A. sitchensis is a small species with the lateral thoracic stripes narrow and so strongly notched and extended that they form a characteristic zigzag shape. The first (most anterior) stripe, in particular, has a distinct zigzag pattern. The two stripes are often broken and may have a spot or streak between them, and the frontal stripes are reduced or lacking. The “t-spot” on the top of the head is unique in having the two ends of the base convex upward toward the crossbar. The face is generally pale yellow with a distinct black cross-line. Males of this species have brown eyes mixed with blue around the edges, and all of the pale markings on the body are light blue with no green or yellow. Females of this species are polymorphic; the andromorph (resembling the male) has blue eyes and blue pale markings on the body, while the heteromorph (appearing different than the male) has brown eyes with blue highlights, yellow thoracic stripes, and yellow to white spots on the abdomen. No other Aeshna species whose ranges overlap with this species in Washington or Oregon are as small and blue, nor do they have the characteristic zigzag lateral thoracic stripes.
This species occurs in wet sedge meadows, fens, bogs, and very shallow peaty ponds. Moss appears to be an important oviposition substrate at bogs and fens, with floating mats and mossy edges and bottoms of small, shallow pools or spring channels providing appropriate egg-laying habitat. These oviposition sites may provide nymphal habitat for this species as well.
Limiting factors
Habitat alteration and loss are the most significant threats. Local populations of this species may be impacted by habitat altering activities such as road construction, development, logging, disease control, and grazing which may degrade peatlands through increased erosion, sedimentation, and groundwater extraction. Decreases in groundwater availability, variability in precipitation, reduced snowpack, increased air and water temperatures, and intensified drought conditions are expected to have serious consequences for the long-term survival of this species and significantly impact its aquatic habitat. Stocking of non-native fish species for commercial or recreational purposes threatens aquatic stages of this species.
Data gaps
Assess distribution and determine range. Evaluate species’ dispersal and colonization ability. Document population status, dynamics, and trends.
Conservation actions
Survey suitable habitat for new populations. Monitor known populations and habitat. Maintain aquatic habitat features and hydrologic regimes. Limit disturbance.
Key reference or plan
Blackburn, M., and S. Foltz Jordan. 2020. Interagency Special Status/Sensitive Species Program (ISSSSP) Species Fact Sheet: Aeshna sitchensis. USDA Forest Service Region 6 and USDI Bureau of Land Management Oregon State Office. 31 pp. Read here
