Tanner Springs Park is not your textbook city park. It’s a great example of melding “wild” natural, “tamed” natural, and unnatural elements in complementary ways. About two-thirds of the park are what I would describe as unkempt—which is a good thing. It isn’t all manicured lawns, ornamental vegetation, and fountains. Check out the view at Google Maps.
There’s a pond with lots of emergent vegetation along one edge which transitions into an upland landscape of native plants and gravel paths. The pond itself is equipped with a substantial boardwalk so you can get right out on the water and easily see what’s using it. The pond isn’t the only water feature here: there are even tiny streams which flow down from the upper (west) side of the park out of artificial springs (pumped from the pond and treated within the park before emerging from the springs—apparently a first for a Portland park).
|An artificial spring and source of one of the tiny streams flowing into the pond downslope.|
But I’m really here to talk about odonates—which are here, of course, because of the water features. And even though this little man-made wetland is enveloped by an urban landscape, I found a decent variety of odonates largely thanks to the unmanicured state of pond- and streamside vegetation.
The most abundant species were the damselflies: Pacific Forktail (Ischnura cervula), Western Forktail (I. perparva), and Vivid Dancer (Argia vivida). The forktails were at the pond and feeding in the adjacent upland vegetation, while the dancers were almost exclusively at the tiny streams, perching on rocks or adjacent pathways. I was surprised that I didn’t see a single Tule Bluet (Enallagma carunculatum)—a very common and widespread species in this region.
|Female Western Forktail (Ischnura perparva).|
|Male Vivid Dancer (Argia vivida). This species is certainly at Tanner Springs Park only because of the little spring-fed streams.|
|Male Eight-spotted Skimmer (Libellula forensis).|
|Male Cardinal Meadowhawk (Sympetrum illotum).|
|Female Western Pondhawk (Erythemis collocata).|
|A darner exuvia, presumably California Darner (Rhionaeschna californica).|
If you ever find yourself in The Pearl on a warm, sunny mid-day during the odonate season, I encourage you to spend a little time at Tanner Springs Park. I’ll do my best to stop by at least a couple more times as the season progresses to see what is flying.