Thursday, March 31, 2011

The Pacific Northwest's First Fliers

Usually around mid-February my mind becomes occupied with thoughts of when the weather will turn sunny and warm enough to bring out flying odonates in my area (Vancouver, Washington). My general rule-of-thumb conditions for the first flying odonates of the spring are about three consecutive days of around 60° F or more and at least partially sunny skies. Of course, a few odonates could be flying before those conditions are met, but it’s what I look for before I start thinking, “There must be something flying now.”

This year, unfortunately, the spring weather has been unusually cool and wet—just across the Columbia River from me, Portland, Oregon has broken its latest first 60° (F) day record (which still has not been attained as of this writing) and its number of March days with measurable rainfall record (currently 28 days). This has been a tough spring for me.

Even though odonates are late this spring, let’s be prepared for those first few warmer, sunnier days which must come eventually. I promise they will. They have to, right? What should you look for? Below are photos of some of the earliest fliers in the western Oregon/Washington region, roughly in the order that I expect to see them. Exceptions certainly occur, and the line up may vary depending on where you are and the types of places you visit. There are a couple of other contenders for this group of first fliers, but I went with the five species that I think of as most likely.

Pacific Forktail (Ischnura cervula): In my last post, I shared a photo of a male of this very common and widespread species. Females are quite variable depending on their maturity and whether they are gynochromatic or androchromatic—“female-colored” or “male-colored”, respectively. Below is an immature gynochromatic female with its extensive pinkish coloration on the head and thorax and single blue segment near the end of the abdomen.

Swift Forktail (Ischnura erratica): This is the biggest member of the genus in the Northwest with bold blue and black stripes on the thorax and typically some extra blue near the end of the abdomen. Look for it at ponds in forested areas west of the Cascades.

Variegated Meadowhawk (Sympetrum corruptum): This is the migratory species occasionally seen in large numbers at coastal locations during August and September when the conditions are right. Presumably, the earliest spring adults are migrants from the south. Mature individuals look dusty orange from a a distance, but up close you will see an intricate pattern of dull reds, browns, yellow, and white.

Cardinal Meadowhawk (Sympetrum illotum): Another meadowhawk, but unlike the previous species, mature males are about as red as red gets. They simply glow and are very distinctive. (Working these images on my laptop, I’m not sure that I have the saturation right, but you get the idea.) They even have an amber wash over the basal portions of the wings.

Tule Bluet (Enallagma carunculatum): Like the Pacific Forktail, this species is very common and widespread, and can be seen at just about any fresh water wetland that has at least some emergent vegetation. There are several species of Bluet in the Northwest and they all superficially look like this, but this is the ubiquitous species of lower elevations west of the Cascades.

Have you seen any odonates yet this spring?


Post a Comment