Rapids clubtail (Gomphus quadricolor) COSEWIC assessment and status report: chapter 12
Technical Summary
Gomphus quadricolor
Rapids Clubtail – Gomphe des rapides
Range of Occurrence in Canada:
Ontario
Extent and Area Information
Extent of occurrence (EO) (km²)
Narrow strip 8.25 km (Pakenham to Blakeney) by 314 km (Pakenham to Kleinburg) by 3 km (distance on Humber), thus about 1570 km². See Canadian Range. 1570 km²
Specify trend in EO.
Declining (extirpated at two historical locations based on surveys over the past decade)
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
The maximum area of occupancy encompasses an 800 m zone on either side of the stream length occupied by the species (800 m is the approximate maximum known dispersal distance inland for Gomphus quadricolor) See Canadian Range. 26 km² (maximum) or using the 1×1 km grid system 4 km² currently and 6 km² historically
Specify trend in AO :
Declining (extirpated at two historical locations based on surveys over the past decade)
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations:
Two
Specify trend in # :
50% decline
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat :
Quality of habitat apparently declining (See Habitat Trends)
Population Information
Generation time (average age of parents in the population):
Unknown; probably 2 years or more
Number of mature individuals :
Minimum of 106 estimated in 2005, maximum number is unknown
Total population trend:
Declining (extirpated at two historical locations)
% decline over the last/next 10 years or 3 generations.
Unknown
Are there extreme fluctuations in number of mature individuals?
Unknown
Is the total population severely fragmented?
Yes
Specify trend in number of populations:
Decling
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
- Mississippi River: 50
- Humber River: 56
Threats (actual or imminent threats to populations or habitats)
- Water pollution
- Water level regulation
- Invasive aquatic species
- Loss of forest cover in watershed
- Collisions with vehicles
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Stable nationally, although declining in some states, especially in south and east
Is immigration known or possible?
Possible but unlikely
Would immigrants be adapted to survive in Canada?
Possibly
Is there sufficient habitat for immigrants in Canada?
Possibly
Is rescue from outside populations likely?
No (See Rescue Effect)
Quantitative Analysis
Not applicable
Current Status
- COSEWIC: Endangered, April 2008.
- Global: G3G4
- Canada: N1
- US: N3N4
- S1: ON, CT, GA, IA, ME, MD, MA, VI
- S2: IN, NJ
- S1S2: NC, NY, PA
- S2S3: KY, WV, MI
- S3S4: AL, TN
- S4 : WI
- SNR: AR, IL, MN, MO, NH, OH, VT
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B1ab(iii)+2ab(iii)
Reasons for Designation: This distinctive species of dragonfly has a fragmented distribution with a very small extent of occurrence and area of occupancy, and is currently only found in small portions of two southern Ontario rivers. The species is believed to be extirpated at two historic sites and there is evidence for continuing decline of habitat.
Applicability of Criteria
Criterion A (Declining Total Population): Population information inadequate.
Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab(iii)+2ab(iii) since the known extent of occurrence (1570 km²) is less than 5000 km² and the area of occupancy (26 km²) is less than 500 km². Also, the habitat, area, extent and number of locations have declined over the last several decades.
Criterion C (Small Total Population Size and Decline): Population information is not adequate.
Criterion D (Very Small Population or Restricted Distribution): Population information is inadequate but comes close to meeting criteria D2 since the population is suspected to be small with a minimum estimate of 106.
Criterion E (Quantitative Analysis): Not applicable.
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