Scientific Name: Gomphus quadricolor
Taxonomy Group: Arthropods
Last COSEWIC Assessment: April 2008
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Rapids Clubtail
The Rapids Clubtail is a small, dark-coloured dragonfly with a wing length of 25 to 27 mm. The eyes are widely separated, as in all Clubtails (in most other dragonfly families the eyes touch). The face is light green with two dark lines. The thorax has a contrasting colour pattern of brownish-black and yellowish-green stripes. The legs are black. The long, slender abdomen is black with linear yellow spots on the top and small lateral spots of the same colour. In the males, the tip of the abdomen is slightly expanded. The Rapids Clubtail can be confused with other members of the Clubtail family that share its habitat, but they all have a yellow dorsal stripe on the abdomen.
Distribution and Population
The Rapids Clubtail is found in Ontario and in 25 states in the northeastern and north-central United States. In Canada, it was historically known from four sites in southern and eastern Ontario: the Thames, Humber, Credit and Mississippi rivers. In 2005, the species was observed only at the Humber River and Mississippi River sites. The Canadian population is estimated at a minimum of 318 individuals, including 106 adults. Only adult males were observed during population surveys at the two extant sites; however, equal numbers of adult males and females and at least two nymphs (larvae) for every adult were assumed to be present at each site. The number of nymphs is thus a minimum estimate. There are no data on fluctuations or long-term trends in Rapids Clubtail populations.
The Rapids Clubtail typically inhabits medium to large streams and rivers with mostly wooded shorelines. The waters that it inhabits are typically clear and cool, with gravel and cobble riffles and projecting boulders interspersed with quiet, muddy pools. Alternating riffles and pools are probably very important for the species, since the females lay their eggs over the rapids and the eggs or newly hatched nymphs are then carried downstream to the pools. The nymphs live in these quiet, muddy pools. The adult males perch on rocks in the rapids. Shoreline rocks or vegetation may also be used, particularly where midstream boulders are absent. The adult females inhabit forests along the riverbanks, moving to the rapids when they are ready to mate. The decline of certain species of mayflies and other aquatic insects that are now limited to only a few short stretches of the Credit and Humber rivers is indicative of the habitat deterioration along these waterways.
Little information is available on the biology of this species. As in all dragonflies, the life cycle has an aquatic larval stage and a terrestrial adult stage. The adult stage lasts three to four weeks, while the larval stage probably lasts two or more years. In Ontario, the adult flight period falls between early June and early July. The adult males typically perch on rocks in midstream, making short forays over the riffles to forage, find mates and drive away competitors. Females inhabit the forest adjacent to the river, moving to the river only when they are ready to breed. Mating takes place above the water, and the female flies low over the rapids, depositing eggs on the surface of the water. Eggs and newly hatched nymphs are carried downstream to muddy pools. The nymphs spend most of their time buried in the muddy bottom of these pools, breathing through the tip of the abdomen raised above the sediments. Before the final moult, the nymphs crawl onto vegetation at the edge of the stream. Newly emerged adults disperse inland to avoid predation until their outer covering, or exoskeleton, has hardened and they are able to fly strongly. Adults are opportunistic predators, feeding on various small flying insects. Hidden in the sediments, the nymphs use a specialized mouth part, the prehensile labium, to ambush prey.
Habitat degradation is the most significant threat to the Rapids Clubtail. In Canada, three of the four sites are in the heavily developed part of southern Ontario, where continued urbanization threatens water quality in riparian habitats and natural terrestrial vegetation is declining. Loss of riparian forest could threaten adult Rapids Clubtails by exposing them to increased predation by birds and other dragonfly species. Females, which spend most of their lifespan in forest cover adjacent to the river, may be particularly vulnerable. Impoundment of running waters by dams is a potential threat in all known Canadian sites. In fact, all four rivers where the species has been recorded have numerous dams and other water control structures, and these rivers are actively regulated for flood control. Water quality in most southern Ontario streams has been degraded. High levels of chlorine, phosphorus and nitrates and possibly pesticides may threaten Rapids Clubtail nymphs. Finally, the introduction of exotic species is also a potential threat in these four rivers. The impacts of exotic species, if any, on the Rapids Clubtail are unknown, but the impacts could include predation, competition, increased turbidity and changes in the stream community structure. Collisions with cars could be a source of adult mortality where road crossings fragment the stream habitat, but the potential impact of vehicle-related mortality is unclear.
Federal ProtectionThe Rapids Clubtail is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
In Ontario, the species is not protected under any provincial statute. However, part of its habitat benefits from some degree of protection, since river habitat is protected by the fish habitat provisions of the federal Fisheries Act.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Rapids Clubtail (Gomphus quadricolor) in Canada
Status First posting on SAR registry
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
9 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
Recovery Document Posting Plans
- Date modified: