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Montana Field Guide

Montana Field Guides

Variable Darner - Aeshna interrupta


Global Rank: G5
State Rank: S5

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General Description
The Variable Darner is a member of the family Aeshnidae. Darners are among the largest and fastest-flying North American dragonflies, 2 1/4-4 3/4" (57-120 mm) long. Variable Darners are found state-wide from the mountains to the prairies. Preferred habitat includes a variety of lakes and ponds with dense shoreline vegetation, marshy or boggy ponds, fens, and saline ponds, as well as slow-moving streams (Nikula et al. 2002, Paulson 2009, Dunkle 2000). Associated Wetland ecological systems are numerous: Western Emergent Marsh, Northern Rocky Mountain Wooded Vernal Pool and the Rocky Mountain Subalpine-Montane Fen, Great Plains Open Freshwater Depressional Wetland, Great Plains Prairie Pothole,and potentially the Great Plains Saline Depression Wetland since these dragons can tolerate saline conditions.

Species Range
Montana Range

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Range Comments
A widespread and common darner found from Alaska south to Arizona east to Newfoundland, in Montana it has been found found throughout the western part of the state in a variety of lakes and wetlands.

Summary of Observations Submitted for Montana
Number of Observations: 248

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Variable Darners are found in many habitats, including a variety of lakes and ponds with dense shoreline vegetation, marshy or boggy ponds, fens, and saline ponds, as well as slow-moving streams (Dunkle 2000, Nikula et al. 2002, Paulson 2009). Away from breeding sites, Variable Darners can be found feeding, sometimes in very large swarms, in mountains clearings, open fields, and along roads. This species often perches vertically on tree trunks, branches, other available vegetation, and sometimes on rocks and the ground (Dunkle 2000, Nikula et al. 2002, Paulson 2009).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Larvae feed on a wide variety of aquatic insects, such as mosquito larvae, other aquatic fly larvae, mayfly larvae, and freshwater shrimp. They will also eat very small fish and tadpoles.
Adult- The dragonfly will eat almost any soft-bodied flying insect including mosquitoes, flies, small moths, mayflies, and flying ants or termites.

Reproductive Characteristics
Male Variable Darners patrol small territories and fly through vegetation often hovering and investigating for females. Copulating pairs, as well as tandem pairs, are seen for extended periods of time at breeding sites. Females oviposit on floating sedge and grass stems, upright herbaceous and shrub stems, as well as on wet logs (Dunkle 2000, Nikula et al. 2002, Paulson 2009).

References
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Citation for data on this website:
Variable Darner — Aeshna interrupta.  Montana Field Guide.  .  Retrieved on , from