Dragonflies: Pacific clubtail
(Odonata: Anisoptera: Gomphidae) Profile prepared by Sarah Foltz, The Xerces Society for Invertebrate Conservation
Gomphus kurilis is a western North American species whose distribution extends from the Seattle area of Washington, south through Oregon, to the northern half of California. It occupies a wide range of aquatic habitat, including sand-bottomed lakes, muddy ponds, large, swift rivers, and slow streams. The larvae of this species require fine substrate for normal burrowing behavior. Road construction, building construction, cattle grazing, and logging-related activities in the watershed degrade aquatic substrate through increased erosion and sediment delivery, and pose threats to this species. Additionally, insecticides, herbicides, and other contaminants carried in agricultural run-off and wind drift may have serious consequences for the reproductive potential and long-term survival of this species.
Adult: A medium-sized (45-50 mm; 1.8-2 in.) dragonfly in the family Gomphidae. Adults in this family are characterized by having separated eyes and the last segments of the abdomen usually enlarged. This species has a green face, blue eyes, black legs, and black abdomen with yellow on the dorsal (top) surface of each segment, and large, yellow spots on the underside of abdominal segments 8 and 9 (Gordon and Kerst 2005). The presence of conspicuous pale markings on the sides of the thorax that are wider than the dark stripes in between is diagnostic of this species. Also, the dark stripe under the hindwing base is much narrower than the dark stripe at the base of the forewing (Paulson 2007a).
Immature: Gomphus larvae can be identified as follows: prementum and palpal lobes flat (as opposed to cup-shaped), wing pads parallel, antennae with 4 segments, the third of which is cylindrical and elongate (as opposed to flat and short), abdominal segment 8 with anterolateral sclerites, and sternum of last abdominal segment usually wider than long (Tennessen 2007). Species identification is difficult for a non-expert.
Range-wide: Records are on the west side of the Cascades from the Seattle area of Washington, south through western Oregon and through the northern half of California. More common in Oregon and California than in Washington.
Washington: Two populations are known: east side of Black Lake, Thurston Co., and south side of Ice House Lake, Skamania Co., although confirmation of this species’ current status at these sites is needed (Paulson 2008, pers. comm.). There are historical records (one from 1933, one undated) from Lake Washington in the Seattle area, King Co. (Paulson 2007b), but sporadic surveys of Lake Washington in recent years have not found this species (Paulson 2008, pers. comm.).
Oregon: Relatively common in central and southern Oregon (Paulson 2008, pers. comm.), occurring north to the central Willamette Valley (Johnson and Valley 2005) at sites from sea-level to 1463 m (4800 ft). Particularly abundant at streams in the Western Interior Valleys (between the Cascade Range and the coast), and also has a stronghold at the Klamath Basin in the Eastern Cascades (Johnson and Valley 2005). There are no records in northern Oregon, a few records in Linn Co. (Gordon and Kerst 2005), and this species is relatively common south of Benton, Linn, and Deschutes Counties. It is fairly common in the southern Willamette Valley in Lane County, and has been seen near the mainstem Willamette River in Alton Baker Park (in Eugene) and the Coast Fork at Mt. Pisgah (southeast of Eugene). It has also been found in ponds within one mile of the Willamette River (Gordon and Kerst 2005).
Abundance estimates of this species are not known.
In Washington, this species is found at lentic sites, including ponds, lakes, and slow streams. The habitat range in Oregon is wider, including sand-bottomed lakes, rock-bottomed lakes, muddy ponds, large, swift rivers, slow, eutrophic rivers, slow streams. This species can apparently tolerate some agricultural pollution (Johnson and Valley 2005). Larvae burrow in mud or sand and ambush prey. Adults bask on the ground near water and on vegetation or on the ground if away from water (Valley 2005). Population sites in Washington are below 50 meters (164 ft.) elevation, with the exception of the King Co. record, which was at 610 m (2000 ft.). Sites in Oregon range up to 1463 m (4800 ft.).
Although Oregon supports a fairly large number of population sites for this species, there are few and possibly declining numbers of sites in Washington, and it is unclear if population sizes in either state are also declining.
Habitat disturbance and degradation are the main threats to this species. The larvae of this species require fine substrate for normal burrowing behavior. Road construction, building construction, and logging-related activities in the watershed degrade aquatic substrate through increased erosion and sediment delivery (Rothrock et al. 1998). The loss of trees through timber harvest poses additional threats, since trees provide (1) shade that maintains lower water temperatures for larvae and (2) foraging and nighttime roosting areas for adults (Packauskas 2005).
Locally, watershed cattle grazing and agricultural pollution pose additional threats to this species. Grazing by livestock not only reduces the amount of vegetation available for perching and emerging, but also has deleterious impacts on water quality, including increases in nutrient levels due to introduction of livestock waste material into waters, and increases in temperature, sediment, and turbidity due to trampling and bank alteration (Agouridis et al. 2005, Mazzacano and Black 2008). Although this species has been found in agriculturally polluted habitat, insecticides, herbicides, and other contaminants carried in agricultural run-off and wind drift may have serious consequences for the reproductive potential and long-term survival of this species. Organic pollution and toxic chemicals have been recognized as a threat to members of this family (Paulson 2008, pers. comm.).
Global climate change may further threaten the long-term survival of this species. Projected changes in this region include increased frequency and severity of seasonal flooding and droughts, reduced snowpack to feed river flow, increased siltation, and increased air and water temperatures (Field et al. 2007), all of which could impact this species’ habitat unfavorably. Moreover, since many aspects of odonate survival (e.g. development, phenology, immune function, pigmentation, and behavior) are sensitive to changes in temperature, global climate change is predicted to have serious consequences on this taxon (Hassall and Thompson 2008).
It is not known if disease and predation are serious threats to this species, but stocking of non-native fish species for commercial or recreational purposes could negatively impact population survival, since the larvae may not be adapted to co-exist with such predators.
Inventory: This species is known widely throughout western Oregon and probably does not require further immediate sampling in the state (Paulson 2008, pers. comm.). It is rare in Washington, being known from only a few slow-water breeding sites. The broader habitat use in Oregon, including large, swift rivers and streams, suggests that the species may have a wider distribution in Washington than is currently documented. Additional survey work, particularly at the varied aquatic habitats around and between the existing Washington sites, may reveal more Washington populations. Future surveys should also focus on establishing the status of this species at known and historic Washington sites. The last known record of this species in Lake Washington (Seattle area) was in 1933. Dr. Paulson has looked unsuccessfully for this species in Lake Washington, but considering the very large size of the lake and the brief flight season of this species, its presence could have easily gone unnoticed (Paulson 2008, pers. comm.). The last record of this species from Black Lake (Thurston Co.) was in 2000, and the site has not been surveyed since. Ice House Lake (Skamania Co.) appears to have a current population of this species, although its stability at the site is unknown. The species wasn’t encountered when the site was revisited in the summer of 2003 (Paulson 2008, pers. comm.), but one individual was documented in 2007 (Johnson 2008, pers. comm.). Re-evaluation of this species’ status at each of these sites is critical to identifying both its current distribution and its conservation needs. Abundance estimates for this species at new and recorded sites would also assist future conservation efforts, since population size is important in evaluating the stability of a species at a given locality.
Management: All known sites and their associated watersheds should be protected from practices that would adversely affect any aspect of the odonate life-cycle. Since the largest proportion of an odonate’s life is spent as an aquatic larva, protecting the larval stage is most critical for the species’ success (Packauskas 2005). Water quality and water levels should be maintained at known sites and in other potential habitat in Washington. Fish management should focus on retention of the native species with which the insect community is adapted to co-exist; stocking of non-native species should be avoided or minimized. Adaptive land management practices, such as conserving and restoring riparian buffers around known aquatic habitats and fencing to exclude livestock, may help protect this species from the impacts of grazing and agriculture (Packauskas 2005).
Abbott, J.C. 2007. “Gomphus kurilis records.” OdonataCentral: An online resource for the distribution and identification of Odonata. Texas Natural Science Center, The University of Texas at Austin 3 Oct. 2008 < http://www.odonatacentral.org.>.
Agouridis, C.T., Workman, S.R., Warner, R.C., and Jennings, G.D. 2005. Livestock grazing management impacts on stream water quality: a review. Journal of the American Water Resources Association. 41 (3): 591-606.
Field, C.B., Mortsch, L.D., Brklacich, M., Forbes, D.L., Kovacs, P., Patz, J.A., Running, S.W. and Scott, M.J. 2007. Chapter 14: North America. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Parry, M.L., Canziani, O.F., Palutikof, J.P., van der Linden, P.J. and Hanson, C.E., eds.). Cambridge University Press, Cambridge, UK. Available at: www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter14.pdf
Gordon, S. and C. Kerst. 2005. Dragonflies & Damselflies of the Willamette Valley, Oregon: A Beginners Guide. CraneDance Publications, Eugene, OR. 110pp.
Hassall, C. and D.J. Thompson. 2008. The effects of environmental warming on Odonata: a review. International Journal of Odonatology 11(2): 131-153.
Johnson, J. and S. Valley. 2005. The Odonata of Oregon. Bulletin of American Odonatology 8(4): 101-122.
Johnson, J. 2008. Personal communication with Sarah Foltz.
NatureServe. 2008. “Gomphus kurilis.” NatureServe Explorer: An online encyclopedia of life [web application]. Feb. 2008. Version 7.0. NatureServe, Arlington, Virginia. 6 Oct. 2008 <http://www.natureserve.org/explorer/>.
Mazzacano, C. and S.H. Black. 2008. Petition to emergency list Susan’s Purse-making Caddisfly (Ochrotrichia susanae) as an endangered species under the U.S. Endangered Species Act. 8 July 2008. Xerces Society for Invertebrate Conservation. 28 Oct. 2008. <http://www.xerces.org/Endangered/Xerces_Society_Susan%27s_caddisfly_petition_July_8_2008.pdf>
Paulson, D. 2007a. “Washington Odonata.” Slater Museum of Natural History. Oct. 2007. University of Pugut Sound. 6 Oct. 2008 <http://www.ups.edu/x7041.xml>. Paulson, D. 2007b. “Field Key to Adult Washington Dragonflies (Odonata).” Slater Museum of Natural History. Jan. 2007. University of Pugut Sound. 2 Oct. 2008 <http://www.ups.edu/x6518.xml>.
Paulson, D. 2008. Personal communication: E-mail exchange with Sarah Foltz regarding Pacific Northwest odonates.
Rothrock, J. A., Barten P. K., and Ingman, G. L. 1998. Land use and aquatic biointegrity in the Blackfoot River watershed, Montana. Journal of the American Water Resources Association 34 (3): 565-581.
Tennessen, K. 2007. Odonata Larvae of the Pacific Northwest: An Identification Manual. Created for use in a taxonomic workshop sponsored by the Xerces Society and held at Evergreen State College, Olympia, Washington, March 16-18, 2007.
Valley, S. 2005. E-mail exchange with John Fleckenstein regarding odonates.