resiliency, redundancy and representation. We identify the species’ ecological requirements for survival and reproduction at the individual, population, and species levels, and describe risk factors influencing the species’ current and future condition. The sand verbena moth is a narrow endemic that primarily occupies nearshore areas around the Salish Sea in southern British Columbia, Canada, and northern Washington in the United States, with the exception being a single detection on the west coast of Vancouver Island, in British Columbia. Since the species was first discovered in 1994, it has been detected at 11 sites; six in Canada and five in the United States. Searches/surveys for sand verbena moth have been inconsistent in frequency, scope, and intensity, and have only provided information on species presence (e.g. positive and negative detections); the limited demographic information available for the species prevents the development of abundance estimates or population trends for the sand verbena moth. Species viability relies on interconnected healthy populations with habitat that provides for feeding, sheltering, and protection from predators, but we don’t have information to confirm dispersal between the disparate detection sites for the sand verbena moth. The sand verbena moth completes its entire life cycle on and around the yellow sand verbena plant (Abronia latifolia). The sand verbena moth mates on the plant, lays its eggs in the flowers, and feeds on the leaves and flowers of the plant during its developmental stages, shelters under it from early instar through pupation, and provides pollination services to it as a winged adult feeding on the flowers’ nectar. Resilient populations of sand verbena moth should: (1) be of sufficiently large size; (2) have dense patches of flowering A. latifolia with leaf cover totaling at least 400 m2 (0.10 ac), in loose, open sand; (3) be within maximum dispersal distance of each other; and (4) be where 30-year normal precipitation is below 1950 mm (77 in) and 30-year normal temperatures is above 7.47 °C (45 °F). Though no data exists on historical abundance and distribution of the sand verbena moth that we can compare to current condition, best available information suggests that the species has likely been negatively affected by some risk factors. For this assessment we analyzed the effects on the sand verbena moth by the following: habitat loss, modification, and fragmentation (from erosion, inundation from sea level rise and debris deposition, development, recreational/human use, and invasive plants and animals) and predations by bats, red foxes, and tiger beetles. Analysis of Current Condition Of the 11 sites with detections of the sand verbena moth there are six where it has been detected within the last five years; three in British Columbia, Canada (Goose Spit, Island View Beach/Cordova Spit, and James Island) and three in Washington in the United States (American Camp/Cattle Point, Deception Pass, and Fort Worden State Park). There was more information regarding recent detections at these six sites than for the other five, so we refer to these six sites as potential populations. Recent monitoring data (Fleckenstein et al. 2018a/b) for American Camp/Cattle Point and Fort Worden provides confidence that the species currently persists at these two sites in a self- sustaining way, meaning that the recruitment rate at these sites appears to consistently meet or exceed the mortality rates on average over time. All six of the sites with potential populations have 30-year normal precipitation below 1950 mm (77 in) and 30-year normal temperatures above 7.47 °C (45 °F) (see discussion in Section 3.0). The habitat at all six of these sites is currently affected by several risk factors on an ongoing basis, likely degrading the suitability of habitat over time. These habitat risk factors include erosion, inundation by sea water and deposit of woody debris, recreation and human use, development, and invasive plant species. Sand verbena moths at all of these sites also likely experience some level of predation by red fox, tiger beetles and bats, or other effects from invasive animal species, however, we have no information to determine whether these two factors are currently causing population-level effects at any of the sites. We determined ratings of current site condition based on the criteria summarized in the following table: Rating Categories Mostly Somewhat Compromised Higly Criteria Stable Stable Compromised Compromised ≥ 400 m2 (0.04 ha or 4,306 ft2) total leaf cover of Abronia X X X X X X X X latifolia Patch density ≥ 25 percent leaf cover of Abronia latifolia, high X X X X flower production May –July Both 30-year normal precipitation below 1950 mm (77 in) and 30-year normal X X X X X temperatures above 7.47 °C (45 °F) Low X Moderate X Low OR X X Site Moderate Vulnerability High X X X X Low OR Moderate OR X High American Camp/Cattle Point has an overall site condition rating of ‘Somewhat Compromised.’ The site contains greatest area of Abronia latifolia of any of the sites and it occurs in dense patches, but ongoing erosion in the dunes and in areas along the bluffs puts portions of the habitat at risk. Additionally, invasive plant species are exerting a strong negative effect on the A. latifolia across the site. Regardless, the records of sand verbena moth detections at the site suggests it currently harbors a robust, self-sustaining population of sand verbena moths (e.g. recruitment rate at the site appears to consistently meet or exceed the mortality rate on average over time). The other two sites in the United States with potential populations of sand verbena moth also have overall site condition ratings of ‘Somewhat Compromised.’ When last surveyed, Fort Worden had over 400 m2 (0.04 ha or 4,306 ft2) total leaf cover of Abronia latifolia but with densities of less than 25 percent leaf cover in most patches. Deception Pass has high pressure from recreation at the site and moderate to high competition with invasive plant species. The condition of the three Canadian sites with potential populations (Goose Spit, James Island, Island View Beach/Cordova Spit) is unknown due to lack of information on the total leaf cover, leaf density, and flower density of Abronia latifolia. Information from the British Columbia Conservation Data Centre suggests that there may be ≥ 400 m2 (0.04 ha or 4,306 ft2) of A. latifolia at these sites, but we received no information regarding total leaf cover and quality of the habitat. The current condition of sites with a potential population is summarized in the table below: ≥ 400 m2 Patch density Both 30-year normal total leaf ≥ 25 percent leaf cover of precipitation below 1950 Overall site cover of Abronia latifolia, , with mm (77 in) and 30-year condition Abronia high flower production normal temperatures Site Site Name latifolia from May-July above 7.47 °C (45 °F) Vulnerability CANADA Unknown Goose Spit no data no data yes High (missing data) Island View Unknown Beach and no data no data yes Moderate (missing data) Cordova Spit Unknown James Island no data no data yes Moderate (missing data) UNITED STATES American Camp (AC) Somewhat yes yes yes High and Cattle Compromised Point (CP) Deception Somewhat Pass State yes no yes Moderate Compromised Park Fort Worden Somewhat yes no yes Moderate State Park Compromised Redundancy for the sand verbena moth appears to be limited to six potential populations, although the lack of information regarding presence/absence at other sites, trends in occupancy and abundance over the known range of the species, and historical redundancy make it difficult to judge whether our current estimate of low redundancy is accurate. Specifically, there has been inconsistent or little monitoring of sites where the sand verbena moth has been detected over the past 24 years. Although we have evidence to suggest that sand verbena moth populations may occur at six sites range-wide indicating low redundancy, without recent surveys for almost half the sites where the sand verbena moth has been previously detected, our estimate of redundancy is very uncertain. Our capacity to estimate representation for the sand verbena moth is limited, but we presume that it is low, based on the minimal information we have. The best available information does not indicate any behavioral or morphological diversity in the sand verbena moth. Additionally, little ecological diversity can be identified because the sand verbena moth inhabits a narrow ecological band and is restricted to a single host plant in sandy coastal habitat with maritime temperatures that exhibit little fluctuation. There has been little genetic analysis of the sand verbena moth conducted to date and there are no data to describe the genetic representation of the species range wide. There have been no studies conducted to characterize the dispersal distance of the sand verbena moth. The sand verbena moth has been observed to fly strongly in winds between 5 and 15 km per hour and some related moth species have been documented to fly great distances, but the sand verbena moth has rarely been detected greater than 25 m (82 ft) from Abronia latifolia. There at least one report of indicating that a sand verbena moth dispersed at least 475 m (1558 ft) (Hudson 2018, in litt.; Hudson 2019, in litt.). The sites where the sand verbena moth has been detected are separated by distances that may be greater than the sand verbena moth can disperse; if this is indeed the case it would suggest that most sites have low connectivity necessary to facilitate genetic exchange, and therefore the sand verbena moths at the sites are likely to exhibit low genetic diversity.