Thursday, December 19, 2013

A Late Darner

This year featured a number of dragonfly species that were flying well beyond their usual flight season. One example of this is the Variable Darner.  We see this species only occasionally at Cranberry Lake, and so it was a particular surprise to see one on October 29, nine days after the previous late flight date.

Here's the flight season of the Variable Darner in our area, including this new extension:

Notice that they start pretty late in the year, and go almost until November.

The next graph shows the Observation Percentage for the Variable Darner – that is, the percentage of all our observations of the Variable Darner that occur in a given month:

Over 60% of our observations occur in August.  As you can see, observations of this species are rather sporadic.

The Variable Darner is widely distributed in North America, as indicated in the following dot map:

Here's its distribution in the Pacific Northwest, which is fairly uniform:

The male Variable Darner that visited up on October 29 is shown below.  Notice the thin side stripes that actually break off into spots, the cream color on the 10th segment of the abdomen, and the simple appendages.

Another characteristic of this species is its propensity for perching on a wall or other flat vertical surface.  In this case it landed on the vertical concrete wall of the dam at one end of Cranberry Lake.  It's very common to see a Variable Darner perched in this way, but the other darners in our area generally land in bushes and trees.

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