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Montana Field Guide

Montana Field Guides

Zigzag Darner - Aeshna sitchensis

Potential Species of Concern

Global Rank: G5
State Rank: S2S3
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:


 

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State Rank Reason (see State Rank above)
The Zigzag Darner is currently ranked S2S3 as a "potential species of concern" in Montana because it is potentially at risk of extirpation in the state, due to limited and/or declining numbers, range and/or habitat, even though it may be abundant in some areas.
 
General Description
The Zigzag Darner is a relatively small, fairly uncommonly occurring member of the family Aeshnidae in Montana and a potential species of concern. Preferred habitat includes small bog pools with little to no emergent vegetation as well as fens and other shallow cold water pools with some moss cover and nearby wooded uplands. Many breeding sites chosen by this species dry up during the summer months (Dunkle 2000, Paulson 2009). The zigzag darner is distinctive with its zigzag thoracic stripes and a brown abdomen with pale blue spots.

Diagnostic Characteristics
The zigzg darner is distinctive with its zigzag thoracic stripes, small size and a brown abdomen with pale blue spots.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.
 


Range Comments
Zigzag Darners are widespread across Alaska; Labrador; Canada: Alberta, British Columbia, Manitoba, Newfoundland, North West Territories, Ontario, Quebec, Yukon; and the northern United States: from Maine/New Hampshire to Washington, south to Colorado, Wyoming and potentially extirpated in Utah(Needham and Westfall, 1955). In Montana, it has been collected from wet meadows in the Swan River Valley (Lake Co.), Skalkaho Pass (Granite Co.), and near Indian Meadows (Lewis and Clark Co.) (Miller and Gustafson 1996).

Summary of Observations Submitted for Montana
Number of Observations: 57

(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
Zigzag Darners prefer small bog pools with little to no emergent vegetation as well as fens and other shallow cold water pools with some moss cover and nearby wooded uplands. Many breeding sites chosen by this species dry up during the summer months (Dunkle 2000, Paulson 2009). Away from breeding sites this species can often be found perching on light-colored substrates located on the ground, on logs and trees in the nearby wooded uplands or in open clearings and logging roads. Although males mostly feed at breeding sites, both sexes also feed away from the water, but not late into the evening or swarms (Dunkle 2000 Paulson 2009). They have also been observed in wet meadows (Miller and Gustafson 1996).

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
Zigzag Darner males do not tend to hover, but do perch more often than other Darners, with short patrols over the open water and along the bog or fen edges without any apparent pattern. Females oviposit at the waterline in grasses or sedges or at any open water shoreline, often in moss beds, algal mats, or mud (Dunkle 2000, Paulson 2009).

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