Example of a juniper hairstreak butterfly species.
Moderate
The population of the juniper hairstreak (Columbia Basin segregate) in Washington is low and the trend is unknown. This lycaenid butterfly species is recognized as a state "Species of Greatest Conservation Need" due to its rare and restricted hostplants [food for caterpillars (larvae)] and habitat types, small number of isolated populations, highly limited range and distribution, and threats to its habitat. Research is needed on this species to understand its life history and quantify specific habitat requirements including vegetation structure, food plant size and density, and key habitat features.
Description and Range
Physical description
The Lycaenidae butterfly family consists of small and often brightly colored species with the common names: copper, hairstreak, elfin, and blue. Adult juniper hairstreaks have a wingspan of just over one inch. Males and females differ slightly in color, with the upper side of males being a dull red-brown while females are tawny in color. Undersides range from dull red to tawny color with a weak white sub-terminal band and strong violet tint on the hindwing. Larvae (caterpillars) are highly camouflaged and resemble the juniper shoots on which they feed.
Ecology and life history
The juniper hairstreak (Columbia Basin segregate) inhabits low to middle elevation shrubsteppe where there are stands of juniper. Western juniper (Juniperus occidentalis), a short evergreen tree, is the species’ most common hostplant. Other Cypress family species, including Rocky Mountain juniper and various ornamental species, are also utilized as hosts.
This lycaenid butterfly completes a single life cycle annually (univoltine). All lycaenids are sedentary butterflies and do not migrate; instead, the species inhabits sites year-round (as egg, larva, pupa and adult), typically moving within only a few hundred yards of their natal locations. Adults emerge from their chrysalids (pupae) during species-specific time periods; the juniper hairstreak’s adult period is April through May.
The males begin emergence first, followed by females; late season individuals are primarily or solely females. Nectaring occurs on spring flowering shrubsteppe plants, such as desert parsley and buckwheat, that are in close proximity to juniper hostplants. Both males and females feed by using their long proboscis to sip floral nectar. Males of most species require salts, which they obtain from evaporated puddles and moist soil and animal urine and feces.
Male lycaenids seek mates using patrolling patterned flight or perching on vegetation in select spots and darting out to inspect passing butterflies. Male hairstreaks perch on juniper branches and defend territories, waiting for females to arrive in early April to late May. Females search for egg-laying sites by slowly flying and hovering above hostplant vegetation, and then landing and crawling to inspect vegetation before depositing eggs singly on the tips of juniper branches, where larvae will feed.
Larvae are slug-like in appearance and highly camouflaged in their host species. Many lycaenid larvae engage in mutualistic relationships with ants, known as myrmecophily, which typically consists of ants tending and milking larvae, obtaining nutrition in the form of a nectar-like substance (honeydew) in the process, and also protecting larvae from predators and parasitoids; in some situations, the ants move butterfly larvae or pupae into ground chambers, including their nests. The overwintering stage varies by lycaenid species: juniper hairstreak overwinter as pupae.
Geographic range
Hairstreak butterflies occur in variants across the entire United States. The species are non-migratory and generally spend their life in one small area. Their habitat is expanding in eastern Oregon, where western juniper is encroaching on native grasslands and shrublands.
The distribution of the juniper hairstreak (Columbia Basin segregate) is limited in part by a combination of its dependence on rare hostplant occurrence within rare habitat types. In Washington, its distribution and abundance is characterized by small numbers of small, isolated populations. The species' overall range is scattered in the central Columbia Basin—in southeast Washington and northeast Oregon. In Washington, occurrence has been documented in Asotin, Columbia, Douglas, Franklin, Garfield, Grand and Klickitat counties. The Juniper Dunes Wilderness (Bureau of Land Management) in Franklin County is one of the few Washington locations where the species can reliably be found. In 2017, a new population was identified in Klickitat County.
For a range-wide map of conservation status and distribution of juniper hairstreak species, check out NatureServe Explorer.
Climate vulnerability
Sensitivity to climate change
Moderate
Temperature and precipitation likely affect larval forage periods. The sensitivity of juniper hairstreak is likely largely driven by climate-driven shifts in its larval host plant, western juniper. Western juniper is shade-intolerant, and fire helps prevent succession to conifer forest types in juniper stands. However, western juniper is also fire-intolerant, typically experiencing high fire mortality but still able to recolonize post-fire. Increasing fire frequency and severity may help maintain juniper hairstreak habitat by preventing succession, but can also lead to short-term habitat loss if fire burns in current habitat areas. Warmer and more xeric conditions may favor the expansion of western juniper woodland habitats, potentially benefitting juniper hairstreak.
Exposure to climate change
Moderate
- Altered fire regimes
Conservation
Conservation Threats and Actions Needed
- Resource information collection needs
- Threat: Lacking information on current status of known sites and distribution
- Action Needed: Inventory and status assessment
- Fish and wildlife habitat loss or degradation
- Threat: Juniper woodlands are threatened with development, unsustainable grazing practices, ORV use, etc.
- Action Needed: Habitat management planning that recognizes importance of juniper woodlands
See the Climate vulnerability section for information about the threats posed by climate change to this species.
Juniper habitat has been expanding in some areas of the West due to factors including fire suppression and grazing, but habitat in the Columbia Basin has generally decreased due to wildfire, conversion of grasslands to agriculture, and wind and solar power development; however, pockets of protected habitat remain in dissected canyons and public land areas.
Although junipers have been used extensively in conservation plantings to stabilize streambanks and provide cover for gamebirds, the non-migratory and sedentary nature of the juniper hairstreak limits dispersal potential to colonize new habitat. Oregon populations have expanded with the invasion of juniper into grass and shrublands but were found to retract after juniper control (fire and mechanical removal).
Invasive plants such as cheat grass and yellow star-thistle pose a significant threat by restricting the flowering species on which adult butterflies feed.
Our Conservation Efforts
In 2017, WDFW sponsored an agency and citizen science project to survey historical detection areas and other areas with suitable habitat. Two of three historical sites were found to be destroyed by fire, and one new occurrence was documented in Klickitat County, with a repeat detection at that site during surveys in 2019.
Resources
References
Ballmer, G. and G. Pratt. 1991. Quantification of ant attendance (Myrmecophily) of lycaenid larvae. Journal of Research on the Lepidoptera. 30(1-2): 95-112.
James, D. and D. Nunnallee. 2011. Life Histories of Cascadia Butterflies. Oregon State University Press, Corvallis. 447 pp.
Pyle, R.M. and C.C. LaBar. 2018. Butterflies of the Pacific Northwest. Timber Press. 461 pp.
Pyle, R. 1989. Washington butterfly conservation status report and plan. Washington Department of Fish and Wildlife, Olympia. 216pp.
WDFW publications
PHS Program
Other resources
- Xerces Society - Butterfly Conservation
- Butterflies of America – Columbia Basin Segregate Juniper Hairstreak