Dragonflies

As part of the Living Landscapes Project in northern British Columbia (BC), the Royal British Columbia Museum (RBCM) and the Ministry of Environment's British Columbia Conservation Data Centre (CDC) joined forces, beginning in 2000, to study the dragonflies (Insecta: Odonata) of the region. The study area includes the province north of about 52º N, approximately the latitude of Williams Lake. Within this area, many wetlands such as streams, springs, marshes, peatlands, ponds and lakes were sampled. Once ecosystem classification is complete, some of these ecosystems might be considered threatened or endangered by the CDC. Sites east of the Rockies and along the Alaska Highway corridor east of Lower Post were sampled in 1997.

Northern BC was sampled in several stages. Figure 1 shows the annual survey areas. The first survey, which began in 2000, focused on the Upper Fraser Basin, centred on Prince George: field work covered the regions around the city and those far to the east and south, that is, the western slopes of the Rockies from Tête Jaune Cache north to Pine Pass, the northeastern Chilcotin Plateau (Nazko area) and the northern Cariboo Mountains (Likely, Quesnel Lake). Sporadic collecting also occurred along Highway 20 to the eastern boundary of Tweedsmuir Park. In 2001 the Vanderhoof-Omineca-Williston regions were examined; in 2002 it was the North Tweedsmuir-Babine-Bulkley-Skeena regions and, in 2003, the far Northwest, including the Hwy 37 corridor, Atlin area, Skagway and Haines roads were studied. No fieldwork was undertaken in 2004 in order to consolidate specimens, databases and other information. In 2005 some of the areas of the north coast around Prince Rupert, including the Skeena, Kitimat and Nass river valleys, were examined.

Figure 1. Dragonfly survey areas in British Columbia 1996-2006.

The project was a multi-year effort to determine the present status, precise location of occurrences and habitat requirements of the dragonflies of selected areas of northern BC. Although the RBCM had dragonfly specimens and a species list for the region that represented our knowledge up to 1999, with the exception of the Peace River drainage area, no comprehensive survey for dragonflies had ever been made; some of the recorded populations were known only from collections made in the mid-1900s.

The first dragonfly records from the northern parts of BC were published by Walker (1912, 1925, 1927), Buckell (1938) and Whitehouse (1941). Walker (1953, 1958), Walker and Corbet (1975), Scudder et al. (1976) and Cannings and Stuart (1977) updated and summarized the information known for BC. This latter book is out of print, but is available on the internet at RBCM. Since then, general collecting, mostly by RBCM, UBC and CDC staff, has improved our understanding of species distributions in BC and Yukon (Cannings 1980, 1996; Cannings et al. 1980, 1991; Cannings and Cannings 1987, 1994, 1997). The main sources of distributional information on the species of the region are the databases of the Spencer Entomological Museum at the University of BC in Vancouver and the Royal BC Museum in Victoria. These data have been used to produce distribution maps for all BC species, current to the end of 2004.

Despite the fact that aquatic invertebrates make up a key part of freshwater ecosystems, little is known of the distribution and ecology of most aquatic invertebrate groups, especially in the northern part of BC. This is true of even normally well-studied groups such as dragonflies (Cannings and Stuart 1977). Dragonflies are a priority group for inventory (Scudder 1996) because, unlike most invertebrates, they can be identified in the field and because field personnel experienced in dragonfly collecting are available.

Although development in northern BC has been concentrated for the most part in a few population centres, and the condition of most freshwater habitats (with some notable exceptions, such as those flooded by the WAC Bennett and Kenney dams) remains close to a pristine state, there is a need to establish baseline information regarding the distribution and habitat choice of aquatic invertebrates. The pace of development in the North is increasing and will undoubtedly continue to increase dramatically in the next century.

The dragonflies (including damselflies) comprise a relatively well-known order of insects that breeds in a wide variety of aquatic habitats. Some species are specialists using discrete habitats; others are generalists, able to survive in a wide variety of environments. In BC wetland habitats have been, and continue to be, altered, lost or destroyed because of urban development, agriculture and resource extraction (Stevens et al. 1995). Estimates indicate that 65 to 80% of wetlands have been altered or destroyed, depending on the region.

Dragonflies are upper-level predators in the invertebrate food-web, they can be linked to habitat quality and have often been identified as excellent indicators of ecosystem health (e.g., Carle 1979, Trevino 1997, Corbet 1999, Clarke and Samways 1996, Walker and Corbet 1975, Takamura et al.1991). Knowledge of the ecology of even common dragonflies is important; many aquatic ecosystems such as peatlands, marshes, and small lakes are not home to fish, and invertebrates are the dominant animals in them, yet at present we have no way to describe these communities or characterize their health. In these habitats, invertebrates such as dragonflies are the only animals convenient as indicators of ecosystem health. Many species are habitat-specific and their presence can be used to characterize healthy wetlands of all sorts. Within the constraints of weather, surveys are well-suited for long-term monitoring programs. Finally, because they are large, colourful, diurnal creatures with interesting behaviours, Odonata are excellent subjects for nature interpretation programs and public education about aquatic ecosystems in general.

The inventories in the North complement similar projects undertaken throughout much of southern British Columbia since 1996. Surveys in the Georgia Depression (1996), the Okanagan drainage (1997), the Peace River/Fort Nelson region (1997) and the Columbia/Kootenays (1998-99) (Fig.1) have resulted in many new discoveries, including the addition of five species to the provincial list (Cannings et al. 2005a, Kenner, 2000) and have consequently allowed us to make much more realistic conservation priorities for this group of insects (Cannings et al. 2000, Ramsay and Cannings 2000, 2005). The surveys can also be used as a baseline study in future aquatic ecosystem assessments. There are essentially no risks to populations, even of rare species, from this sort of limited collecting. Specimens in research collections have many values. For example, they serve as standards for species identification and unequivocally document historical status, distribution, and present geographical variation, including 'hidden', as yet undescribed, species. In addition, they contain life-history and ecological information such as the habitat choice of species and the time of adult emergence and breeding.

Despite the ecological importance of dragonflies, general public awareness and appreciation of them (and of other aquatic invertebrates, for that matter) is minimal. During the project, however, we have had much positive public feedback concerning dragonflies, largely because of the public talks given during the project and the publication of the Introduction to the Dragonflies (Cannings 2002a). In addition, dragonfly information posted on the RBCM's Living Landscapes Web page will be a popular addition to the material on these insects available on-line.

Although a provincial handbook on dragonflies existed (Cannings and Stuart 1977) before the start of the project, its species range maps revealed vast blank areas of ignorance north of Quesnel. A new book designed for the use of the general public and project volunteers was produced as part of the project (Cannings 2002a). It contains colour photos and simple identification information. Because the region is vast and so poorly known, it is impossible to complete an intensive inventory, even in six or seven seasons, thus, local volunteers were recruited and trained to build upon the foundation of the Living Landscapes survey.

The objectives of the study were

  • To determine the status, precise locations of occurrences, and habitat associations of the approximately 68 species of Odonata known or expected from northern BC, with a search emphasis on the 14 species considered to be potentially at risk (red- or blue-listed, as ranked by the Conservation Data Centre) at the outset of the survey in 2000.
  • To present a revised list of Odonata of BC, with conservation ranks assigned to species.
  • To develop management guidelines for each of the species considered at risk.
  • To provide baseline data that can be used for habitat monitoring and for the potential development of indicators of ecosystem health.
  • To improve the scope and utility of RBCM research collections.
  • To leave a legacy of awareness and knowledge of dragonflies in the region.
  • To foster an ongoing, local interest in dragonfly monitoring and research.

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