Monday, September 21, 2009

Autumn Meadowhawks

Yesterday was the last day of summer. This string of endless sunny days has been a phenomenal opportunity to go out and watch animals that love the sun. For us, right now, that means dragonflies.

So my friend Jay and I went out to McLane Creek beaver pond once again. We decided to go out a little earlier this time; females and males use the pond differently at different times of day, and we wanted to see if we could observe these shifts in the daily use of the beaver pond.

When we got to McLane around 1:00 pm, it was about 60 degrees, and the sun was shining fully on the pond. It was very quiet, dragonfly-wise. We watched a few drab-colored female dragonflies whisking around the surface of the pond, occasionally dipping their abdomens into the water, most likely dropping off eggs. From my reading, female dragonflies tend to avoid the ponds (and the herds of sexually eager males), so those that are ready to lay eggs (oviposition) show up early and later in the day, when the males are less likely to be around.

As the afternoon warmed up, we started to see Shadow Darners (see previous blog) and Jay made a skilled swing with her net and caught one. Here is a photo of her gently extracting him from the green net bag, holding two wings on one side to prevent his escape. We took a few quick pictures, then let him go on his way, watching as he seemed to shake off the indignity of capture, then return to his previous circuit of the pond.

Around 2:00 pm we were surprised when several tandem pairs of red Autumn Meadowhawk dragonflies started to appear. In reading Dennis Paulson's book on Dragonflies of the West, it appears that when some Meadowhawks are ready to mate, they "hook up" with their partners near their night roost sites in the woods, then fly in tandem to the ponds, where the male flies the female low over the water, where she then curves her abdomen down and deposits her eggs.

The male has a special pair of claspers at the end of his abdomen, which are readily seen in this photo. When he makes hopeful ventures to a possible perched female, he is said to flutter and do a kind of courtship dance. If she is duly impressed, she cooperates, by allowing him to hook his claspers on her prothorax, a kind of narrow neck area behind her eyes ( it gives a whole new meaning to the phrase "hooked up"). This is called the tandem position.

If she is willing to mate, she then curves her abdomen up and touches the tip to the second segment of his abdomen, which is the genital bump. He then transfers sperm to her to fertilize her eggs. This is called the wheel position. They may then return to the tandem position, where he flies her to the pond to lay eggs, ensuring that HIS sperm are the ones that fertilize her eggs.

We saw many pairs in tandem, and watched a few hovering over the pond, no doubt laying eggs. It was amazing to see. Even though we were not able to net many dragonflies that day, we saw a lot of interesting dragonfly behavior that was new to us. For nature watchers, this is nirvana.

As the afternoon wore on, we saw more male Autumn Meadowhawks, by themselves. There was a lot of basking going on (perhaps post-coital). They were sunning themselves on the railing of the dock, on nearby cattails, even on my knee, briefly. September is late for dragonflies to be out and mating. I have read that the Meadowhawks who flourish in northern climes do so in part by spending a lot of time basking in the available sun. We certainly saw signs of that on this field trip.

By 3:30, activity was slowing down a great deal, and it was time for us to head home. That night my sleep was deep, drugged as I was with hours of sun and fresh air. Through my dreams, red dragonflies danced and wheeled in the last sunny hours of summer.


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