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Montana Field Guide

Montana Field Guides

Twelve-spotted Skimmer - Libellula pulchella


Global Rank: G5
State Rank: S5
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:


 

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State Rank Reason (see State Rank above)
This species is widespread and abundant throughout the state.
  • Details on Status Ranking and Review
    Twelve-spotted Skimmer (Libellula pulchella) Conservation Status Review
    Review Date = 09/18/2008
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    ScoreF - 20,000-200,000 km squared (about 8,000-80,000 square miles)

    Comment20,000-200,000 km2 (125,000-500,000 acres)

    Area of Occupancy

    ScoreF - 500-2,000 km squared (about 125,000-500,000 acres)

    Comment500-2000 km2 (125,000-500,000 acres)

    Long-term Trend

    ScoreF - Increase (increase of >25%)

    CommentStock Pond creation in the prairies has increased the habitat for this species

    Short-term Trend

    ScoreE - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation

    CommentDocumenting many additional populations since 2006

    Threats

    ScoreG - Slightly threatened. Threats, while recognizable, are of low severity, or affecting only a small portion of the population or area.

    CommentWetland loss, Climate Change, Drought

    SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.

    ScopeLow - 5-20% of total population or area affected

    CommentNo threats identified

    ImmediacyLow - Threat is likely to be operational within 5-20 years.

    CommentNo threats identified

    Intrinsic Vulnerability

    ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).

    Environmental Specificity

    ScoreD - Broad. Generalist. Broad-scale or diverse (general) habitat(s) or abiotic and/or biotic factors are used or required by the species, with all key requirements common in the generalized range of the species in the area of interest. If the preferred food(s) or breeding/nonbreeding microhabitat(s) become unavailable, the species switches to an alternative with no resulting decline in numbers of individuals or number of breeding attempts.

 
General Description
The 12 spotted skimmer is a large showy dragonfly in the skimmer family; it looks even larger when flittering around the wetland because of the numerous spots placed along the length of the wing (6 spots on each side with black at the tip, a white spot nearest the tip is the Eight-spotted Skimmer). In mid-summer (July & August), they are very active and territorial often covering the whole wetland or lake shore on patrol and then returning back to the same area. This species is found statewide in ponds, lakes and wetlands with abundant emergent vegetation and oftentimes some open water. Like all adult dragonflies they eat smaller flying insects such as mosquitoes and flies, but will also take down damselflies and moths.

Phenology
Adults are most active in mid-summer, July & August, but can persist into September.

Diagnostic Characteristics
The 12 spotted skimmer has numerous spots alternating white and black along the length of the wing (6 spots on each side with black at the tip, 4 spots per wing and a white spot nearest the tip is the Eight-spotted Skimmer).

Species Range
Montana Range

Click the legend blocks above to view individual ranges.
 


Summary of Observations Submitted for Montana
Number of Observations: 271

(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)



Migration
Although there is no evidence of Twelve-spotted Skimmers migrating to or from Montana, some individuals do indeed migrate along the Atlantic coast (Dunkle 2000, Nikula et al. 2002).

Habitat
Twelve-spotted Skimmers prefer habitats of lakes and ponds, often shallow or semipermanent, as well as slow streams, marshes, and bogs. They are also commonly encountered in open fields where they forage (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 Twelve-spotted Skimmers are more territorial than Eight-spotted Skimmers with lengthy flights back and forth along shoreline and open water areas, but these territories change daily. Males are very aggressive towards other males and territorial disputes are common, involving repeated vertical loops and the male who succeeds in circling his competition is considered the winner. Copulation is quick and completed in flight. Females oviposit by splashing eggs into dense emergent vegetation or floating logs with male guarding nearby, although this guarding is only effective at low population densities (Nikula et al. 2002, Paulson 2009).

References
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Citation for data on this website:
Twelve-spotted Skimmer — Libellula pulchella.  Montana Field Guide.  .  Retrieved on , from