Laura’s clubtail evaluation

Photo by Linda Gilbert

Assessed June 2010 by COSSARO as Endangered

Part 1: COSSARO candidate species at risk evaluation form – June 2010

Laura’s Clubtail (Stylurus laurae)

Current designations:

GRANK – G4 (January 1999)
NRANK Canada – N1
COSEWIC -- Endangered (April 2010)
SARA – Not Listed
General Status Canada – May be at Risk
ESA 2007 – Not listed
SRANK – S1
General Status Ontario – May be at Risk

Distribution and status outside Ontario:

Range includes Ontario and 17 states in the US extending from the Florida Panhandle to east Texas, north to Michigan and southern Ontario. Most common in the south central US east of the Appalachians.

Eligibility criteria

Native status

Yes. Recently discovered in Ontario, but not known to be invasive and almost certainly native.

Taxonomic distinctness

Yes. First described in 1932 and universally recognized as a full species.

Designatable units. The two streams constituting the Ontario range are within 23 km of each other and represent a single designatable unit.

Priority-setting criteria

Recent Arrival

No. Discovered in Ontario in 1999, but probably present for > 25 years.

Non-resident

No.

Primary criteria (rarity and declines)

1. Global rank

   Not in any category. G4.

2. Global decline

   Not in any category. Global population is stable (unchanged or within +/- 10% fluctuation in population, range, area occupied, and/or number or condition of occurrences) (NatureServe 2010).

3. Northeastern North America ranks

   Endangered. Occurs as a native species in 7 of 29 northeastern jurisdictions. Srank or equivalent information available for 7 of 7 jurisdictions = (100%). S1, S2, SH, or SX in 7 of 7 = (100%).

4. Northeastern North America decline

   Not in any category. Probably similar to global population: stable (unchanged or within +/- 10% fluctuation in population, range, area occupied, and/or number or condition of occurrences) (NatureServe 2010).

5. Ontario occurrences

   Endangered. Four occurrences (NHIC 2010) and two "locations" (COSEWIC 2010) on Big Creek and Big Otter Creek.

6. Ontario decline

   Insufficient Information. Ontario population is recently discovered and no numerical estimates prior to 2008 or long term population trend data are available.

7. Ontario’s conservation responsibility

   Not in any category. Ontario has far less than 10% of the global range (global extent of occurrence = 1.5 million km². Ontario extent of occurrence = 256 km²).

Secondary criteria (threats and vulnerability)

1. Population sustainability

   Insufficient Information. No Population Viability Analyses have been conducted for the species in Ontario or elsewhere.

2. Lack of regulatory protection for exploited wild populations

   Not in any category. May be occasional taken by collectors, but unlikely to threaten populations. Proposed Endangered federally by COSEWIC in April 2010.

3. Direct threats

   Threatened. Aquatic habitat degradation through pollution, water removal for irrigation, and invasive species (especially Round Goby) are threats to all Ontario occurrences. Nitrate and phosphorus concentrations in both watersheds consistently exceed water quality objectives. Water removal for irrigation significantly reduces stream flow during dry summers. Round Goby has invaded the streams since about 2004 and is potentially a significant predator on larvae.

4. Specialized life history or habitat-use characteristics

   Threatened. Larvae inhabit small to medium unpolluted sandy streams in the Carolinian Zone in southern Ontario. This habitat is restricted to a few streams in the Norfolk Sand Plain.

COSSARO criteria met (primary/secondary)

• Endangered – [2/0]
• Threatened – [0/2]
• Special concern – [0/0]

Recommended status: Endangered

Summary

Laura’s Clubtail is a medium sized dragonfly inhabiting clean, sandy streams in eastern North America from Ontario, south to Florida and Texas. Its Ontario range includes sections of Big Creek and Big Otter Creek on the north shore of Lake Erie. The larvae burrow in the silt and sand in the stream bed for two years or more. The adults emerge in July or early August and disperse to the surrounding forest until they return to the stream to breed. Laura’s Clubtail was discovered in Ontario in 1999 and population trends are unknown. Threats include aquatic habitat degradation through pollution, water removal for irrigation, and the invasive Round Goby. Given its small population size, limited distribution, and declines in habitat quality, this species is classified as Endangered in Ontario.

Information sources

COSEWIC. 2010. COSEWIC 2-month interim updated status report on Laura’s Clubtail (Stylurus laurae) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, Ontario. iv + 33 p.

Howell, D., Iowa Natural Areas Inventory, Department of Natural Resources. pers comm. 2009. Email correspondence to A. Harris. January 2009. Natural Heritage (NHIC) 2010. Website. Accessed May 2010

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available. (Accessed: May 28, 2010).

Appendix 1: Northeastern North America rank, status and decline

Occurs as a native species in 7 of 29 northeastern jurisdictions SRANK or equivalent information available for 7 of 7 jurisdictions = (100%) S1, S2, SH, or SX in 7 of 7 = (100%)

Part 2: Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

N/A. There are no accurate population data

Criterion B – small distribution and decline or fluctuation

Endangered. B1ab(iii)+2ab(iii) The maximum area of occupancy encompasses 22 km² (using a 1 km x 1 km grid) or 60 km² (using a 2 km x 2 km grid) and extent of occurrence is 256 km². Less than 5 locations, and there is observed, inferred and projected decline of habitat.

Criterion C – small population size and decline

N/A. There are no accurate population data

Criterion D – very small or restricted

Threatened. D2. Meets Threatened D2 as there are less than 5 locations and the populations are subject to rapid loss due to pollution or water withdrawal.

Criterion E – quantitative analysis

N/A. Not undertaken.

Rescue effect

No. Unlikely since the nearest population is 120 km across Lake Erie and there is little suitable intervening habitat. Adults are non-migratory.