Four-spot Capture

One of the slow-motion videos I took this summer showed a Four-spotted Skimmer chasing and catching a small fly.  The way he did it was a bit surprising, though.  He waited until the fly passed him, turned and flew ahead of the fly, and then approached it head-on for the capture.  Here are some frames from the video that document the event.

In this frame, we see the small fly (red dot) ahead and to the right of the skimmer.  A blue dotted line goes from the head of the dragonfly to the prey.  The fly is traveling in a straight line at uniform speed – apparently oblivious to the potential danger in its vicinity.

In this frame the dragonfly is basically in its same position, soaring motionless in a headwind, as the fly gets closer.

Here the fly is passing the dragonfly, while the dragonfly continues to hold its position.

As the fly continues on its path, past the position of the soaring predator, the dragonfly suddenly initiates a turn to go toward the potential prey.

Now you might think the dragonfly would overtake its prey from behind and make the capture that way, but instead it zips ahead of the prey and turns to face it, as we see in this frame.

The dragonfly now drops below the prey, and puts itself in a position to rise and capture the prey head-on, which it does just a split second after this frame.

Of course, in real time this happened so quickly that no details could be made out.  I knew a capture had occurred, but that was about all.  Fortunately, the slow-motion video allowed for a detailed look at just how the dragonfly effected its capture.  Cool!

Cap Sante Hilltopping

In my hometown of Anacortes, there's a nice park on a hill called Cap Sante.  Looking to the west from the summit of Cap Sante you get a great view of downtown Anacortes and the Cap Sante marina, as shown below.  The marina services both pleasure boats and commercial fishing boats, many of which fish for crabs and salmon in Alaska.

Downtown Anacortes as seen from Cap Sante.

Cap Sante is also a great location for watching sunsets:

Sunset from Cap Sante, in Anacortes, WA.

In addition, if you look to the east from Cap Sante, you get a magnificent view of Mount Baker, a 10,781 ft high volcano in the Cascade Mountain range.  Here's Mount Baker as seen from Cap Sante:

Mount Baker in the North Cascades, as seen from Cap Sante Park in Anacortes, WA.

What does Cap Sante and its wonderful views have to do with dragonflies?  Well, Cap Sante is a good place to observe hilltopping – a behavior where a group of dragonflies (or other insects) gather in considerable numbers above a prominent feature in the landscape.  In some cases, hilltopping is said to be a reproductive behavior – a way for insects to find mates.  In the case of the dragonflies at Cap Sante, it appears to be a gathering of immature individuals who are feeding together in a loose swarm.

The dragonflies at Cap Sante are mosaic darners, and they are clearly feeding as they fly back and forth over the top of the hill.  The darners really don't interact with one another – they seem focussed on feeding and maturing, before going back to a lake or pond to find a mate.

Here's a compilation of some slow-motion videos showing darners hilltopping over Cap Sante with Mount Baker in the background.  The dragonflies fly and soar almost like hawks.  Notice the interesting flight maneuver at about 18 s, where a darner snags a meal.

Forktail Interaction

Western Forktails differ from many other damselflies in an interesting way.

If you go to a nice pond in the summer in Washington state, you are quite likely to see female Western Forktails.  They are pruinose blue overall, and quite easy to spot as they move along the shore laying eggs in one location and then another.  You don't see male Western Forktails, however.  It can be quite tough to spot a male.  What's going on?

Apparently, most female Western Forktails mate just once in their lives; after that they fend off other males who attempt to mate with them. A good example is shown in the slow-motion video below.  The video starts with a female Western Forktail minding her own business.  Suddenly a male races in to grab her and attempt to mate – not really much in the way or courtship, I'd say.  The female resists, and eventually the male moves on.  After getting this kind of treatment from the females, the males apparently move off into the bushes to forage and thus are not encountered very often.

According to Dennis Paulson in Dragonflies and Damselflies of the West, female Western Forktails are "very effective at repelling attention of male forktails and bluets by fluttering wings and curling abdomen tip down."  Here's a good example of that.

Splash-Dunk (x2) + Spin-Dry Video

Here's one of my favorite splash-dunk/spin-dry videos.  It was taken at Cranberry Lake in Anacortes, WA.

The dragonfly in this video, most probably a male Paddle-tailed Darner, makes two nice splash-dunks.  It then takes a long, smooth glide toward the water as if it might dunk again.  At the last moment it changes its mind (apparently) and decides to head upward for a spin-dry.  The resulting spin sheds a large number of water droplets.

Check out the post "How Slow Is Slow" to get a feeling for how slowed down this video really is.
http://thedragonflywhisperer.blogspot.com/2012/02/how-slow-is-slow.html

Also, recall the following overview that gives a good idea of what's going on in splash-dunk/spin-dry behavior:

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.