BC Conservation Data Centre: Conservation Status Report
Stylurus olivaceus
Olive Clubtail
| Scientific Name: | Stylurus olivaceus |
|---|---|
| English Name: | Olive Clubtail |
| Provincial Status Summary | |
| Status: | S3S4 |
| Date Status Assigned: | March 15, 2023 |
| Date Last Reviewed: | March 15, 2023 |
| Reasons: | This species is found from the Thompson River valley, south through the Okanagan Valley and east to Christina Creek and Kootenay Lake near Nelson. Threats are considered low and trends remain unkown. It was designated "Endangered" by COSEWIC in 2011, however since this time there have been new locations found, including one in a new area. |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Comments: |
The estimated range extent is just over 22,000 km2. It is found from the Thompson River valley in the north, south through the Okanagan Valley and east to Christina Creek and Kootenay Lake near Nelson. When this species was last assessed the range extent was estimated to be 10,936 sq. km (COSEWIC 2011b). The increase in range extent is due to a new (2022) record at Lake Kootenay and to a record from 2021 10 km east of Kamloops. |
| Area of Occupancy (km2): | F = 126-500 |
| Area of Occupancy Estimate (km2): | 200 |
| Area of Occupancy Comments: | The Index of Area Occupancy using a 2 km x 2 km grid is approximately 200 km2. It was 184 sq. km (COSEWIC 2011b) for the previous assessment. |
| Occurrences & Population | |
| Number of Occurrences: | B = 6 - 20 |
| Comments: | There are eight known element occurrences in B.C.; they occur in four distinct regions - Christina Creek, the Okanagan Drainage (especially parts of the Okanagan River from Penticton), South Thompson River, between just west of Kamloops and Pritchard (COSEWIC 2011b, iNaturalist; accessed February 2023). There may be a few more found, but unlikely more than 20. |
| Number of Occurrences with Good Viability / Ecological Integrity: | BC = 1 - 12 |
| Number of Occurrences Appropriately Protected & Managed: | B = 1 - 3 |
| Comments: | The most important riverine protected areas in the Thompson-Okanagan (from south to north) are: South Okanagan Wildlife Management Area (British Columbia Ministry of Environment), Vaseux-Bighorn National Wildlife Area (Canadian Wildlife Service), Okanagan Falls Prov. Park, Pritchard Prov. Park and Banana Island Prov. Park; the last two are on the Southern Thompson River. Other protected areas, all associated with lakeshores, include Haynes Point Prov. Park, Vaseux Lake Prov. Park, Okanagan Mountain Prov. Park, Sunoka Prov. Park, Okanagan Lake Prov. Park, Bear Creek Prov. Park, Fintry Prov. Park, Ellison Lake Prov. Park, Kalamalka Lake Prov. Park, and Shuswap Lake Prov. Park. At Christina Lake, Christina Lake Nature Park (managed locally), and possibly Christina Lake Gladstone Prov. Parks might be of minor importance (COSEWIC 2011b). |
| Population Size: | U = Unknown |
| Comments: |
Population for British Columbia in 2011 was estimated at 2,500-90,000 individuals: Christina Creek - < 500; Okanagan Valley - 1,000-50,000; South Thompson River - 1,000-40,000. However the large ranges in these estimates render them unsatisfactory. These are rough estimates based on limited survey data and include a number of assumptions (COSEWIC 2011b). Population is generally not used for Conservation Status assessments for invertebrates because of the high variability in the numbers and the difficulty in determining populations. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | D = Low |
| Comments: |
The following threats are taken from the 2011 COSEWIC report (COSEWIC 2011b): The primary threat to the Stylurus olivaceus is the current and historical alteration, degradation, and loss of the limited natural shorelines and littoral zones of lakes and rivers that support diverse invertebrate communities in the low valleys of the Thompson-Okanagan region. This is an area of rapid human population growth and increasing land development. Dredging and channeling of the Okanagan River in the 1950's has altered much of the species habitat, and the effects of this single event, half a century ago, are unknown. Dredging and channeling reduce habitat heterogeneity, and alter river hydrology. This usually results in increased water velocities that lead to scouring and erosion, presumably reducing the availability of fine burrowing materials. The creation of dykes lining channels decrease streamside vegetation, resulting in increased water temperatures in some sections of the river, which may reduce larval viability in Stylurus olivaceus. However, Stylurus olivaceus still persists along dyked portions of the Okanagan River. The introduction of exotic species has altered the fish populations in the Okanagan River and associated lakes, and fish are a major predator of odonate larvae. As well invasive aquatic plants such as Milfoil (Myriophyllum spicatum) have been increasing annually in Christina Creek and at the outlet of Christina Lake, and it's effect on habitat suitability for Stylurus olivaceus is unknown. Pollutants pose a threat to Stylurus olivaceus from several sources including land development, agricultural practices, storm water runoff, sewage systems, forestry and range activities, atmospheric deposition and boating and marine activities. No specific information is available on the effects of pesticides on the Stylurus olivaceus which is a potential problem in the Southern Okanagan because the Okanagan River flows through many orchards and vineyard lands. Areas where roads and railways are adjacent to rivers pose several threats from spills of toxic chemicals, vehicle pollutants, and road-kill. Roads follow both banks of most of the Thompson River known to support Stylurus olivaceus and two-thirds of the 6 km of river in Penticton is bordered by a highway. As well several bridges cross all three of the streams known to produce this species in Canada. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | There is no information on the population trends of the Olive Clubtail in British Columbia. |
| Long-Term Trend: | U = Unknown |
| Comments: | There is no information on the population trends of the Olive Clubtail in British Columbia. |
| Other Factors | |
| Intrinsic Vulnerability: | BC=Moderately vulnerable to not intrinsically vulnerable. |
| Comments: | There is some vulnerability associated with requiring a waterbody for a large portion of a life. This is the only representative of the genus Stylurus in the province. |
| Environmental Specificity: | B=Narrow. Specialist or community with key requirements common. |
| Comments: | Habitat is warm, mesotrophic lowland rivers (a scarce habitat in B.C), and occasionally along sandy lakeshores. There are few odonates that develop in streams in BC; this species may be a good indicator of stream ecosystem health. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Ramsay, L (2023) and R. Cannings |
| Date: | December 23, 2022 |
| References | |
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GBIF.org. 2023. GBIF Occurrence Download for Stylurus olivaceus BC observations: https://doi.org/10.15468/dl.anbdv4 |
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COSEWIC 2011b. COSEWIC Assessment and Status Report on the Olive Clubtail, Stylurus olivaceus. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 58pp.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2022. Conservation Status Report: Stylurus olivaceus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 6, 2026).