Rare Species Guide

  Synonyms

Erebia disa mancinus

  Basis for Listing

The taiga alpine occurs across northern North America from Labrador to Alaska, but its only occurrence in the contiguous United States is in Minnesota, where it is known from only a handful of localities in a small area in the northeast part of the state. Recent surveys in the extensive Glacial Lake Agassiz peatlands have not discovered any occurrences there, suggesting that it has highly specialized habitat requirements. Because of the small number of known locations, the taiga alpine is vulnerable to habitat destruction and catastrophic events. For this reason, it was listed as a special concern species in Minnesota in 1984. Because its occurrence in Minnesota is at the southern limit of its range, this species may now be highly vulnerable to climate change.

  Description

The taiga alpine is a medium-sized dark brown butterfly with rounded wings. Wingspan is 3.5-4.3 cm (1.4-1.7 in.). The sexes are similar in size and markings. The row of black eye spots haloed by orange in the outer part of the dark brown forewing is distinctive. The red-disked alpine (Erebia discoidalis) is similar in size and also dark brown, but instead of a band of spots there is a large reddish-brown patch on the forewing. This species flies earlier than the taiga alpine, and favors open habitats. The Jutta arctic (Oeneis jutta) often flies in the same habitats and at the same time as the taiga alpine, but it has longer, more pointed wings and is generally a lighter, grayer shade of brown. There are eyespots on the hind wing as well as the forewing, and the eyespot haloes are yellow rather than orange. The jutta arctic usually flies in a fast, jerky manner, while the taiga alpine has a slow, gently bobbing flight.

  Habitat

In Minnesota, the taiga alpine appears to favor black spruce (Picea mariana) bogs and swamps where pole-like black spruce trees (8-10m) form a park-like environment, with small bushy trees dotting the understory (K. Johnson, pers. comm.). Tamarack (Larix laricina) is usually absent. Labrador tea (Rhododendron groenlandicum) dominates the shrub layer, which also includes various ericaceous species. Sphagnum mosses (Sphagnum spp.) form a carpet in which three-leaved false Solomon's seal (Maianthemum trifolium), three-fruited bog sedge (Carex trisperma), and few-flowered sedge (Carex pauciflora) are common herbs. Bog willow (Salix pedicellaris), bog birch (Betula pumila), and creeping sedge (Carex chordorrhiza) are sometimes present.

This type of habitat is abundant in northern Minnesota, making the very restricted distribution of the butterfly an enigma. In Canada, where it is more common and widespread, it occurs in a broader range of habitats, most commonly in open black spruce-sphagnum bogs (Layberry et al. 1998), although the reported habitat in Manitoba and Quebec bears much similarity to that in Minnesota (Klassen et al. 1989; Layberry et al. 1998).

  Biology / Life History

The immature stages are unknown. Some Manitoba populations have records only from alternating years, strongly indicating that development from egg to adult takes 2 years (Klassen et al. 1989). Field work in Minnesota suggests that this may be true here also: some sites appear to have adults only in even-numbered years, others only in odd-numbered years, and still others every year (K. Johnson, pers. comm.). Odd-numbered years seem to be favored, but more field work is needed to clarify this. Adults have been recorded from June 3 to June 26 in the state, with peak flight around mid June, and lasting perhaps 2-3 weeks.

The larval food plants are unknown, but these are undoubtedly grasses or sedges, as this is generally true of species in the subfamily Satyrinae to which it belongs. Field observation in Minnesota suggests that three-fruited bog sedge and few-flowered sedge are the most likely candidates (K. Johnson, pers. comm.). Adults are rarely observed to take floral nectar, but they sometimes sit on damp soil, including gravel roads near their habitat, where they probably take up moisture and dissolved minerals. Carrion, animal feces, and sap flows, often used by members of the subfamily Satyrinae, are other likely adult food sources.

  Conservation / Management

The taiga alpine is listed as a special concern species in Minnesota primarily because it is apparently rare and limited to a small geographic area. Habitat alteration or destruction could easily threaten the continued occurrence of the species in Minnesota, but because so little is known about its biology, much is unknown about the specific nature of the changes that would threaten the species. As this butterfly is at the southern limit of its range, where it is dependent on local areas of colder conditions, global warming is clearly a long-term threat. Disturbances that accelerate changes to the forest forced by climate warming should be avoided. Disruption of the hydrology of its peatland habitats is one such disturbance, especially if the result is greater susceptibility to severe forest fires. Clearcutting of occupied habitat will also have great potential for harm; the effects of selective harvest cannot be predicted on the basis of present knowledge. Application of insecticides to the species' habitat would certainly be a threat, as would the use of herbicides that affect graminoid plants.

  Conservation Efforts in Minnesota

Data on known occurrences of the taiga alpine are utilized in reviewing various activities for environmental impact, notably the application of insecticides and herbicides. These records are also available to forest managers. A significant area known to support this butterfly is protected within the Minnesota DNR's Sand Lake Peatland Scientific and Natural Area. Additional survey work is needed to determine the full range of this species in Minnesota and its distribution and abundance within that range.

  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.

NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia. . Accessed 3 June 2008.

Opler, P. A., H. Pavulaan, R. E. Stanford, and M. Pogue, coordinators. 2006. Butterflies and moths of North America: Taiga alpine (Erebia mancinus). Bozeman, Montana: NBII Mountain Prairie Information Node. . Accessed 20 July 2006.