Sunday, November 11, 2018

Cool Dragonflies

Well, we're nearing the end of dragonfly season. The days are getting shorter and colder, but there are still a few dragonflies out there. Yesterday, Betsy and I went to Little Cranberry Lake here in Anacortes to check out the action, and we saw quite a bit. Here's the lakeshore:

The temperature was 44 ˚F the entire time we were there, which was approximately from noon to 1:00 pm.

First, we saw quite a few Autumn Meadowhawks; mostly males, but a few females as well. We didn't see any egg laying activity, however.  Here are a few male Autumn Meadowhawks sitting on the bench near the shore:

This is a great place for them to bask in the sun. On the fence nearby a pair was in the wheel position:

Here are a couple males that at first glance appear to be in tandem, but in fact are just resting in close proximity:

Here's another male resting in the bushes just back from the shore:

We also saw darners, both Paddle-tailed Darners (Mr. Happy Face) and Shadow Darners. Here's a male Paddle-tailed Darner perched in the bushes:

For a size comparison, notice the small housefly at the 10 o'clock position.

Here's a close up of this individual, showing the happy face:

It's always wonderful to see this in person.

Finally, here's a female Shadow Darner:

A close-up look shows a bit of a happy face for her as well:

What a lovely November day at the lake.

Thursday, November 8, 2018

Wingbeat Phasing in Cardinal Meadowhawks

Here's an expanded version of this earlier post. In this new version, I include screenshots showing the various stages of a wingbeat cycle:

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 ready to lay one or more eggs. They then dip down and drop off the eggs. The wingbeat frequency during this process is approximately 48 beats per second—that is, five frames at 240 frames per second.

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 with one another, 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 and Autumn Meadowhawks. It will be interesting to see how widespread this behavior is among other species.

For a bit more detail, let's take a look at frame-by-frame screenshots for a typical cycle:

Here's frame 1 of the cycle. In this frame, the female's hindwings are up.

Next, frame 2 (recall that the frames are taken at 240 frames per second).

Frame 3 shows the female's forewings and male's hindwings in the up position.

Frame 4 shows the male's forewings up.

Frame 5 ends the cycle.

Frame 6 starts the next cycle, with the female's hindwings up again.

Very interesting phasing between the male and the female.

Monday, November 5, 2018

Species Spotlight: Emma's Dancer

In the spotlight today is a beautifully-colored damselfly—Emma's Dancer. As with other dancers, this damselfly holds its wing above the abdomen when perched. In addition, it has a lovely lavender color on the thorax. Most of the abdomen is also lavender, with a contrasting blue tip.

Here's a male from Lower Crab Creek near Beverly, WA on the Columbia River:

Before finding this species at Lower Crab Creek, we had seen it only a couple times before near Bend, OR; in those cases, however, we generally saw just a single individual. At Crab Creek, they were the most numerous damselfly.

Here's another male, with a bit different lighting showing off the lavender color:

A final male, with even different lighting. It shows the range of colors observed in this species:

We saw lots of females at Crab Creek as well. Here's a male and female in tandem preparing to lay eggs:

Here's a close up of the female. Notice her light brown color, and light stigmas. In addition, the ovipositor is clearly visible at the tip of the abdomen—all damselflies use ovipositors, but many dragonflies use an egg scoop instead, and just drop their eggs in the water.

The next female has her hindwings spread open, and her abdomen bent, as she fends off the advances of a male:

One final look at the female, showing her wings held well above the abdomen:

This is a species that can be locally numerous, but is not particularly widespread.

Monday, October 29, 2018

Aging in the Eight-spotted Skimmer

Dragonflies lead active lives, and as a result, they show clear signs of aging. Here are some photos showing the progression of aging in Eight-spotted Skimmers.

First, we see a fresh, clean young male. Notice the sheen on the sparkling-clean wings, and the nice clean body. Also, we see that the pruinosity (or pluminosity if you like) is not yet fully developed, and the yellow side stripes seen in young males are still visible. A beautiful individual in the prime of its live.

Next, we see a middle-aged individual. The pruinosity is fully developed here, and a dark patch is seen in the middle of the abdomen where pruinosity has been rubbed off by females grasping the abdomen at that location during mating. The wings are nice and brilliant, though not quite as "new" looking as in the previous individual.

Finally, we take a look at an individual that is clearly showing the effects of age. The wings are tattered now, with sections missing here and there. The abdomen is faded, though the dark section in the middle of the abdomen can still be seen.

It's amazing that this individual can still function with wings like that, but it was seen flying about seemingly unaffected by the wear and tear.

Friday, October 26, 2018

Sun Mountain Meadowhawks

A few years ago, Betsy and I spent a few days at the Sun Mountain Lodge in Winthrop, WA to enjoy the wonderful Fall colors. That visit was incredible also because of the six different species of meadowhawks we saw.  Here's our report from October 23 and 24, 2013:

Last week, October 23 and 24, Betsy and I went to the Sun Mountain Lodge in Winthrop, WA to enjoy the Fall colors for a couple days.  It was beautiful there, as you can see in these photos:

Sun Mountain Lodge from our room.
The Fall colors were in full effect.
A Golden-crowned Kinglet gave me an opportunity for a quick snapshot.

We went to the Beaver Pond, of course, but weren't expecting that much dragonfly activity.  We would have been happy to see a few.  As it turned out, the activity was very good, with lots of darners patrolling the shore looking for females, and meadowhawks flying in tandem over the water, dipping and laying eggs.  In some areas, each step would flush several meadowhawks from the ground into the air.  It was delightful.  We had a six meadowhawk day, with the following species:

White-faced Meadowhawk
Striped Meadowhawk
Saffron-winged Meadowhawk
Band-winged Meadowhawk
Black Meadowhawk
Autumn Meadowhawk

A six meadow hawk day would be good in the summer, but was especially pleasant to experience this time of year.  The most common species was the Saffron-winged Meadowhawk.  We saw only one White-faced Meadowhawk, and it set a new record late date by 16 days.  Here are pics of the meadowhawks:

White-faced Meadowhawk.
Striped Meadowhawk.  An older individual with frayed wings and faded stripes.
Saffron-winged Meadowhawk on the left, and Band-winged Meadowhawk on the right.
Black Meadowhawk.  We don't see Black Meadowhawks all that often, so this one was a particular treat.
Autumn Meadowhawk.  One of the "field marks" for Autumn Meadowhawks is that they land on you.

As usual, we had a great time at the Sun Mountain Lodge and the Beaver Pond.

Wednesday, October 24, 2018

Species Spotlight: Easter Amberwing

In Arizona, we often see Mexican Amberwings. These are small, orangish dragonflies that probably gain some protection from predation by looking and acting like wasps. On the east coast, we see another species of amberwing—the Eastern Amberwing. It looks much the same as the Mexican Amberwing, and has similar habits.

We saw several Eastern Amberwings on our trip back east this spring. Here's a male that we saw at our hotel near Boston, MA:

Notice the orangish (waspish) color, and the body that is rather short and stocky for a dragonfly. Notice also the light spot on the side of the thorax.

Male amberwings patrol their territory, looking for suitable egg-laying locations. After mating with a female, males lead her to the chosen egg-laying site, where the males dip—as if they were laying eggs—to induce the female to lay eggs. The female may or may not find the site suitable; if she does, she will begin to lay eggs there.

Here's the female Eastern Amberwing:

Notice the darker, less prominent color of the female, the light spot on the side of the thorax, and the splotchy spots in the wings. Females perch away from the water, where they blend into the vegetation, until they are ready to lay eggs.

P. S. My field guide, Common Dragonflies and Damselflies of the Pacific Coast, has been hard for Amazon to keep in stock—it keeps selling out faster than they can get new books in the inventory. It's back in stock now, and is available for a particularly good price, at the following link:

Field Guide

Friday, October 19, 2018

Mount Baker

We went to Mount Baker yesterday. It was lovely, with temperatures in the mid 60s, beautiful scenery, and some fun birds and dragonflies. First, here's the view at Picture Lake, with Mount Shuksan (just over 9,000 ft in elevation) in the background:

Here's Mount Baker, with Betsy on the trail:

In this area we saw some Pine Siskins and Bohemian Waxwings. Here are a couple views of them:

Bohemian Waxwing (left), and Pine Siskin (right).

Notice the yellow tips on the primaries, and the two white splotches on the side of the wings. I was surprised to see Bohemian Waxwings, as opposed to Cedar Waxwings, and so was eBird—I had to file a rare species form for this sighting.

We also saw some darners, including one that did a series of three splash-dunks followed by a nicely visible spin-dry. We saw a couple different species flying by, but only one landed for us—a Paddle-tailed Darner (Mr. Happy-face).

What a beautiful day.