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 continued the surveys again in 2017. We have found a lot of valuable information from our surveys:
If you’d like all the scientific details, check out the full reports!
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!
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.
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!
The goal of these dragonfly surveys is to document:
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?
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).
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!
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.
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.
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