Monday, January 30, 2012

The Rest of the Story




A picture is worth a thousand words, as the saying goes, but that doesn’t mean that there aren’t many more words lurking behind the photo which tell a much more interesting story.

What do you see in the photo above? The primary subject is a dragonfly—a female Grappletail (Octogomphus specularis) to be exact, a species of clubtail in the family Gomphidae. What is the slender blue “stick” that this Grappletail is grappling? That is the abdomen of a male Vivid Dancer (Argia vivida)—a damselfly, his head and thorax in the dragonfly’s digestive tract by the time this photo was exposed. Odonate-on-odonate predation is always interesting when you see it, but not so uncommon that it’s ever a surprise—especially in cases like this when the predator is significantly bigger than the prey.

That photo was taken at Gold Lake in the central Oregon Cascades—a special place for a number of reasons. One of them is the large numbers of Grappletails that congregate where the waters flow out of the lake and become Salt Creek. Dozens and dozens of them can be seen sitting all over the place—on boulders, on logs, on the bridge over the creek, on the surrounding vegetation, and on you. I have photos of up to 13 of them perching on a single boulder. It is really odd to see so many individuals of any clubtail (or any dragonfly species, for that matter) together at one place. It’s also a very enjoyable place for photography since there is at least one Grappletail everywhere you look, and they are often very approachable.

Here's a better view of a different female Grappletail (Octogomphus specularis) at Gold Lake.
 
During a Gold Lake visit in August of 2007, I was trying to photograph a female Grappletail that was sitting on a log, but as I was looking through my camera’s view finder, a blue blur kept buzzing her head and she flew up each time to chase the annoying meddler away. This wasn’t working out for me, so I lowered my camera to see what was going on. The intruder was a damselfly—a male Vivid Dancer (Argia vivida). What was he doing? Well, I couldn’t be positive, but it sure looked to me like the little guy was trying to go into tandem with the relatively gargantuan Grappletail (with the ultimate goal of copulating, presumably). I guess he had a fondness for Amazons.

I know, I know, this seems pretty fantastic, but each time the damsel dropped down, he curved his abdomen forward as though he intended to clasp her behind the head with his abdominal appendages. I can’t imagine what else could have possibly motivated him to do such a thing. The mere notion that a damselfly would even attempt to go into tandem with a dragonfly—one twice his length, really blows my mind. It’s unheard of as far as I know. Assuming that I correctly assessed the dancer’s intentions (I concede that I could be wrong, but I can’t imagine what else was going on), it raises some interesting questions such as, Can a damselfly really know whether a dragonfly is a male or female, and if so, how?

An intact male Vivid Dancer (Argia vivida) wisely
copulating with a female of his own size.

It’s funny to think about what it would have looked like if he was successful, if she was receptive, and they actually got tab A into slot B. Take a look at the copulating pair of Vivid Dancers at right, and just try to imagine that the female (the non-blue one) is a dragonfly about twice as long as the male and quite a bit chunkier. Completing that circle would put some serious stresses on the joints!

Naturally, the Grappletail was having none of it! She chased the little dancer away four or five times, returning to her log after each flight. Unfortunately for him, he made one too many attempts. The last time he dropped down, she flew up, chased him, grabbed him in mid-air, and perched in streamside trees to make a meal of the little love-struck damsel. That was when I snapped the photo at top, and that’s the rest of the story.

9 comments:

  1. A few years ago in Baxter State Park in Maine in the fall, we came across a couple of large dragonflies in the middle of the road. I stopped and got out to look closer and was shocked to see that one was grasping the other and it took off and flew away with it-- not mating style, predator style. The one was almost as big as the other! I don't recall now what kind it was but probably not a lot of kinds of dragonflies can do that!

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    1. Sometimes odonates will prey on other species that are almost as big as them, but you don't see that too often. Always cool to see.

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  2. Jim, are you playing Paul Harvey? This is very interesting. Have you shared this with your circle of odonatologists? I wonder if there are any other explanations for this obviously unsuccessful behavior. Did I ever send you the link of andromorph female damselflies in HI?

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    1. Hi Katie. I may have been channeling Paul Harvey a little bit! I wrote a note about this for the Dragonfly Society of Americas newsletter a few years ago, so it's actually recycled news (with a different presentation). There may be some other explanation, but I just can't imagine what that might be.

      No, I didn't get a link from you...

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  3. Oop, I think I know why I didn't send the link. If you look past the flirty fluff, the research being done by grad student Eben Gering (U of TX) is interesting: http://carinbondar.com/2011/01/biomusings-episode-4-celebration-of-the-female-form/

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    1. Thanks! It's nice to hear that someone is actively researching that. Andromorphs (I prefer the terms androchrome/gynochrome since it really is a color difference instead of a morphological difference, but "morphs" are in common usage) are found in most damselflies and in certain dragonflies like the darners. I've been thinking about writing about this topic. Maybe I'll do that next...

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  4. Looking forward to your next topic. I really do like your blog. It's very accessible for those of us not fanatical about Odonata.

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