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Recovery Strategy for the Island Blue* (Plebejus saepiolus insulanus) in Canada (Proposed)


Appendix 1. Executive Summary

Greenish Blue insulanus subspecies (Plebejus saepiolus insulanus Blackmore) is a subspecies of the Nearctic butterfly species P. saepiolus (Boisduval), the Greenish Blue, in the family Lycaenidae, which includes the blues, hairstreaks, and coppers. Seven subspecies of P. saepiolus are taxonomically described, two of which occur in British Columbia (B.C.): Greenish Blue insulanus subspecies, and P. saepiolus amica (W.H. Edwards). Greenish Blue insulanus subspecies is endemic to southern Vancouver Island, BC. The amica subspecies occurs from Yukon to Labrador and south through the mountains of California and Arizona (Layberry et al. 1998). It occurs throughout B.C. except on the coast (Guppy and Shepard 2001).

The most recent records of Greenish Blue insulanus subspecies are from Mount Malahat (1979), Mount Arrowsmith (1962, 1963), and Mount Finlayson (1960). Although the subspecies has not been recorded since 1979, surveys of potential habitat are incomplete and unconfirmed sightings are periodically reported. No extant population is known at this time.

Historic records of Greenish Blue insulanus subspecies are from disturbed habitats including roadsides, old campgrounds, clover banks along open streams, and similar habitats. The most recent records are from higher elevations including subalpine areas. Clovers, the apparent host plants, require continual moisture and sunlight. It is unknown if Greenish Blue insulanus subspecies can subsist on non-native clover species, although eastern populations of the amica subspecies do. Other subspecies of Greenish Blue are typically found in open areas with clovers, such as bog edges, woodland openings, and mountain meadows.

Potential threats to Greenish Blue insulanus subspecies include the introduction and encroachment of invasive plants that threaten native clover populations throughout the known range of the butterfly. Greenish Blue insulanus subspecies may not be able to use non-native clovers; presence of non-native clovers may also be detrimental to the survival of this butterfly as these species may displace native clovers. At low elevations in Garry oak and associated ecosystems, urban and rural land conversion, development pressure, and recreational use also threaten Greenish Blue insulanus subspecies habitat. The effects of climate change on Greenish Blue insulanus subspecies are unknown although considered a potential threat to the recovery of this butterfly.

Based on its taxonomic status as assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), no populations of Greenish Blue insulanus subspecies are known and recovery is not feasible at this time. If a population is located, recovery is possible through the current framework for species protection in British Columbia. Inventory of potential habitat will continue.

The recovery goal is to confirm the presence or absence of Greenish Blue insulanus subspecies within the species historic range in Canada, and protect1 any extant population(s) if found. The recovery objectives are to (1) survey all historical sites and areas of potential habitat and locate any existing population(s) of Greenish Blue insulanus subspecies by 2017; and (2) to implement habitat protection1 and threat mitigation for any populations located by 2017, using stewardship activities and other mechanisms.


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