Aeshna subarctica Walker, 1908
Basis for Listing
The Subarctic Darner (Aeshna subarctica) is a Holarctic species, occurring in the boggy regions of northern North America, throughout Europe and Eurasia, and into Japan. Minnesota has historical records from several counties including Roseau, Lake of the Woods, Koochiching, Beltrami, Pine, and Douglas (Odonata Central 2017). The Douglas County record, however, seems dubious due to a paucity of the proper habitats in that region. Confirmed records are from Cook, Lake, St. Louis, Carlton, Koochiching, Beltrami, Roseau, and Hubbard counties in the Laurentian Mixed Forest Province. Based on the few isolated populations of this species encountered in Minnesota, the species’ very specific habitat needs, and the potential threat of the eutrophication of its breeding waters, the Subarctic Darner was listed as a special concern species in 2013.
Wisconsin has also listed the Subarctic Darner as a species of special concern.
An average sized darner, at 7 cm (2.8 in.) total length, the Subarctic Darner is most easily recognized by its uniquely forward-bent thoracic stripes. There are often thin streaks visible between the two thoracic stripes and another thin streak possible in front of the forward stripe. The species has a thin but pronounced black facial stripe. Abdominal spots of this species are typical of the genus, showing the mosaic pattern of light spots on a dark background. Male claspers (upper terminal appendages) are of the paddle type, and the female cerci (terminal appendages) are longer than abdominal segments 9-10 combined (Paulson 2012).
The Subarctic Darner prefers swamps as well as acidic fen and bog pools, with well-defined moss edges (Dunkle 2000). In Minnesota, the Subarctic Darner occurs in northern poor fens and northern open bogs within acidic peatland systems.
Biology / Life History
The flight period of the Subarctic Darner is from early to mid-July through September (Dunkle 2000; Paulson 2009). Males are territorial only at low densities, typically flying low over open bog pools, investigating floating bog mats and emergent vegetation. Females oviposit at the pond margin in mosses or sedges. Adults feed in open areas until dusk (Dunkle 2000; Paulson 2009) and are indiscriminate feeders of flying insects. Very little is known about this species' larval life cycles or habits.
Conservation / Management
Although the peatland breeding habitats needed by the Subarctic Darner tend to be currently inaccessible and remote, there has been some recent activity hinting toward a renewed interest in peat mining in Minnesota. Such activity could severely threaten the survival of this species in mining areas. The breeding habitat is susceptible to degradation by any land use activity that changes the hydrology of the habitat or increases erosion or run-off.
It is assumed that global climate change will move the southern edge of the boreal biome to the north. This change could eliminate Subarctic Darners from the state.
Conservation Efforts in Minnesota
The designation of North Black River Peatland, Sand Lake Peatland, and Luxemburg Peatland as state Scientific and Natural Areas will play a large role in the conservation of this species. The non-profit Minnesota Dragonfly Society is looking for the Subarctic Darner (among many other species of Odonata) throughout Minnesota through surveys and educational workshops. These surveys are conducted by volunteers and are supported through an Enbridge Ecofootprint Grant through 2018.
Kurt Mead (MNDNR), 2018
(Note: all content ©MNDNR)
References and Additional Information
Abbott, J. C. 2006-2017. Odonata Central: An online resource for the distribution and identification of Odonata [web application]. <http://www.odonatacentral.org>. Accessed 21 March 2017.
Donnelly, T. W. 2004. Distribution of North American Odonata. Part I: Aeshnidae, Petaluridae, Gomphidae, Cordulegastridae. Bulletin of American Odonatology 7(4):61-90.
Donnelly, T.W. 2004. Distribution of North American Odonata. Part II: Macromiidae, Corduliidae and Libellulidae. Bulletin of American Odonatology 8(1):1-32.
Dunkle, S. 2000. Dragonflies through binoculars: a field guide to dragonflies of North America. Oxford University Press, New York, New York. 266 pp.
Legler, K., D. Legler, and D. Westover. 2013. Dragonflies of Wisconsin-Edition 5.1, copyright Karl Legler, self-published.
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.
Paulson, D. 2012. Dragonflies and damselflies of the east (Princeton field guides). Princeton University Press, Princeton, New Jersey. 544 pp.
Walker, E. M. 1958. The Odonata of Canada and Alaska : Anisoptera. Volume 2. University of Toronto Press, Toronta, Ontario, Canada. 330 pp.