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Dragonfly Science and Full Survey Data

Key Takeaways

Odonates – more commonly known as dragonflies and damselflies- give us important clues about a location’s water quality and ecosystem health. By monitoring dragonflies and damselflies every year, we can create a picture of the changes in composition and seasonality of local and migratory odonate populations. This can give us important information about changes in habitat quality as well as impacts of climate change. In 2016, JCWC volunteers began surveying dragonflies and damselflies in our watershed, and has continued each year. We have found a lot of valuable information from our surveys: The Johnson Creek Watershed is home to three of the five main species of migratory dragonflies in North America: the common green darner, variegated meadowhawk, and black saddlebags.

How to get involved: Help Johnson Creek Watershed Council document the distribution of dragonfly and damselfly species by participating in this year’s community science programs! Learn more here. Visit our iNaturalist page to check out the various species we have observed! Check our events page in June to sign up for our Dragonfly Orientation to take part in the surveys.

Dragonflies & Damselflies

When talking about dragonflies and damselflies, we often just say “dragonflies” for shorthand. But this leaves out the poor damselflies, which are closely related. It’s actually pretty easy to tell the two apart! Just look at three key features- their eyes, body, and wings.

  • Eyes: Dragonflies have much larger eyes than damselflies– in fact, most of a dragonfly’s head is actually its eyes (they have excellent vision)! Damselflies have a bit of space between their eyes.
  • Body: Dragonflies have bulkier bodies and are a bit shorter and thicker than damselflies, which tend to have narrow bodies.  
  • Wings: Dragonflies have their wings spread out horizontally while at rest, like an airplane, while damselflies fold their wings up and over or alongside their body when they rest.

Dragonflies and damselflies are a bit like cousins, and you can talk about both by using the special word odonate.

Odontos is a Greek word for tooth. Odonates are carnivorous as nymphs and adults, and the nymphs are characterized by toothed mandibles (jaws) at the end of a long, extendable mouth part. Odonates are compelling to learn about, and we still have much to learn.

Here are some other cool facts about them!

  • Dragonflies are predatory, capturing other insects in mid-flight
  • Dragonflies can spend several years underwater as larvae before emerging and transforming into winged adults.
  • The longest-known insect migration in the world is undergone by a dragonfly called the wandering glider.
  • In a migration that lasts for several generations, some populations of wandering glider travel 11,000 miles from India to southern Africa, twice the distance traveled by monarchs!

Survey Methods

The goal of these dragonfly surveys is to document:

  • Diversity, or the number of species found in the watershed
  • Abundance, or how many of each species might live in the watershed. 
  • Timing of species’ occurrence: When do adult dragonflies and damselflies first appear in our watershed? How might this compare with other local areas, or with other years? 

From June to October 2016, nine dedicated volunteers surveyed two locations (Westmoreland Park and Brookside Park) for odonates. In 2017, the surveys were repeated with 26 volunteers and a third location (Centennial Pond) was added!

Survey methods were developed by Celeste A. Searles Mazzacano of CASM Environmental. Celeste was our entomologist extraordinaire and scientific advisor on this project.

How were the surveys conducted?

  • Volunteers conducted surveys about every two weeks.
  • Odonate activity fluctuates a lot with temperature, cloud cover, wind, and more, so the timing of surveys would vary based on when conditions were optimal. 
  • Surveyors were armed with useful equipment, including a net, hand lens, dichotomous key for identifying odonates to the family level, and a field guide to identify them to the species level. Volunteer teams walked transects along a water’s edge at the sites, taking photos and netting individuals when possible. 
  • They recorded species, abundance, genders, and reproductive stage. Early in the season, our teams were especially careful to avoid netting newly-emerged odonates by looking out for a soap-bubble appearance on their still-delicate wings. 
  • Data was reported on iNaturalist

The more these surveys are repeated, the better we will understand these species!

2017 survey transects for Westmoreland Park (left), Centennial Pond (middle), and Brookside Park (right).

Survey Results

The most common species you may find throughout Johnson Creek are the Tule bluet damselfly (Enallagma carunculatum), the Pacific forktail damselfly (Ischnura cervula), and the Blue dasher dragonfly (Pachydiplax longipennis). 

The odonates pictured above had the highest observed abundance throughout our survey locations in 2017! 

Number of Odonate Species Observed (2017)

Westmoreland Park had the greatest odonate diversity out of the three sites, with a total of 21 various dragonfly and damselfly species observed in 2017. 

Odonate Diversity Fluctuations

Our results from each site in 2017 shows how the timing of odonates changes throughout the summer months. The graphs below display the number of different species observed at each survey date. This data can help us better understand when certain species (including migratory and non-migratory species) are present in Johnson Creek! 

What can we learn from our results?

Over the past two years, our surveyors have added new species records for our site locations, as well as for Multnomah County. Monitoring odonate assemblages can help us determine whether restoration goals are being met. 

The first year of surveys at Centennial Pond were conducted in the spring and summer of 2017, where an in-line pond is going to be removed in the future; our survey data will help us make comparisons about pre- and post- restoration habitat changes. For more information about the restoration project, contact Restoration Project Manager Chuck Lobdell at [email protected] 

Our results can also help us observe and understand changes in the historic ranges of odonates. A few years ago, Portland was the northernmost record for the Flame Skimmer (Libellula saturata); the dragonfly species is now documented in Portland regularly, and documented in southern Washington in 2017, showing a possible northward range expansion for this species. Global climate change has been implicated in geographical range expansion of dragonflies in Germany and Japan. Collecting more data here will help the scientific community be able to monitor changes in odonate dispersal.


Full Results Over the Years:

2016: Two new species (Autumn Meadowhawk and Black Meadowhawk) were added to the list of observed species in Multnomah County! Report2016

2017: Our 26 volunteers observed 23 odonate species in Johnson Creek! Four species new to the project list were observed!Out of our three survey locations (Westmoreland Park, Brookside Park, and Centennial Pond), Westmoreland Park had the greatest species diversity, with 21 odonate species observed!The survey location with the lowest habitat quality (Centennial Pond) had the lowest diversity, with 15 species observedIf you’d like all the scientific details, check out the full reports! 2017 Report

2018: During the 2018 field season, 195 observations of 21 odonate species were reported among three sites (15
dragonfly, six damselfly). Diversity was greatest at Brookside Wetlands, where 19 species were sighted (14
dragonfly, 5 damselfly); Westmoreland Park and Centennial Pond both had 13 species (9 dragonfly, 4 damselfly),
though the species list at the two sites was not identical (Jaccard Similarity Index = 0.625). The community at
Brookside was more similar to that at Centennial (Jaccard Similarity Index = 0.600) than to Westmoreland (Jaccard
Similarity Index = 0.524). Four of the five main migratory species in North America were observed using habitat at
these sites: Common Green Darner (Anax junius; all sites); Variegated Meadowhawk (Sympetrum corruptum;
Westmoreland, Centennial); Black Saddlebags (Tramea lacerata; Brookside, Centennial); and Spot-Winged Glider
(Pantala hymenaea; Brookside). P. hymenaea is a rare visitor in our region, and this sighting added a new species
to the project list in 2018.

The number of species seen among all sites in each month was lower in 2018 compared to previous years, and by
mid-summer many common species were either absent, or present in much lower abundances than expected.
Differences in weather are likely driving some community differences in 2018, as the average monthly temperatures. 2018 Full Report: Final-Report_Dragonfly-Surveys_CASM-Environmental-2018

2019:  A total of 243 observations of 23 species (17 dragonfly, 6 damselfly) was reported among all sites; these are more observations than in previous years, but a similar overall number of species (22 species in 2016, 23 species in 2017, and 21 species in 2018). Richness among sites was also more similar than in previous years, with 19 species at Brookside (15 dragonfly, 4 damselfly), and 18 each at Centennial (12 dragonfly, 6 damselfly) and Westmoreland (13 dragonfly, 5 damselfly). Odonate community composition was most similar at Westmoreland and Brookside (Jaccard Index = 0.71). The community at Centennial was more similar to that at Brookside (Jaccard Index = 0.68) than to Westmoreland (Jaccard Index = 0.59).

A total of 31 species has been recorded among all sites since the project began in 2016, representing three-quarters
of the species currently known from Multnomah County. Three new species were added to the project list in 2019:
Aeshna constricta (Lance-tipped Darner; Brookside), one of only three records in Multnomah County; Rhionaeschna
californica (California Darner; Westmoreland, Brookside); and River Jewelwing (Calopteryx aequabilis; Westmoreland),
one of only two records in Multnomah County. Three of the five main migratory species in North America were also
observed using habitat at these sites: Common Green Darner (Anax junius; all sites); Variegated Meadowhawk
(Sympetrum corruptum; all sites); and Black Saddlebags (Tramea lacerata; Brookside, Westmoreland).

Full Report: Final Report JCWC 2019

2020: Surveys were conducted between 8 April and 1 October 2020. The earliest surveys were at Westmorland Park
and Brookside Wetlands, where odonates were first seen on the wing on 8 April (Westmoreland; teneral male
Pacific Forktail) and 29 May (Brookside; Western & Pacific Forktail). Surveys at Centennial began on 19 June 2020.
There were 162 observations recorded cumulatively across nine dates at Westmoreland, 16 dates at Brookside,
and five dates at Centennial. Eighteen species (13 dragonfly, 5 damselfly) were reported among all sites in 2020.
This is less than in prior years (range = 21-23 species), likely due to 1. fewer surveyors; and 2. impacts of wind,wildfire, and smoke on insect populations. Individual site richness varied and was also lower at each site than in
any previous year, with 16 species at Brookside (12 dragonfly, 4 damselfly), 14 at Centennial (10 dragonfly, 4
damselfly; note that site richness in 2018 was also 14 species), and 12 at Westmoreland (8 dragonfly, 4 damselfly).

Odonate communities at Westmoreland and Centennial had many species in common (Jaccard Index = 0.80),
while Brookside differed more from both (Jaccard Index = 0.56 and 0.63, respectively). This may be influenced in
part by the fact that there were more survey dates at Brookside, enabling encounters of a greater number of
species. Paddle-tailed Darner (Aeshna palmata), Autumn Meadowhawk (Sympetrum vicinum), Blue Dasher
(Pachydiplax longipennis), and California Spreadwing (Archilestes californicus) were recorded only at Brookside in
2020 (though all have been seen at Westmoreland and/or Centennial in other years), while Vivid Dancer (Argia
vivida) and Western Pondhawk (Erythemis collocata) were absent from Brookside but present at the other two
sites in 2020.

Read full report: CASM Env 2020 JCWC Odes Final report