Tuesday, February 28, 2012

A Swarm of Meadowhawks

Recent reports of mass gatherings of dragonflies make it seem there is “something in the air” when it comes to events like these.  Large numbers of baskettails have been observed in Canada, and a large gathering of Striped Meadowhawks was recently seen in Oregon.

In my case, the dragonflies involved were Autumn Meadowhawks.  These friendly dragonflies, which like to land on people, are a common sight at Cranberry Lake in Anacortes, Washington late in the season.

Betsy experiences a red dragonfly on the shoulder, and a second one on her hat.  Both dragonflies are male Autumn Meadowhawks, the friendliest dragonfly we know.

Autumn Meadowhawks are well described by a famous haiku:

Red dragonfly on my shoulder,
Calls me his friend.
Autumn has arrived.

I’ve often had them “on my shoulder,” but last autumn I had them covering my entire body – literally from head to toe.  Here’s what happened.

I went to Cranberry Lake on November 9, 2011 to observe the dragonfly activity.  The weather was sunny and calm, with an air temperature of 57 ˚F.  On other similar days I would observe about a dozen Autumn Meadowhawks and half a dozen Shadow Darners.  On this day, however, I immediately realized something was different – there were so many Autumn Meadowhawks on the gravel walking path that I had to choose my steps carefully to keep from stepping on them.

I walked to some bushes near the shore to see if any darners were perched there, but as soon as I stood still for a moment the meadowhawks began to gather on me.  It felt like a scene from Hitchcock’s movie, The Birds.  They were landing all over me in a frenzy.  I took some pictures showing the ones perched from my waist down, but as I took those pictures I could feel them perched on my arms, my upper body, my head, even on my face.  The pictures show over 30 on my lower body, and I would estimate there were 50 or more on my body as a whole.  I’ve had several Autumn Meadowhawks land on me before, but never anything like this.  

A gathering of Autumn Meadowhawks at Cranberry Lake in Anacortes, Washington on November 9, 2011.

The ones pictured on my lower body are only half the story – they covered me from head to toe.  It felt like a scene out of The Birds.

After taking a few pictures I looked up and saw that the air was just “full” of meadowhawks flying in all directions, hooking up in tandem or attempting to hook up.  It was similar to a mass flight of winged ants or termites.  A few darners were flying too, picking off individual meadowhawks, and also pairs in tandem, and heading for the bushes or trees to enjoy their catch.  It was quite a scene.  It’s hard to estimate the number of meadowhawks, but it must have been in the several hundreds.

I decided to go home and bring Betsy to see this phenomenon.  As I walked back to the car the meadowhawks went along for the ride on my body.  The car was a considerable distance away, and in the shade, but there were still a dozen or more dragonflies on me when I got there.  I had to “shoo” them away to keep them from getting in the car with me – though one managed to do so anyway.

When Betsy and I returned a few minutes later, the activity level was a bit lower, though still intense.  We marveled at the meadowhawks that seemed to be everywhere we looked, including all over us.  Along the shore we observed an egg-laying frenzy, with intense competition for prime sites.  As a result of the competition, many meadowhawks were being knocked into the water where they became stuck.  We ended up rescuing a dozen or more.

As we watched the egg-laying activity, the shadows of the afternoon (it was about 2:00 pm at this point) began to lengthen.  We expected to see the meadowhawks moving along the shore to stay in the sunlit areas, but at one point – quite suddenly – we noticed that the egg laying had ceased, and the air was now clear of meadowhawks.  It was almost as if someone had flipped a switch.  We’re not sure what the signal for stopping was – it wasn’t evident to us – but the meadowhawks seemed to respond en masse.

We returned the next several days, but each time the activity was completely normal again, with just a dozen or so meadowhawks along the shore.  The mass behavior seen on November 9 was a short-lived phenomenon, but one we’re happy to have experienced.

Sunday, February 26, 2012

A Four-Star Teneral

A teneral is a dragonfly (or other insect) that has just undergone moulting.  In photo below, a dragonfly has just emerged from its last larval stage to become a winged adult.  It has given up the underwater existence it's known all its life to become an air-breathing, flying adult.  It doesn't moult again.

The teneral pictured above is a male Western Pondhawk.  You can tell it's a male by the presence of hamules, the bumpy structure that projects downward near the base of the abdomen.  The hamules are used to "latch" the male and female together during mating in the wheel position.  In a female, the underside of the abdomen near the base is smooth.  

It's always important to know which sex you're looking at when identifying dragonflies, but with this species it's particularly helpful because both sexes start off brilliant green.  Female pondhawks stay green as they mature, but the males turn from green to blue in stages starting at the tip of the abdomen and progressing toward the head.  The body and eyes of the adult male are solid blue, only the face remains green – in fact, the green face is a good distinguishing feature to separate male Western Pondhawks from male Blue Dashers, which have a white face.

Tenerals have a "fresh" look to them, with distinctively vivid colors.  The wings of a teneral look almost like cellophane.  In fact, the wings haven't completely hardened at this stage of a dragonfly's life, and as a result the flight of tenerals is usually quite weak and slow – almost like the fluttering flight of winged termites.  In fact, it's often possible to recognize a teneral from some distance because of its characteristic flight behavior.  When a dragonfly is fully mature, however, its flight becomes strong and fast, as you would expect for a top predator.

Saturday, February 25, 2012

Blue-eyed Darner

A beautiful, male Blue-eyed Darner rests on my finger at Cranberry Lake.  The brilliant blue eyes are a particularly striking feature of this species.  This is a "textbook" view of the Blue-eyed Darner, and though it shows the beauty of the animal, it misses the interesting appearance of its face.

Here's a head-on view of the Blue-eyed Darner.  Notice the two prominent primary pseudopupils that seem to be looking right at us.  This species lacks the heavy "eyebrows" and dark "smile line" of the Paddle-tailed Darner (Happy-face), but it still has a nice expression.  The side view above gives no hint of what this dragonfly looks like when viewed from the front.

An Unusual Blue-eyed Darner

A male Blue-eyed Darner (note the narrow waist on segment 3) perches in the bushes at Cranberry Lake, in Anacortes, WA.  This is an older individual, as evidenced by the scuffed up wings and the ragged trailing edge of its left hindwing.  From this distance it's clear that something is odd about its right eye, which seems to have a dark spot on it.  I came in closer to get a better look.

Now it's clear that the dark spot is actually something that projects out from the eye.

A closer look shows that the dark spot has the same hexagonal grid as in the eye itself.  Apparently it resulted from some abnormality in the growth of the eye.

I lifted the dragonfly onto my finger for a better look.  The dark spot is on the upper edge of the dorsal fovea, which extends down to a point just behind the primary pseudopupil.  The secondary pseudopupils form a nice hexagonal lattice, as one would expect.

Friday, February 17, 2012

The Happy-face Dragonfly

This is the first picture I took of a Happy-face Dragonfly.  When I took the picture, on October 22, 2006, I had no idea its face looked like this – it wasn't until I got home and viewed the picture on the computer that I realized what I had discovered.  This picture is what really "hooked" me on dragonflies.

The official common name of this dragonfly is the Paddle-tailed Darner.

How Slow Is Slow?

This is a video of me juggling on our deck.  The first part is regular speed, 30 frames per second (fps); the second part is 1/8th speed, 240 fps.  The 1/8th speed is what I use for slow-motion dragonfly videos.  It's good to keep this in mind, because it's easy to watch the dragonfly videos and think of them as being regular speed.  It should always be remembered that we're seeing the dragonflies at speeds that make a person look like a sloth.

Saturday, February 11, 2012

The da Vinci Code

In Leonardo da Vinci's notebooks on flight he considered many different flying animals – birds of course, but also a moth, a flying fish, and a dragonfly.  (Actually, Dennis Paulson notes that the fish shown on this manuscript page is a gurnard, a fish that never leaves the water.  Still, it has incredible pectoral fins.  Thanks, Dennis!)

Sunday, February 5, 2012

Crossed 3D Photos

The three photos in this post are crossed 3D pictures taken with a 3D camera that uses two lenses instead of just one.  The two lenses give a slightly different perspective on the scene, just as our two eyes see everything a bit differently.  When the brain combines the two images a very nice 3D sensation is produced.

As I mentioned, these photos are "crossed 3D."  What this means is that the proper viewing technique is for the right eye to view the left image and the left eye to view the right image.  To accomplish this, first pretend to be looking at something just in front of your nose.  As you do so each image will double.  In the middle the images overlap.  By making them overlap perfectly, and keeping them overlapped as you adjust your focus, you can view the 3D effect.

The first photo is on my deck, looking out toward Burrows Island in Puget Sound.  The small spot just above and to the right of center is a Paddle-tailed Darner (Mr. Happy-Face).

Betsy on the south rim of the Grand Canyon.

Our lunch spot at the Boyce Thompson Arboretum, near Mesa, AZ.  We've hiked on the hillside in the background many times.  In the spring of 2011 a wildfire burned on the hill right down to the trail.  Fortunately, it didn't cross the trail or enter the main grounds of the Arboretum.

Thursday, February 2, 2012

The Unexpected Pleasures of Dragonflying

One of the great things about dragonflying is that it gets you out into some beautiful wild areas where you never know what you'll find.  On one of our dragonflying trips we saw this beautiful Eastern Collared Lizard (Crotaphytus collaris baileyi) on a rocky outcrop near the road.  This was a large lizard – the largest and most colorful I've ever seen in Arizona.  The intense electric blue of its body was dazzling in the sunlight, and the yellow "booties" on its feet provided a striking contrast.  What an incredible lizard.  To get a feeling for its size, the loose rock just below its head is about the size of a person's hand.

We saw this lizard near one of our favorite dragonflying locations on Tortilla Creek, right where it crosses the road in the little "town" of Tortilla Flat.  We see lots of interesting dragonflies there, including the Giant Darner, Widow Skimmer, Black Setwing, and Plateau Dragonlet.