Swift Forktail

On 23 April 2021, Erika and I took this photo of a mating pair of Swift Forktails at the McLane Creek Nature Trail about five miles south of home. Their large size (for a forktail), blue thoracic stripes and relatively dark abdomens certify identification of this early-flying damselfly. It almost looks like two males are in the “wheel position,” wherein a male grasps his mate behind her head, while she reaches her abdomen up to fertilize her eggs. But these are not two males. Rather the one on the bottom is an andromorph female. One hypothesis for some females looking like males is that the andromorphs are less hassled by aggressive males. Also present on our path were a few gynomorph females, like the one in the second photo. The advantage to looking like a female is that the males find you. But this might not be so important if you only have to mate once to fertilize enough eggs to last the season.

Dennis Paulson (2009) writes that Swift Forktails are often found on water lilies. I was surprised to read this passage, since all the Swift Forktails I have seen have been on dry land, far from water. But I must be getting old—I completely forgot about a Swift Forktail I photographed, also at McLane Lake, on water vegetation on 27 May 2019.  I found my old record, which I fortunately submitted to Odonata Central. Dennis, who patiently helps me with most of my Washington dragonflies, further writes that Swift Forktails “also perch on ground, rocks, and logs much more than other forktails. Females often found far from water…”