endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (<100-250 square km (less than about 40-100 square miles)) Restricted to the Sierra Nevada at high altitudes, mainly above 9000', between Tuolumne and Tulare Counties, California (Ferris, 1988; Opler, 1999). Northernmost point of distribution is near Tower Peak at the northern boundary of Yosemite National Park (Opler, personal observation).

Comments: Moist alpine and subalpine meadows surrounded by low shrubs including those of the caterpillar host plants shrub willow or dwarf billberry (VACCINIUM CESPITOSUM)(Garth and Tilden, 1963; Scott, 1986; Opler, 1999).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Comments: Caterpillars eat the leaves of shrub willow or dwarf billberry (VACCINIUM CESPITOSUM)(Garth and Tilden, 1963; Scott, 1986; Opler, 1999). Adults nectar at various low flowers.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

10,000 to >1,000,000 individuals

Comments: Adults have a single flight in July and August (Ferris, 1988). Winter is passed by young caterpillars. The possibility exists that as for many alpine and subalpine species, two years may be necessary to complete the life cycle.

United States

Rounded National Status Rank: N2 - Imperiled

Rounded Global Status Rank: G2 - Imperiled

Reasons: Restricted to high alpine meadows of California's Sierra Nevada. Thus a very limited range. . In general common at high enough altitudes within this tiny range. Some occurrences are protected. Likely to be vulnerable to climate change given shortage of higher refugia and limited range.

Global Short Term Trend: Relatively stable (=10% change)

Global Long Term Trend: Unknown

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Summer cattle grazing of US Forest Service lands may be a threat, but usually not so high in elevation. Trampling of meadows by domestic livestock and hikers. Introduction of alien weeds is a less serious threat. Climate change probably is the greatest current threat. This butterfly is already confined to high altitudes.

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: National Park in part, USFS other parts.