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| The Dragonflies
(Insecta: Odonata) of the Columbia Basin, British Columbia: Field Surveys, Collections Development and Public Education
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| Female ovipositing Aeshna tuberculifera. Photo: Blair Nikula. |
The project was a two-year effort to determine the present status, precise location of occurrences and habitat requirements of the dragonflies of selected areas of the Columbia Basin. Although the RBCM has dragonfly specimens and a species list for the region that represents our knowledge up to 1997, no comprehensive survey for dragonflies had ever been made: some of the recorded populations were known only from collections made in the early 1900s.
Dragonflies are invertebrates that seldom receive the attention they deserve from government biologists and resource managers. But they are of ecological importance for many reasons. They are upper-level predators in aquatic and semi-aquatic habitats, often dominating the large invertebrates, especially in fish-free systems. They inhabit, for the most part, the edges of water bodies, living in the riparian interface between land and water. Many species are habitat-specific and their presence can be used to characterize healthy wetlands of all sorts. Furthermore, unlike most invertebrates dragonflies are identifiable in the field by experts, and surveys can proceed with speed and efficiency. Within the constraints of weather, these surveys are well-suited for long-term monitoring programs. Finally, because they are large, colourful, diurnal creatures with interesting behaviours, dragonflies are excellent subjects for nature interpretation programs and public education about aquatic ecosystems in general.
Recently, similar inventories have been carried out by the CDC and the RBCM in southwestern British Columbia, the Okanagan Valley and the Peace River region, which have resulted in many new discoveries that have greatly increased our knowledge of dragonfly distribution and ecology. This new information improves our ability to produce comprehensive public programs such as Web pages, interpretive programs and publications (such as the planned fieldguide to the dragonflies of Northwestern North America), which will be useful and informative to students, naturalists and professional biologists in the Columbia Basin and further afield. Detailed inventory information will help local and provincial habitat managers and National Parks staff to make better informed decisions about wetland environments, and to set realistic conservation priorities for wetlands.
The three main objectives of this project were:
We surveyed dragonflies in selected areas throughout the Basin over the 1998 and 1999 field seasons. Experienced RBCM and CDC staff were the primary field workers doing collection, identification, data entry and photography. In addition, several Basin residents who expressed interest in the study helped gather specimens and data. (Appendix 3 lists the participants.) Students in the Co-operative Programs of the University of Victoria and Simon Fraser University helped create the initial databases and distribution maps.
In 1998 the survey focused on the mountain ranges and the Rocky Mountain Trench north of Invermere, especially in the four National Parks there (Kootenay, Yoho, Glacier and Mount Revelstoke). Many of the rare species of management concern are found in the northern mountainous areas of the region. The project met the interpretive and management goals of Parks Canada, and it agreed to support the project. In 1999 we concentrated on the southern Trench and in the Creston-Kootenay Lake region and selected areas to the west, especially along the Highway #3 corridor. Due to the size of the study area, and time and financial constraints, we did not cover the whole region.
We visited the widest possible array of habitats to identify and note adult dragonflies. We usually netted specimens for close examination and kept voucher specimens. Larval specimens or the cast skins of larvae (exuviae) can also be used as indicators of a species' use of a particular site. Both adult and larval specimens were prepared, labelled, identified and accessioned into the RBCM collections.
Details of numbers of dragonflies, their behaviour and ecology, as well as precise UTM grid coordinates were recorded and entered into an RBCM database. Distribution maps of each species were produced using ArcView GIS. The distribution of larvae and breeding adults was analysed to determine critical habitats.
Slide shows of two types (slides on videotape with voice-over commentary; shows made up of individual slides and associated hardcopy text) were distributed to parks and naturalist organizations for use in interpretive programs.
The English names of dragonflies used in this report are those adopted by the Dragonfly Society of the Americas (Paulson and Dunkle 1996). Except for the Introduction, these names are not used in the body of the report, but are listed in Appendix 1.
The first dragonfly records from the Kootenays were listed by Currie (1905). Other early major works by Walker (1912, 1925, 1927), Buckell (1938) and Whitehouse (1941) also included references to the Columbia Basin dragonflies. Walker (1953, 1958) and Walker and Corbet (1975), cited some of the earlier works mentioned above while researching the dragonflies of Canada and Alaska. Scudder et al. (1976) and Cannings and Stuart (1977) updated and summarized the information known for British Columbia. Since then, general collecting, mostly by RBCM and CDC staff, has improved our understanding of regional species distributions in minor ways (Cannings 1980a, Cannings 1983, Cannings and Cannings 1983, Cannings 1984, Cannings and Cannings 1994). The main sources of distributional information on the species of the region are the databases of the Spencer Entomological Museum, at the University of B.C. in Vancouver, and the Royal B.C. Museum in Victoria.
Overview of the Project Continued . . .
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