Boloria improba acrocnema

Overview

Discovered only in 1978 and described as a new species in 1984, this butterfly is endemic to the high alpine meadows of the San Juan Mountains in southwestern Colorado. Intensive collecting pressure, improper grazing by domestic livestock, periods of prolonged drought conditions, mining activity, and an increase in alpine recreation coincided with a dramatic population decline and led to its listing as an endangered species under the U.S. Endangered Species Act in 1982.

The Uncompahgre fritillary butterfly lives in patches of snow willow (Salix spp.) at high elevations, and has very limited habitat, a small population size, and low genetic variability, which may affect long-term population stability. The species is susceptible to trampling by recreationists and grazing animals.

Description

The Uncompahgre fritillary (Boloria improba acrocnema) is in the Nymphalidae (brush-foot) family. It is a small butterfly with a wingspan of 1 1/8 to 1 3/8 inches (3 - 3.5 cm). The dorsal side of the wings is dull orange-brown, with darker shading toward the wing bases, and markings that appear faded and indistinct. On the ventral side of the hindwing the wing is dark orange-brown at base, providing a stronger contrast with the ivory white costa and ivory dash between costa and cell. The rest of the ventral surface is grayish.

Life History

These butterflies live in moist tundra with dwarf willows above 13,000 ft. Eggs are laid singly on stems of host plant dwarf willows (Salix arctica). The caterpillars eat the willows' leaves. Due to the short growing season at such altitudes, the butterflies require two years to complete development from egg to adult. Newly hatched caterpillars hibernate the first winter, before growing through two more instars during the summer and then passing a second winter as fourth instars. During the second, summer they complete development and emerge as sexually active adults.

Distribution

Believed to be broadly distributed near glacial margins during the Wisconsin glaciation, the Uncompahgre fritillary is now confined to small patches of habitat above 13,000 ft in the San Juan Mountains of southwestern Colorado where glacier-like environments have persisted from the Holocene to the present.

Conservation Status

Listing the species led to extensive studies to develop knowledge of its natural history, genetics and population trends, and prompted searches for new colonies. Prior to 1995, only two colonies of this butterfly were known to exist. Between 1995 and 2000, intensive inventory efforts by the Colorado Natural Heritage Program led to the discovery of eight additional colonies, with the most recent being discovered in 1998. Monitoring techniques are being used to estimate population sizes of the colonies. Preliminary studies with maps, aerial photos and ground surveys indicate that numerous areas have high potential for additional colonies.

Although there is much optimism with the discovery of these new populations, threats to this species still exist. Illegal collecting, increased recreation, and the possibility that global warming will result in an altitudinal retreat of habitat all continue to threaten colonies of this butterfly.

Conservation Needs

Necessary recovery actions include restricting collection of the butterfly, monitoring known populations and searching for new ones, and continuing data collection to determine if there are any other threats to the species.

Working with landowners

All known populations are on Forest Service and Bureau of Land Management land.

Education

Education sheets available at zoological facilities (e.g. zoos, aquariums, botanical gardens with butterflies, butterfly houses, natural history museums) or events at which BFCI partners participate are a valuable way to disseminate information about imperiled butterflies.

When schools and other youth organizations study biodiversity and species extinctions they typically use examples of charismatic megafauna (e.g. bald eagles) or exotic creatures from the tropics. However, vulnerable species found within the state or ecoregion in which students live provide an excellent opportunity to develop curricular materials with a direct link to the students' home region. In addition to classroom studies, students may be able to visit sites to see the butterflies, as well as talk to the scientists and land managers involved in the species' conservation.

Educational activities that school students and community members could do include:

• studying butterfly (insect) life stages;
• researching the special habitat needs of the Uncompahgre fritillary;
• corresponding or meeting with the biologists managing current Uncompahgre fritillary sites;
• visiting Uncompahgre fritillary sites during adult flight season;
• visiting captive breeding programs;
• assisting scientists with on-site habitat management;
• propagating and growing host plants for planting at butterfly sites or use in captive breeding programs; and
• writing letters to decision makers to ensure that the Uncompahgre fritillary receives adequate resources and protection.

Research

Efforts to monitor known populations and searches for new ones are ongoing.

Captive Rearing

Information was not available at time of publication.

Recovery Plan

USFWS, 1994. Uncompahgre Fritillary Recovery Plan (1.9MB pdf).

For more information

• USFWS Contact: Bettina Proctor, Partnerships Coordinator, Fish and Wildlife Service Office, P.O. Box 25486, Denver Federal Center, Denver, Colorado 80225, Phone (303) 236-8155, extension 259
• Colorado State University: Aaron Ellingson, are@lamar.colostate.edu

References and Resources

• Britten, H.B. and L. Riley. 1994. Nectar source diversity as an indicator of habitat suitability for the endangered Uncompahgre fritillary, Boloria acrocnema (Nymphalidae). Journal of the Lepidopterists' Society 48: 173 179.
• Britten, H.B., P.F. Brussard, and D.D. Murphy. 1994. The pending extinction of the Uncompahgre fritillary butterfly. Conservation Biology 8: 86 94.
• Ellingson A., C. Pague, S. Hoffman, and C. Sculley. 1996. Population Monitoring and Inventory of the Uncompahgre Fritillary (Boloria acrocnema). Report for the Colorado Natural Heritage Program, Fort Collins, CO. 43 pp.
• USFWS, 1994. Uncompahgre Fritillary Recovery Plan
• USGS Butterflies of Colorado Uncompahgre fritillary page
• USFWS Uncompahgre fritillary page

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Classification

Federal Endangered Species (Federal Register 56:28712; June 24 1991)

State Status

No state designation beyond the federal classification.

Range

CO

Critical Habitat

None designated

Acknowledgement

This profile was prepared by the Xerces Society for the Butterfly Conservation Initiative.