Wing Beats in Egg-Laying Cardinal Meadowhawks

Cardinal Meadowhawks lay eggs while the males and females hover in tandem—this is how the male guards "his" female in this species. Here's a photo of a pair of Cardinal Meadowhawks hovering in tandem over an egg-laying site:



They hover for a second or two as the female gets an egg ready to be laid, then they dip down and drop off the egg. Here's a short video clip showing an egg-laying dip:

This video was shot at 240 frames per second, and a frame-by-frame analysis reveals a number of details of the tandem flight. First, the wingbeat frequency during this hovering flight is approximately 48 beats per second. That's a blur in real time, but in the slow-motion video you can follow each individual wing beat.

In addition, it's possible to see how the wing beats of the male and female are related to one another. One might think they flap in sync, but that's not the case. Alternatively, one might think they flap independently, but again, this is not the case. What they do is the following:

(1) The female's hindwings flap first.

(2) After 2/5 of a cycle, that is 144˚ of phase later, the female's forewings flap in unison with the
      male's hindwings. This is the key aspect of the hovering flight.

(3) The male's forewings flap 1/5 of a cycle (72˚) later.

(4) Finally, 2/5 of a cycle (144˚) later the female's hindwings flap for the next cycle.

There's a definite relationship between how the male and female flap, it's just not what one might imagine.

Here's a plot that shows the wing positions for both the male and female as a function of time for two cycles:



This same type of phase relationship between the male and female has been seen in Red-veined Meadowhawks. It will be interesting to see how widespread this behavior is among other species.

I Heart Heart Lake

We had a great time at Heart Lake a few days ago.  The lake gets its name from its very rough heart shape, as can be seen in the following map:

Heart Lake (center, bottom) in relation to downtown Anacortes.

In addition to the numerous Western Pondhawks that were there a couple days ago (see this post), we also observed a number of other dragonflies, including Blue Dashers and Eight-spotted Skimmers.

Perhaps most striking was the Cardinal Meadowhawk, with its intense red colors showing off nicely in the bright sun.  Here's an example of one of the males:

Male Cardinal Meadowhawk at Heart Lake.

In this next view you can see what I regard as its best field mark, the intense concentration of red color near the wing bases.

Male cardinal Meadowhawk.  Notice the dark red, opaque regions in the wings near the base.  An excellent field mark.

This field mark is completely diagnostic, and visible from almost any angle.  I'm always surprised field guides don't make a bigger deal of it.

Notice also the intense red color on the abdomen.  It almost over saturates the eyes.

The Cardinal Meadowhawks were also laying eggs, which they do while attached in tandem.  Here's an example:

Cardinal Meadowhawks laying eggs in tandem.  The female dips the tip of her abdomen in the water to deposit her eggs.

While this pair was laying eggs, a lone male was trying to break them apart so he could replace the current male, as can be seen below.  It didn't work, though he was pretty persistent.

A lone male Cardinal Meadowhawk unsuccessfully attempting to break apart an egg-laying pair.

Dragonflying at Mount Shuksun

On October 17, 2011, Betsy and I went to Picture Lake near Mount Baker.  Picture Lake is just before you get to the Mount Baker ski area, and it provides an incredible reflected view of Mount Shuksun.  A little later in the season the fall colors would be more prominent, yielding an even more impressive view.

Betsy, with Picture Lake and Mount Shuksun in the background.  This picture was taken shortly after we arrived, when there was still a bit of fog near the summit of Shuksun.  The temperature at this point was a brisk 46 ˚F, but the sun and lack of a breeze made it feel quite comfortable.  It warmed up during the time we were there, and by lunchtime it was 64 ˚F.

This is me at Picture Lake a little while later after the fog had burned off.  When we first arrived we didn't see any dragonflies to whisper to, but shortly thereafter the activity was pretty good.

The greatest activity that day was provided by the Ringed Emeralds.  The first one we saw was this dead male found along the shoreline.  A darner helped us find it by stopping on his patrol of the shoreline to check it out more carefully – in case it might happen to be a female darner.  The Ringed Emerald has an iridescent green thorax, green eyes, and thin white rings at the base of each abdominal segment.

We saw a few darners at the lake.  All that we could see well were Paddle-tailed Darners – Mr. Happy Face.  

The Ringed Emeralds were plentiful as the air warmed up a few degrees.  You could see them everywhere along the shoreline: pairs flying in tandem; males chasing females and other males; females laying eggs with males hovering nearby for protection.  Here a female dips her abdomen into the water to deposit eggs (water temperature was 46 ˚F).  

The water was so clear that I spent some time looking to see if I could spot the eggs the female was laying.  With a little practice I could.  The eggs came out in a small mucus string of maybe 6 or 8 greenish eggs, a lot like miniature frog eggs.  Strings start out in a tight ball, but then twist and straighten out as they drift slowly to the bottom.