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Ischnura damula (Plains Forktail)BC conservation rank: S1. Red List. For a long time known in BC only from Liard River Hot Springs, a rather fragile, though protected site. A second locality in the Kispiox Valley was recorded in 2002, but we have retained the S1 rank.Description: Male's coloration is like that of I. cervula; appendages, fig. 6b. Female's thorax is often similar to the males, or has pale spots on top joined into stripes; it may also be tan to pink. The abdomen's tip is blue. Females are less prone than I. cervula to darken with pruinescence; they have a vulvar spine. Length: male 28 mm, female 27 mm. Global Range: British Columbia and Yukon east to Manitoba, south to Texas and Arizona (Westfall and May 1996). Faunal element: Western (see Appendix 2). BC Distribution: In BC, found at Liard River Hot Springs on the Alaska Highway and at Elizabeth Lake in the Kispiox Valley. Biology: The isolated population at Liard River Hot Springs is probably a relic of a more widespread distribution during the warm climatic period (Hypsithermal) about 6000 years ago. The recently collected, first Yukon specimens are also from warm springs. In Alberta, one I. damula locality is warmed by a power plant, which mimics warm springs (Acorn 2004). Other sites are natural, non-spring habitats. At the second BC site in the Kispiox Valley specimens were not apparently associated with warm springs. Expected site associations are Wm01-02, Wm04, Wf01. Closely related to I. cervula and similar in appearance, but in BC, the ranges of the two species do not overlap. BC flight period: mid May to mid August; all records are from mid May to mid July. Management and protection considerations: Liard River Hot Springs is protected as a provincial park, although any plans to modify the water flows (any more than they already are) for bathing purposes should be carefully considered in light of the rare flora and fauna present. The site often gets significant tourist traffic but boardwalks on some trails protect the habitat somewhat from trampling. Better population estimates of the damselfly at the springs are required. The site at Elizabeth Lake is a Ministry of Forests recreational site and campground; it is mostly used by fishermen. The exact breeding place was not discovered, but this and the size of the population should be clarified. The habitat should be noted as vulnerable by the managers of the site. Further inventory in the Northeast and central BC plateaus, especially at warm springs, should be undertaken to expand our knowledge of the species distribution.
Ischnura damula Map 3. Frequency of records in British Columbia by NTS 1/50,000 mapsheet. |
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