Rare Species Guide

  Basis for Listing

The subspecies varuna of Uhler's Arctic (Oeneis uhleri varuna) occurs in the prairie provinces of Canada from Manitoba to British Columbia and south through Montana and the Dakotas to western Nebraska. Other subspecies occur in the Yukon and Northwest Territories and in the Rocky Mountains southward to northern New Mexico (Layberry et al. 1998; Lotts and Naberhaus 2017). Minnesota is on the southeastern fringe of the species' range.

Uhler's Arctic, also known as the Rocky Mountain Arctic, was first documented in Minnesota in 1965. Repeated observations in a large dry prairie site in Clay County confirmed a breeding population there (Red River Prairie Subsection). The species was also reported in 1968 from a single site each in Mahnomen and Rock counties, but confirming specimens are not available from either of these sites. Presumably, this butterfly was never common in the state even before prairie destruction, as its dry prairie habitat was a minor component of the prairie landscape. Most dry prairie in Minnesota has been destroyed by overgrazing, conversion to cropland, or aggregate mining; and today, potential habitat for the butterfly is rare (Minnesota’s Remaining Native Prairie). Much of the habitat where the one breeding colony occurs is threatened by overgrazing and gravel mining. The small size of this colony, and its isolation, make it highly susceptible to extirpation. For these reasons, Uhler's Arctic was listed as an endangered species in Minnesota in 1984. The single confirmed breeding population in Clay County has not been relocated in many years and is now considered likely extirpated.

  Description

Uhler's Arctic is a medium-sized butterfly with a forewing length (base to apex) of 2.3-2.7 cm (0.9-1.1 in.); the wings are somewhat elongate. Females are slightly larger than males and have more rounded wings. The sexes are similar in color and markings. Beneath, the hind wing and normally exposed tip of the forewing are pale gray, coarsely and intricately striated with dark brown. The striations are darker in the basal half of the hind wing. There is an arc of dark eyespots near the outer margin of the hind wing and again on the forewing; the size and number of these spots is variable. Above, the butterfly is orange-brown with the eyespot arcs repeated. The underside pattern is faintly visible through the orange. The butterfly rests with its wings closed vertically above its back, exposing only the cryptically marked undersides, which camouflages it very well among dry grass litter in the prairie.

There is no closely similar butterfly in the habitat of Uhler's Arctic in Minnesota. The Common Ringlet (Coenonympha california), another member of the subfamily Satyrinae that flies in the same habitat and at the same time, has a superficial resemblance to Ulhler's Arctic when glimpsed in flight. However, the Common Ringlet is a smaller butterfly with rounded wings, and the underside is an olivaceous gray without dark striations. Eyespots are nearly absent both above and below.

  Habitat

The habitat of Uhler's Arctic subspecies varuna in Canada is described as sandy prairie, lightly grazed areas, and open woods, where it prefers bunchgrass dominated hilltops and ridges (Layberry et al. 1998). In Minnesota, the one breeding colony occurred in dry prairie on sandy, gravelly crests and slopes of former shorelines of Glacial Lake Agassiz. Mid-height and short grasses such as little bluestem (Schizachyrium scoparium), needle-and-thread grass (Hesperostipa comata), junegrass (Koeleria macrantha), and blue grama (Bouteloua gracilis) are major components of this prairie.

  Biology / Life History

Uhler's Arctic adults emerge in late May and early June, and their flight is over by the end of June. Larval food plant preferences are unreported, though all other members of the genus whose host plants are known feed on grasses or sedges (or both). Far northern and alpine populations probably require two years to complete larval development (Scott 1986), but this is unlikely in Minnesota. Overwintering occurs as a partially grown larva, and pupation occurs in a cell just under the soil (Scott 1986). Adults are not often observed nectaring, but yellow composites (Asteraceae) are reportedly favored (Marrone 2002). Ragwort (Packera spp.) was sometimes visited at the Clay County site (personal observation). Males are reported to seek mates by hovering several meters above the grass (Layberry et al. 1998). Nothing is known about dispersal tendencies in this butterfly.

  Conservation / Management

The small size of Minnesota's colony of Uhler's Arctic likely made it highly susceptible to extirpation. This could result from natural events (such as severe drought or hailstorms) or human caused ones (such as insecticide application) as well as from the vagaries of normal population processes (for example, by chance all adults in one generation are males). Loss of genetic diversity in a small isolated population is also a threat. The nearest known colonies are in North Dakota on the other side of the intensively farmed Glacial Lake Agassiz lake plain, making immigration to the Minnesota population extremely unlikely. The larval stage of Uhler's Arctic is probably highly sensitive to fall and spring prairie fires. Pupation in the soil may afford some protection from spring burns to this developmental stage. Fires in the favored habitat will generally be on the cool side, as fuel loads are relatively low.  How the butterfly responds to haying is not known, though much of the prairie in the Clay County site was hayed in the late summer in the past. Uhler's Arctic does not appear to tolerate heavy grazing (Klassen et al. 1989; Layberry et al. 1998). The largest single tract within the Clay County site is a privately owned ranch, and the butterfly has not been observed within it. Reduction of grazing pressure on the drier prairie within the ranch would probably benefit the butterfly.

  Conservation Efforts in Minnesota

An intensive survey of the Clay County population was conducted in 1985 to determine where Uhler's Arctic occurred within the site (Braker 1985). The Minnesota DNR supported survey efforts in 1987 and 1991 to find new locations and update information for known locations, but no observations have been reported in Minnesota since 1985. Guidelines for protecting prairie butterfly populations within a fire-management program are employed by the major stewards of Uhler's Arctic habitat in Minnesota, and efforts have been made to educate other land managers in the state.

  Authors/Revisions

Robert P. Dana, Ph.D. (MNDNR), 2025
(Note: all content ©MNDNR)

  References and Additional Information

Klassen, P., A. R. Westwood, W. B. Preston, and W. B. McKillop. 1989. The butterflies of Manitoba. Manitoba Museum of Man and Nature, Winnipeg, Manitoba. 290 pp.

Layberry, R. A., P. W. Hall, and J. D. LaFontaine. 1998. The butterflies of Canada. University of Toronto Press, Toronto, Ontario. 280 pp. + color plates.

Marrone, G. M. 2002. Field guide to butterflies of South Dakota. South Dakota Department of Game, Fish, and Parks, Pierre, South Dakota. 478 pp.

Opler, P. A., H. Pavulaan, R. E. Stanford, and M. Pogue, coordinators. 2006. Butterflies and moths of North America: Uhler's arctic (Oeneis uhleri). Bozeman, Montana: NBII Mountain Prairie Information Node. . Accessed 20 July 2006.

Royer, R. A. 1988. Butterflies of North Dakota: an atlas and guide. Science Monograph Number 1, Minot State University, Minot, North Dakota. 192 pp.

Scott, J. A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California. 583 pp.

Swengel, A. B. 1998. Effects of management on butterfly abundance in tallgrass prairie and pine barrens. Biological Conservation 83(1):77-89.