Sunday, October 28, 2012

A Useful Field Mark For Darners: The Dorsal Stripe On Abdominal Segment 2

Field marks are the bread-and-butter of birding and dragonflying.  Having a good suite of field marks for a particular species is important in accurate identification, because a single field mark can be variable or hard to see in a particular situation.

For example, when identifying Hutton's Vireo it's useful to keep in mind a variety of good field marks that distinguish it from the Ruby-crowned Kinglet.  The vireo has light-colored lores, wing bars that lack a dark border, and black feet (as opposed to the yellow feet of the kinglet.)  It's common for only one or two of these field marks to be visible on a given individual as it hops from branch to branch in the bushes, so having a number of field marks to work with can be quite helpful.

With that in mind, a similar situation occurs when identifying certain darners that are quite similar in appearance.  For example, Shadow Darners lack blue spots on the tenth segment of their abdomens (S10), whereas Paddle-tailed Darners (Happy-face Darner) do have blue spots on S10.  The tenth segment of the abdomen isn't always easy to get a look at, and so other field marks are useful, like a strong facial line in the Paddle-tailed Darner that is lacking in the Shadow Darner.

Another field mark that I find to be useful for a number of different darners is the blue stripe that appears on the dorsal surface of S2.  For orientation, the "wasp waist" in male darners is S3, and S2 is the bulbous segment closer to the thorax.  Here is a photo comparison of the dorsal stripe in four different, but similar-looking darners.

A comparison of blue dorsal stripes on four different darner species.  The stripes vary from thin and straight to broad and spindle shaped, to half a stripe, to a stripe that is wider at the base that the top.

The blue dorsal stripe is straight, thin, and fairly uniform in the Paddle-tailed Darner.  In the Shadow darner it is broad and spindle shaped – almost like a chess piece.  Only half a stripe appears on the Variable Darner, and Walker's Darner has a stripe that is wider at the base than at the top.  I need to work more on these to see how consistent they are, and how they can be extended to other species as well.

Here's a gallery of photos showing these darners.  Check out the dorsal stripes as an additional means of identification:

Paddle-tailed Darner (Happy-face Darner).  Note the thin, straight, uniform dorsal stripe on S2.

Again, a nice Paddle-tailed Darner (Happy-face Darner).  You can't see S10 in this photo, but the dorsal stripe on S2 is quite definitive.

A triplet of free-range darners.  From lef to right we have Shadow, Shadow, Paddle-tailed.  These dragonflies were never captured – simply lifted one at a time onto my fingers.  They were free to fly away at any time.

A Shadow Darner shows off his broad dorsal stripe on S2.

Two free-range Shadow Darners.

A Variable Darner sports just half a stripe on S2.

Walker's Darner has a dorsal stripe on S2 that is wider at the base than at the top.

A closer look at the dorsal stripe on S2 for a Walker's Darner.

I've enjoyed using this field mark, and will continue to apply it and test it out for consistency and dependability.

Thursday, October 25, 2012

Sky-Diving Dragonflies

Dragonflies are known for their impressive aerobatic skills.  They can turn on a dime, hover with precision, plow into the water to create a splash-dunk, and even spin-dry at 1,000 rpm in mid flight.  They're amazing flying machines.

A couple days ago, Betsy and I were watching some late-season darners at Cranberry Lake when one made an impressive maneuver and caught a fly right in front of us.  The darner was flying straight and level at about eye level.  It suddenly noticed a fly just above and slightly behind it, and it came to an abrupt stop.  The darner hovered with its body almost vertical, and as it hovered it rotated and repositioned itself slightly so that it was on a direct line with the fly.  Once in position it accelerated and captured the fly in the blink of an eye.  What a display of precision, patience, and power.

All of this is well and good, but did you know that dragonflies can sky dive?  Well, at least that's what I call it.  What they do is bend their abdomen upward, raise their wings up over their body, and then drop briefly in free fall.  They look like a skydiver with arms and legs pointing upward as they plummet toward Earth.  Here are a few photos of a sky-diving darner taken from a slow-motion video:

A darner (probably a male Paddle-tailed Darner) just before doing a sky dive.

The sky dive is beginning, as the darner raises its abdomen.

Now abdomen and wings are raised upward.  At this point the darner drops briefly in free fall.

The same darner is getting ready for a second sky dive.

There goes the abdomen pointing upward.

Now the wings follow the abdomen in pointing upward, and the darner drops downward.

Here the darner is pulling out of his brief free fall.

Here's the video from which these screen captures were taken.

video

So what's going on with sky diving – why are they doing it?  It's hard to know for sure.  At first I wondered if they might be losing altitude quickly, like whiffling geese that sometimes even turn upside down as they drop down to land.  A good link for photos of whiffling geese is the following:

http://clives.shawwebspace.ca/photos/view/whiffling_geese_/

With more observations this explanation seems less and less likely – the darners are able to increase or decrease altitude much more quickly than they do while gliding in free-fall sky diving.

It may be that they are cleaning their wings or abdomen.  Sometimes a perched damselfly will be seen to arch it's abdomen upward – it appears to be rubbing the abdomen against the wings in a cleaning action.  Darners may be doing the same sort of thing, only in mid flight, as they do so many things in their life.  Sky diving isn't very common, so it may be a while before we know more about its purpose.

Friday, October 19, 2012

A Darner In The Bush Is Worth Two In The Hand

A couple days ago there was a brief break in our autumnal rains, and I took advantage of it by zipping up to Cranberry Lake for a few minutes.  It was cool there, 55 ˚F, and breezy – only a bit of sun filtered through the clouds.  Still, five or six darners were flying over the water and checking for females along the shoreline.  In addition, six or seven darners were perched in the bushes, perhaps hoping for a little more sun, and a few Autumn Meadowhawks were perched on the ground.

I decided to do some dragonfly whispering.  I went up to one of the Happy-face Darners (Paddle-tailed Darner) in the bushes and lifted him onto my finger.  Remember that this was a "free-range dragonfly", completely free to take wing at any time.  It had never been caught or manipulated in any way – I simply lifted it up on my finger, which took the place of a branch.  Here's what he looked like as he sat happily on my hand.

A male Happy-face Darner (Paddle-tailed Darner) resting on my hand.  Such a charming fellow.  (The white spots on the eyes are reflections of the Sun.)

Here are a couple more photos of him.  If you toggle back and forth between the photos you'll get an idea of what it looks like as he cocks his head.




After the darner flew off to go about his busy day, I decided to lift another Happy-face Darner onto one finger, and then while he was going along for the ride, lift a Shadow Darner onto a second finger.  This makes for a nice comparison between these two similar species.  Again, remember these are "free-range dragonflies".

A male Happy-face Darner (Paddle-tailed Darner) on the left, and a male Shadow Darner on the right.  The Happy-face has blue on the tenth segment of its abdomen, but the Shadow Darner's tenth segment is black.  In addition, the blue spots are large, and actually get a bit larger, as you go toward the end of the Happy-face abdomen.  In the Shadow Darner, the blue spots get smaller and eventually disappear altogether.

Here's another view.  In this case, notice the top of segment 2 of the abdomen.  For orientation, segment 3 is the one that is narrow – almost like a wasp waist.  Segment 2 is the large, bulbous segment that is closer to the thorax.  On the top of this segment, the dorsal surface, there is a blue stripe in both species.  The blue stripe on the Happy-face Darner is thin and uniform in width.  In contract, the blue dorsal stripe on the Shadow Darner is broad and nonuniform.  It looks a bit like a chess piece, or the profile of a tree.

Happy-face Darner (left) and Shadow Darner (right).  Notice the difference in the blue dorsal stripe on segment 2 of the abdomen.  It is thin and uniform in the Happy-face, broad and nonuniform in the Shadow.

The blue dorsal stripe on segment 2 is a field mark that I haven't seen mentioned in any of the field guides, but I find it quite helpful.  I often see a darner in the bushes, and a leaf blocks a view of the tip of the abdomen.  No worry – if I can see segment 2 I'm in business.

Tuesday, October 16, 2012

We're Off To See The Darner – Walker's Darner

Edmund Murton Walker (1877-1969) was a Canadian entomologist, zoology professor at the University of Toronto, and an assistant director of the Royal Ontario Museum.  His specialty was dragonflies, and it was for him that Walker's Darner was named.

I'm not related to Edmund Walker, as far as I know, but the fact that one of the mosaic darners carries the name Walker has always been a fun connection with my interests.  This is especially true since Walker's Darner is a close relative of the Paddle-tailed Darner (Happy-face Darner), to which I have such a special connection.  Thus, I've long looked forward to seeing a Walker's Darner.

The problem with seeing a Walker's Darner for me is that they had never been seen in Washington.  Their range is mostly restricted to California, with just a few isolated observations in Oregon.  In addition, they don't start flying until mid-summer, when I'm usually in Washington watching Happy-face Darners splash-dunking and spin-drying.

Last week, Betsy and I decided to take a short road trip to enjoy the good weather while it was still with us.  Just minutes before we left I checked OdonataCentral to see if we might be going near any of the observation sites for Walker's Darner in Oregon.  I knew there were a couple sites along the Columbia Gorge, and I thought we might visit one of them – even though it was too late in the season according to some of the field guides.  I was surprised, then, when I saw a new dot on the Walker's Darner map in Washington State, on the Washington shore of the Columbia River!  It was a state record for Walker's Darner, and it was observed just a few weeks before I checked, in the last half of September.  We decided to give the location a try, even though we would be getting there in the second week of October.

OdonataCentral provided details of the location.  It was near White Salmon, on Old Highway 8, about a mile north of the highway on Major Creek Road.  There's a sharp bend in Major Creek Road where a small creek passes underneath, and that's where they were seen.  We arrived there at about 2:00 pm, and just as I was getting out of the car a darner flew by.  We followed its flight until it landed and, sure enough, it was a Walker's Darner.  This was on October 9, 2012, a new late flight date for both Oregon and Washington.

So fun to finally see Walker's Darner, and in Washington to boot, where it had never been seen before.  Below are a couple photos from Major Creek Road.  The darner is perched high in a tree, making photography difficult, but the photos do show everything that's needed for a confirmed sighting.  We've entered our observation with OdonataCentral – it's listed in their records as OC#382101.


Walker's Darner, male, perched high in a tree.  Notice that the side stripes on the thorax are whitish, compared with yellowish stripes on the Paddle-tailed and Shadow Darners.

Walker's Darner.  Notice the paddle-shaped appendages and whitish side stripes on the thorax.  In addition, the tenth segment of the abdomen (S10) is mostly black, but with a light-colored posterior edge.  In the Paddle-tailed Darner, S10 is covered with blue, and in the Shadow Darner S10 is usually completely black.  Notice also the blue dorsal stripe on S2; it is wide at the base and narrow at the top.  In the Paddle-tailed Darner this stripe is uniform and narrow, and in the Shadow Darner it is broad and shaped somewhat like a vase.

Walker's Darner.  A good look at the whitish side stripes on the thorax.

Betsy took a quick picture of me to document the time and place of our first sighting of a Walker's Darner.

Sunday, October 14, 2012

Field Trip: Day II

We had another great day for dragonflies on Saturday, October 6.  The weather was perfect, the dragonflies were active, and the company to share it with was wonderful.  Thanks to all who joined us for making it a memorable field trip.

Here's the species list for the day:

Northern/Boreal Bluet
Pacific Forktail
Blue-eyed Darner
Paddle-tailed Darner
Shadow Darner
Variable Darner
Autumn Meadowhawk

The Autumn Meadowhawks are the red ones, the ones who love to land on people.  Remember the haiku for these guys, which you can see here:

http://thedragonflywhisperer.blogspot.com/2012/09/autumn-has-arrived.html

Also, results from day one can be found here:

http://thedragonflywhisperer.blogspot.com/2012/10/field-trip-day-i.html

The photos below show the lovely weather, and the great dragonfly interactions we enjoyed.

Enjoying the company of an Autumn Meadowhawk.
A photographic moment.  She had just lifted this Autumn Meadowhawk from its perch on the fencepost.
Getting a good close look.  So nice to be able to interact with these wonderful creatures.

Thanks also to Jerry Eisner for sharing some of his photos from the day with us.  Here they are:

With a little dragonfly whispering, this Autumn Meadowhawk was convinced to spend some time perched on a friendly finger.  (Photo by Jerry Eisner.)
This is a female Autumn Meadowhawk.  Notice the large "egg scoop" projecting downward from near the tip of the abdomen.  The scoop is used to hold a drop of water into which the female deposits her eggs.  For more on the egg-laying process, see the last two photos below.  (Photo by Jerry Eisner.)
Time for a good look.  (Photo by Jerry Eisner.)
The red dragonflies really do perch on shoulders.  (Photo by Jerry Eisner.)
Beautiful flight shot of two darners.  (Photo by Jerry Eisner.)
Another great flight photo.  It's wonderful how photographs can capture a moment in time like this.  (Photo by Jerry Eisner.)
A pair of darners hooking up into the wheel position in mid flight.  (Photo by Jerry Eisner.)
A painterly photo showing a pair of Autumn Meadowhawks in tandem.  The female's abdomen is dipped into the water to acquire a drop of water.  (Photo by Jerry Eisner.)
After the female gets a nice drop of water, the pair hovers for about a second while she lays eggs into it.  The pair then smashes into the shoreline vegetation to dislodge the drop, with the eggs it contains, and ready themselves to repeat the process.  (Photo by Jerry Eisner.)

Friday, October 5, 2012

Field Trip: Day I

Today was the first of our two field trips to see late-season dragonflies at Cranberry Lake.  It's a great time to see darners and Autumn Meadowhawks.  Lots of activity of various types, and beautiful weather and scenery to boot.

For example, we had some very good views of the Happy-face Darner (Paddle-tailed Darner) perched in the bushes.  We also saw perched Shadow Darners and Variable Darners.  They looked great through the spotting scope, and lots of good pictures were taken as well.

In addition, we saw 10 splash-dunk events, most of them followed with a nicely visible spin-dry.  In some cases we could see droplets shooting off during the spin-dry, in other cases we saw the droplets spraying across the smooth surface of the lake.  It was such a warm, toasty day that we envied the dragonflies, and were tempted to so a little splash-dunking of our own.

The Autumn Meadowhawks were their usual friendly selves, perching on just about everyone at one point or another.  Even people just out for a walk found themselves in the midst of dragonfly appreciation day!  Here are a couple shots of Libby with a male Autumn Meadowhawk on her hat and just taking flight.

A male Autumn Meadowhawk basks in the sun on Libby's hat.

A little while later he decided to take off, probably to look for a mate.

Thanks to all who attended.  Betsy and I had a great time sharing our love of dragonflies.

Happy Dragonflying,

Jim & Betsy Walker

P. S.  Ronan Ellis was kind enough to share some of his pictures from this field trip with us.  Thanks, Ronan!  Here they are:

Red dragonfly on a shoulder.  (Photo by Ronan Ellis.)
Red dragonflies like hats as well.  (Photo by Ronan Ellis.)
Nice place to bask in the sun.  (Photo by Ronan Ellis.)
Giving a dragonfly a hand.  (Photo by Ronan Ellis.)
Paddle-tailed Darner, also known as the Happy-face Darner.  (Photo by Ronan Ellis.)

Thursday, October 4, 2012

Variegated Meadowhawk

The Variegated Meadowhawk is an interesting species for a number of reasons.  First, it's color pattern, particularly on the abdomen, sets it apart from all our other meadowhawks and is the reason for its name.  Second, it is one of a small number of dragonflies known to migrate.  Large flights heading south in the fall have been observed along the west coast.  Betsy and I have seen mature pairs laying eggs as early as March 9 in southern Oregon, when no sign of emergence was apparent.  These individuals had probably migrated north from overwintering sites in the southwest.

Here in the Anacortes area, we see Variegated Meadowhawks on a hit-or-miss basis.  We never know where one will show up, and there is no location in our area where they are seen consistently.  We've seen them in a variety of different situations, including Washington Park in mid November.

Yes, the Variegated Meadowhawk is an oddball – but it's always a delight to see with its wonderful colors and patterns.  This summer we saw one at Smiley's Bottom for the first time.  It was a young male that was still mostly yellow – it will become reddish with age.  Also note the white stripes on the side of the thorax, with a yellow dot at their lower end.  With age these stripes will fade away, but the yellow dots will remain.  Also, notice the lavender color of the eyes.  The eyes will turn increasingly reddish with age, but there will always be a lavender component to the color.

A young Variegated Meadowhawk at Smiley's Bottom.

Here the meadowhawk tilts its head to point the dorsal fovea to the left for a better view in that direction.  Notice the lavender color of the eye, and the nice array of pseudopupils.

Wednesday, October 3, 2012

Field Trip, Cranberry Lake, Friday & Saturday October 5 & 6, noon to 2:00 pm both days

Did you think dragonfly season was over?  Well, not so fast.  They're still out and about, bringing enjoyment and delight to those who look for them.

In fact, this is the prime time to see Happy-face Darners and to observe splash-dunk/spin-dry behavior.  And the prime location for both of these activities – dragonfly central, if you will – is Cranberry Lake in little old Anacortes.

To take advantage of this opportunity, Betsy and I are offering a field trip this Friday and Saturday (October 5 & 6) at Cranberry Lake.  The way it will work is as follows:

Betsy and I will be at Cranberry Lake, adjacent to the parking lot, from noon to 2:00 pm on Friday and Saturday.  If you would like to join us and our dragonfly friends, just drop by any time during those hours – we'll be in the same location the entire time.  Feel free to arrive and depart whenever you like.

We'll be looking for perching dragonflies (often 3 – 5 will be perched at a time), and thus binoculars, cameras, and spotting scopes will be most advantageous.  We'll also be scanning the lake for splash-dunk events and the spin-dry that follows.  Lately, we've been seeing one event roughly every 5 to 6 minutes, though it varies from day to day.  A few days ago we saw a record of 8 splash-dunks in a row, followed by a nice spin-dry with water droplets flying off in all directions.

To get to Cranberry Lake (in Anacortes), head toward the San Juan ferry terminal.  About halfway between downtown Anacortes and the terminal turn onto Georgia Street.  A couple blocks up the hill you'll see a gravel road on the right.  That road takes you directly to the parking area.  Here's a map:


What dragonflies are flying this time of year?  The most numerous are Paddle-tailed Darners (Happy-face), but we're also seeing Shadow Darners and Variable Darners.  In addition, Autumn Meadowhawks are showing up in increasing numbers.  Here's a link to a haiku about the Autumn Meadowhawk: http://thedragonflywhisperer.blogspot.com/2012/09/autumn-has-arrived.html.

Below are photos of the dragonflies mentioned above, along with captions pointing out the field marks that are useful for identification.

A male Autumn Meadowhawk.  Notice the prominent hamules at the base of the abdomen.  This individual still has traces of yellow because it is just past its teneral stage where it was all yellow.  When fully mature it will be almost solid red, with virtually no distinguishing stripes or spots.
A female Autumn Meadowhawk.  The female is a brownish red, not as bright as the male.  Notice her prominent "egg scoop" near the tip of the abdomen.  This is a distinguishing feature for this meadowhawk.
A male Paddle-tailed Darner (Mr. Happy-face).  Notice the blue spots on the abdomen that go all the way to the last segment.

The Paddle-tailed Darner (Mr. Happy-face) has beautiful blue eyes, and a charming face.
A male Shadow Darner.  Notice that the blue spots on the abdomen get smaller near the tip, vanishing completely on the last segment.  The front stripes on the thorax are a bit greenish, compared with the yellowish front stripes on the Paddle-tailed Darner.

The Shadow Darner has a bit of a happy face himself.
A male Variable Darner.  Notice that the side stripes on the thorax are very thin, and even break off into two segments.  The front stripes are quite small.  Also, notice that the last segment of the abdomen has cream-colored spots, and that the appendages are not paddle shaped.

The Variable Darner is clearly related to the Happy-face Darner.

That's it for now.  We hope to see you there!

Happy Dragonflying,
Jim and Betsy Walker