Palos Verdes Blue Butterfly (Glaucopsyche lygdamus palosverdesensis) 5-Year Review: Summary and Evaluation Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis). Photocredit: Jane Hendron, USFWS. U.S. Fish and Wildlife Service Carlsbad Fish and Wildlife Office Carlsbad, California January 09, 2014 2014 5-year Review for Palos Verdes Blue Butterfly 5-YEAR REVIEW Palos Verdes Blue Butterfly (Glaucopsyche lygdamus palosverdesensis) I. GENERAL INFORMATION Purpose of 5-year Reviews: The U.S. Fish and Wildlife Service (Service) is required by section 4(c)(2) of the Endangered Species Act (Act) to conduct a status review of each listed species at least once every 5 years. The purpose of a 5-year review is to evaluate whether or not the species’ status has changed since it was listed. Based on the 5-year review, we recommend whether the species should be removed from the list of endangered and threatened species, be changed in status from endangered to threatened, or be changed in status from threatened to endangered. Our original listing of a species as endangered or threatened is based on the existence of threats attributable to one or more of the five threat factors described in section 4(a)(1) of the Act, and we must consider these same five factors in any subsequent consideration of reclassification or delisting of a species. In the 5-year review, we consider the best available scientific and commercial data on the species, and focus on new information available since the species was listed or last reviewed. If we recommend a change in listing status based on the results of the 5-year review, we must propose to do so through a separate rule-making process defined in the Act that includes public review and comment. Subspecies Overview: The Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis) is endemic to the Palos Verdes Peninsula in Los Angeles County, California; it is a subspecies of the wide-ranging silvery blue butterfly (a species distributed throughout western North America). The Palos Verdes blue butterfly is differentiated from other subspecies primarily through geographic isolation, hostplant use, and the typical pattern of spots on the bottom side of its wings. The Palos Verdes blue butterfly was federally listed as endangered under the Act in 1980, due primarily to the threats of habitat destruction and small population size. Three populations were identified in the listing rule, and six more discovered over the next 2 years; however, all these historical populations were extirpated prior to 1994. The two currently remaining historical populations (only one is known to be extant for certain) were discovered in 1994 and 2001. There are three sites not known to be historically occupied that have undergone introduction of captive stock, only one is currently considered extant, and introduction was ongoing at that site through 2013. While conservation, management, and restoration of remaining habitats and population management have reduced the threats of habitat loss and small population size, these threats remain significant. Methodology Used to Complete This Review: This review was prepared by Alison Anderson at the Carlsbad Fish and Wildlife Office, following the Region 8 guidance issued in March 2008. We used status and survey information from experts and published peer-reviewed research, in particular The Urban Wildlands Group 2 2014 5-year Review for Palos Verdes Blue Butterfly and the Palos Verdes Peninsula Land Conservancy. We received no information relative to Palos Verdes blue butterfly from the public in response to our Federal Notice initiating this 5-year review. This 5-year review contains updated information on the subspecies’ biology and threats, and an assessment of information compared to that described in the 2008 status review. We focus on current threats to the subspecies pursuant to the Act’s five listing factors. This review synthesizes this information to evaluate the listing status of the subspecies and provide an indication of progress towards recovery. Finally, based on this synthesis and the threats identified in performing the five-factor analysis, we herein recommend a prioritized list of conservation actions to be completed or initiated within the next 5 years. Contact Information: Lead Regional Office: Larry Rabin, Deputy Division Chief for Listing, Recovery, and Environmental Contaminants, and Lisa Ellis, Fish and Wildlife Biologist, Region 8; 916–414–6464. Lead Field Office: Alison Anderson and Bradd Baskerville-Bridges, Carlsbad Fish and Wildlife Office; 760–431–9440. Federal Register Notice Citation Announcing Initiation of This Review: A notice announcing initiation of the 5-year review of this taxon and the opening of a 60-day period to receive information from the public was published in the Federal Register on May 25, 2011 (USFWS 2011, p. 30378). No information relevant to the Palos Verdes blue butterfly was received. Listing History: Federal Listing FR Notice: 45 FR 44939 (USFWS 1980) Date of Final Rule: July 2, 1980 Entity Listed: Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis), an insect subspecies Classification: Endangered State Listing The Palos Verdes blue butterfly is not listed by the State of California as endangered or threatened because insects are not covered under the California Endangered Species Act. Associated Rulemakings: Critical habitat was designated for the Palos Verdes blue butterfly on July 2, 1980, at the time of listing (USFWS 1980). Critical habitat consisted of three units on the western slope of the peninsula; Agua Amarga Canyon (40 acres (ac) (16 hectares (ha)), Frank Hesse Park (36 ac (15 ha)), and Palos Verdes Drive (15 ac (6 ha)). 3 2014 5-year Review for Palos Verdes Blue Butterfly Review History: The Service initiated 5-year reviews for the Palos Verdes blue butterfly in 1985 and 1991 (USFWS 1985; USFWS 1991); both status reviews were completed with no recommended change in status. The most recent 5-year review was initiated in 2007 and signed March 31, 2008 (USFWS 2008); we recommended no change in status. Subspecies’ Recovery Priority Number at Start of 5-Year Review: The recovery priority number for the Palos Verdes blue butterfly is 6 according to the Service’s 2013 Recovery Data Call, based on a 1–18 ranking system where 1 is the highest-ranked recovery priority and 18 is the lowest (USFWS 1983a, pp. 43098–43105; USFWS 1983b, p. 51985). This number indicates that the taxon is a subspecies that faces a high degree of threat and a low potential for recovery. Recovery Plan or Outline: Name of Plan or Outline: Palos Verdes Blue Butterfly Recovery Plan (Recovery Plan) Date Issued: January 19, 1984 Dates of Previous Revisions: N/A II. REVIEW ANALYSIS Application of the 1996 Distinct Population Segment (DPS) Policy: The Act defines “species” as including any subspecies of fish, or wildlife, or plants, and any distinct population segment (DPS) of any species of vertebrate. This definition of species under the Act limits listing as DPSs to species of vertebrate fish or wildlife. The 1996 Policy Regarding the Recognition of Distinct Vertebrate Population Segments under the Act (USFWS 1996, pp. 4722–4725) clarifies the interpretation of the phrase “distinct population segment” for the purposes of listing, delisting, and reclassifying species under the Act. The Palos Verdes blue butterfly is an invertebrate and is therefore not listed as a DPS. Information on the Species and its Status: Subspecies Description As described in the Recovery Plan (USFWS 1984, p. 2) Palos Verdes blue butterflies are morphologically distinguished from other subspecies Glaucopsyche lygdamus (Doubleday) by their size, wing color, and maculation (spotting) pattern. The Palos Verdes blue butterfly is a member of the family Lycaenidae. Males have a silvery-blue dorsal wing surface with a narrow black border, the female’s dorsal wing surfaces is a brownish-gray color. Males and females have a gray ventral wing surface with dark spots surrounded by white. The Palos Verdes blue butterfly wingspan is approximately 1 inch (25 millimeters (mm)) (Arnold, 1987, p. 203). 4 2014 5-year Review for Palos Verdes Blue Butterfly Subspecies Biology and Habitat Palos Verdes blue butterflies require suitable larval hostplants for oviposition and larval development. Astragalus trichopodus lonchus (coast locoweed) was once thought to be the exclusive larval hostplant; however, Palos Verdes blue butterfly larvae are now known to feed on Acmispon glaber (deerweed) (Mattoni 1994, p. 186). Both of these hostplants are naturally distributed within disturbed patches in coastal sage scrub (CSS) communities throughout the Palos Verdes Peninsula. Both host plant species invade cleared areas following disturbance. Mattoni et al.’s (2002, p. 13) model demonstrated the best predictors of Palos Verdes blue butterfly abundance are Acmispon glaber, Astragalus trichopodus, slope, and azimuth. Most adult butterflies were found at intermediate slopes facing north through east with higher numbers of host plants. Adults seem to respond to specific topoclimatic variables, and given the subspecies’ yearly spatial variation, different sites likely provide optimal conditions in different years (Mattoni et al. 2002, p. 13). Silvery blue butterflies (Glauchopsyche lygdamus) are known to use a variety of flowers as nectar sources, primarily Asteracae (composits, sunflowers; BAMONA 2013). The adult flight period is tied to hostplant flowering and generally occurs between late January and early May (Lipman et al. 1999, p. 4). Palos Verdes blue butterfly adults are thought to be relatively poor dispersers (Mattoni 1994, p. 185), and initial studies suggest that males are more likely to disperse among habitat patches than females (Lipman et al. 1999, p. 5). Oviposition (egg-depositing) occurs throughout the flight season, and eggs are deposited on the flowers or leaves of Astragalus trichopodus lonchus or Acmispon glaber. Spatial Distribution and Abundance Historically, Palos Verdes blue butterflies were known to occur throughout the coastal slope of the topographically diverse Palos Verdes peninsula in Los Angeles County, California.