Eastern persius duskywing: COSEWIC assessment and status report: appendices

Population Sizes and Trends

Suitable habitat for breeding E. p. persius has suffered dramatic declines over the last 100 years. Erynnis p. persius is considered extirpated in Maine and is probably extirpated in Maryland, New Jersey and New York. If it ever occurred in Illinois, Iowa, West Virginia, Vermont or Tennessee, it is probably extirpated in those states also. Erynnis p. persius is considered to be declining rapidly in the United States and has disappeared from most of its previous range since the late 1950s (NatureServe Explorer 2001). Across its range, habitat change and insecticide spraying are blamed for its demise (D. Schweitzer, pers. comm., 2002). In most jurisdictions where it is still extant, the skipper is considered critically imperilled (Table 1), and in its stronghold in Michigan, it is rare and considered to be Threatened. The Nature Conservancy reports that only 25 or so extant occurrences of E. p. persius are known across the United States (D. Schweitzer, pers. comm., 2002).

Canadian populations of E. p. persius were restricted to southwestern Ontario, where no individuals have been seen or collected in at least 18 years, despite recent survey efforts at the three areas where, based on prior consultation with expert botanists and entomologists, the likelihood of finding E. p. persius was the greatest (Appendix 2). Prior to that, little was known regarding Canadian populations, which were reliably reported sporadically over the previous ten to fifteen years from only two locations. The demise of this subspecies in Canada largely occurred before it was even known to occur there, and was likely caused by destruction, fragmentation and isolation of suitable habitat. Habitat loss, degradation and fragmentation have continued in southern Ontario since the skipper’s apparent disappearance. Despite recent efforts to restore habitat for this subspecies, L. m. samuelis and C. irus, there is very little chance E. p. persius still occurs in Canada.

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