Monday, April 13, 2015

Happy-face On My Finger

I have many pictures of the Happy-face Dragonfly sitting on my finger.  I decided to convert one of them to a drawing.  Notice the paddle-shaped appendages – which are responsible for its official common name, the Paddle-tailed Darner – and the presence of a light-colored spot on the tenth segment of the tail (abdomen).


The official name, Paddle-tailed Darner, isn't particularly apt because a number of different species have paddle-shaped appendages.  For example, the Shadow Darner, Walker's Darner, and the Lance-tipped Darner all have appendages with a similar paddle shape.  This leads to confusion because people often think that paddle-shaped appendages must be distinctive to the Paddle-tailed Darner, and are surprised to find the same shape in other darners.

In addition, the use of "tailed" in the name is unfortunate, because "tail" usually refers to the abdomen, not the appendages.  As an example, the Common Whitetail has a white abdomen (tail); similarly, the Red-tailed Pennant has a red abdomen (tail).  On the other hand, the Brush-tipped Emerald has appendages (tips) that are brush shaped.  So, the Paddle-tailed Darner has a name that is not particularly appropriate – of course, I think it's official name should be the Happy-face Darner!

It's been a long time since I seen one of these guys, much less had one on my finger.  I'm looking forward to becoming reacquainted with them later this year.  In the meantime, here's a YouTube video slideshow of a variety of dragonflies on my fingers:  Slideshow.

Monday, March 30, 2015

Early-Season Report: Red-tailed Pennant

The Red-tailed Pennant is a common red dragonfly of the desert southwest.  In Arizona, where I am now, its flight season is said to begin in June.  Even so, I've been seeing them regularly in April the last couple years, and this year I saw one in my backyard just a few days ago.  It seems their early flight date should be moved up to March.

Here's a look at the Red-tailed Pennant, along with some of its more prominent field marks indicated with white text and arrows. The blue annotations indicate other features of interest.

A male Red-tailed Pennant, observed at the Gilbert Water Ranch.
Field marks for the Red-tailed Pennant.

Here's a slightly different view:


It seems a lot of animals are showing up at different times than usual these days – apparently the Red-tailed Pennant falls into that group.

The best thing about this observation is that this was the first time I've seen a Red-tailed Pennant in my backyard.  That's cool.  I hope I continue to see them!

Monday, March 23, 2015

The Whisperer Spoke

Betsy and I had a great time visiting Sedona and Flagstaff.  We enjoyed the beautiful countryside, and had lots of fun meeting fellow nature lovers.

Sedona, AZ, as viewed from near our hotel.  The "coffee pot" formation is on the right.

The San Francisco peaks near Flagstaff, AZ, with a light covering of snow.

Thanks to all who attended the dragonfly presentations – your enthusiastic response and excellent questions made the whole experience more enjoyable for everyone!

Tuesday, March 17, 2015

The Whisperer Speaks!

Greetings Dragonfly Enthusiasts!

The Dragonfly Whisperer will be speaking again tomorrow night (March 18) in Sedona, AZ, and again on Thursday night (March 19) at Flagstaff, AZ.  Here's the ad for talks:



Here's the handout for the talk.  Feel free to download it and print it on your own printer.


I hope to see you there.  Should be a fun evening.  Be sure to come up and say "Hi."

Monday, March 9, 2015

Early Season Dragonflies 2015!

Wow.  The 2015 dragonfly season is off to a great start!  It seemed a bit slow at first, when we failed to see dragonflies in Medford, Oregon or at the Sacramento Wildlife Refuge, but it picked up big time when we got to Southern California and Arizona.

We saw our first dragonflies at the Coachella Wildlife Refuge near Palm Springs, CA on March 4.  We always stop there on our way to Arizona, and generally see Vivid Dancers and nothing else so early in the year.  This time we saw the usual damselflies, but also good numbers of Spot-winged Gliders in feeding groups of 4 to 6 at a time.  Here are some photos of the odonates we saw at Coachella:

A male Vivd Dancer at the Coachella Wildlife Preserve.  Notice the little "arrowheads" on the side of the blue bands on the abdomen.
A Spot-winged Glider taking a rare rest.

Our next view of dragonflies occurred in Arizona on March 6.  We went to the Gilbert Water Ranch, near our home in Mesa, AZ, and immediately saw lots of odonate activity.  We first saw Familiar Bluets and Rambur's Forktails, then the dragonflies started to appear.  We spotted some Red Saddlebags along the shore (in fact we saw pairs in tandem laying eggs), and then some Roseate Skimmers, a Common Green Darner, a Mexican Amberwing, and a Variegated Meadowhawk.  The activity was constant, and at a high level.

Here are a few photos of the dragonflies seen at the Gilbert Water Ranch:

A male Familiar Bluet at the Gilbert Water Ranch.
A male Mexican Amberwing (right) entices a female to lay eggs in his territory.
A male Roseate Skimmer looking fresh and bright.
A male Red Saddlebags coming in for a landing.

Here's our species list for odonates so far this season:

Damselflies
Familiar Bluet
Rambur's Forktail
Vivid Dancer

Dragonflies
Common Green Darner
Roseate Skimmer
Mexican Amberwing
Variegated Meadowhawk
Red Saddlebags
Spot-winged Glider

Wednesday, February 25, 2015

Wing Whacking in Dragonflies

Wing Whacking
(Article for Argia)

Dragonflies use their wings in a variety of ways, and for a variety of purposes.  The most obvious, of course, is as a means of locomotion.  Even in flight, however, the wings can operate in a number of different ways – sometimes with the forewings and hindwings flapping in unison, and sometimes with them flapping out of phase. 

Dragonflies also spend a considerable fraction of their flight time gliding and soaring.  Sometimes they even “sky dive,” which is accomplished by holding their wings high above their body and dropping briefly in free fall (Walker, 2013a).  Wings, it seems, are as flexible in their various modalities as they are in their constitution.

Other interesting uses for wings have also been observed.  For example, “wing grabbing” is a behavior exhibited by some males as they attach in tandem with a female (Walker, 2013b).  In addition, “spin-drying” at 1,000 rpm is a fascinating behavior that is done to dry off after a series of “splash-dunks” (Walker, 2011a, 2011b).

In this article, I report on another way that dragonflies use their wings, which I refer to as “wing whacking.”  So far, this behavior has been observed in Paddle-tailed Darners (Aeshna palmata) and White-faced Meadowhawks (Sympetrum obtrusum), but it seems likely that many other species will be found to display similar behavior.

The Basics of Wing Whacking
Wing whacking occurs when a pair of dragonflies are actively mating in the wheel position.  An example of a pair of Paddle-tailed Darners in the wheel position is shown in Figure 1.  The mating process can last for several minutes, and can involve a good deal of activity.  Sometimes the female appears to become a bit fidgety, and will start to move about.  When this happens the male lifts his abdomen upward a bit, and then “whacks” the female on either side of her head with his wings.  The result of the wing whacking is that the female settles down and mating continues.


Figure 1  A pair of Paddle-tailed Darners mating in the wheel position.  If the female starts to fidget, the male will calm her down with a few well-placed wing whacks.

In a typical situation, the male whacks the female 3 to 4 times in rapid succession for about 0.15 s, as determined by counting frames in a slow-motion video shot at 240 frames per second.  The male then rests for about 0.18 s before resuming with a second burst of 3 or 4 whacks.  Two rounds of wing whacking are sufficient to restore calm in the cases I’ve observed so far.  Here's a video example:

video

The frequency of wing whacks – that is the number of whacks per second – can be determined from the slow-motion videos.  I have been able to analyze four separate wing-whacking events so far, and in each case the whacking frequency has been determined.  The results are presented in Figure 2 for each of the four events.  Notice that the average whacking frequency is about 25 whacks per second, which is slightly slower than the typical wing beat frequency in flight of about 35 beats per second.


Figure 2 The frequency of wing whacking, in whacks per second, for four different events that were analyzed with slow-motion video.

The same basic wing-whacking behavior has been observed when a single male attempts to separate a mating pair.  In this case, the interloping male approaches the pair and attempts to land on the thorax of the mating male.  As it comes in for a landing, the male in the wheel position whacks the other male with its wings, just as it would do with a fidgety female.  In the cases I’ve observed, the wing whacking has been effective at repelling the unwanted advances.

Post-Whacking Quivering
An interesting and unexpected element of the wing-whacking behavior is observed after the female has settled down.  It would seem that once the goal of restoring calm has been achieved, the male would simply rest.  Instead, he “quivers” his hindwings – and the hindwings only – much like the shaking motion of a Quaking Aspen leaf.  Here's an example:

video

The quivering motion of the male’s hindwings is observed to last for about 0.25 s to 0.50 s, and is fairly rapid, clocking in at about 55 vibrations per second.  The purpose of the quivering is unclear.  Perhaps it serves as a signal to the female that the male is prepared to resume wing whacking if necessary.

Questions for Future Research
Wing whacking joins the ranks of interesting wing behaviors displayed by dragonflies.  It will be interesting to see what other species show a similar behavior, and how many species use a similar whacking motion to repel unwanted males.

Finally, it should be noted that to the human eye it appears the female fidgets, and that the male reacts and calms her down, as described above.  Another possibility, however, is that the male is actually the one who is fidgeting as he conducts the important business of mating and sperm transfer.  Perhaps the wing-whacking is simply a manifestation of the male trying to retain control of the female during active mating.  Additional observations should shed more light on these questions.

Acknowledgements

I would like to thank Betsy Walker for help with these observations.

Literature Cited

a. Walker, J. S. 2013.  Skydiving Dragonflies.  Argia 25(1): 20-21.

b. Walker, J. S. 2013.  Attaching in Tandem: The Role of “Wing Grabbing” and “Wing Pulling."  Argia 25(4): 28-29.

a. Walker, J. S. 2011.  Spin-Dry Dragonflies.  Argia 23(3): 29-31.

b. Walker, J. S. 2011.  Splash-Dunk Analysis, 2011.  Argia 23(4): 29-30.

YouTube Material

Wing whacking in a pair of Paddle-tailed Darners:

Quivering motion of the hindwing of a male Paddle-tailed Darner:

Saturday, February 14, 2015

Happy Valentine's Day!

Happy Valentine's Day from the Dragonfly Whisperer and the Happy-face Dragonfly:



In addition, Happy Valentine's Day wishes from the Calico Pennant, which has a series of heart-shaped spots on its abdomen.  Here it is:


A beautiful dragonfly, and very much in the Valentine's Day spirit.  Perhaps it's name should be changed to the Valentine's Pennant.