Dragonfly Monitoring Run

by Carl Strang

On the 4th of July I made my first dragonfly monitoring run of the year, on my assigned stretch of the Des Plaines River at Waterfall Glen Forest Preserve. With a total of 378 individual dragonflies and damselflies tallied, it was far higher than any other count since I took this route beginning in2009. Of course, there was a lot more to enjoy than just Odonata.

A string of great blue heron nests between the boat launch and the start of my route still had some youngsters approaching fledging. Their loud rhythmic guttural calls signaled the arrival of a parent, back from fishing the river.

The carp fence I saw under construction when I last paddled the Des Plaines in the fall is complete. Am I being ignorant or properly skeptical in doubting this will achieve the desired result of keeping Asian carp from moving between waterways?

My thinking, for what it’s worth, is that even if the mesh is fine enough to block tiny youngsters that might slip through at flood stage, there will be breaches from floating logs.

Later, when my run was nearly complete, I encountered this northern water snake.

I was surprised that it seemed undisturbed by my close approach. Then I saw that the eyes were obscured. The snake either was on the verge of shedding, or the scales over the eyes remained stuck when the rest of the skin came off during the last shed.

Entertaining as these sideshows were, dragonflies and damselflies were the main event. Jade clubtails were the most abundant of the 5 species of dragonflies that day; I counted 46 altogether.

Jade clubtails mainly are to be seen perched on objects like this stump.

Common whitetails also were regular sights, some laying eggs.

Here a male common whitetail shares a stump with a bluet and a clubtail.

Most of the individuals were damselflies, however, in 8 species. The largest were a few American rubyspots.

This one was so steadfast that I was able to bring the camera to within a few inches of it.

The largest count of any species was 108 blue-tipped dancers. I didn’t get a photo of any of them, but one of the 82 powdered dancers, a close relative, posed on my deck line.

Such accommodating individuals make identification easy.

The most abundant bluets this time were stream bluets.

The stream bluet is one of the black-type bluets, having a mainly black abdomen.

Stream bluets and hordes of dancers were laying eggs in floating vegetation mats.

The several tandem pairs, perched on the vegetation and laying, may not be as visible here as the unattached and hopeful males hovering above.

I had thought I might do a little fishing on the way back, but the time and mental effort required to identify and count so many insects left me glad simply to paddle back up to the put-in.

October Monitoring Run

by Carl Strang

Last weekend’s warm weather allowed me to make a late dragonfly monitoring run on the Des Plaines River at Waterfall Glen Forest Preserve. Looking back through my records, I find that in all the monitoring I have done since 2003, I never have made a formal outing in October. It was worth trying for that reason, if no other. Besides, it was a nice day to be on the river in my sea kayak. There isn’t a lot to report as far as dragonflies and damselflies go. The only dragonflies were a pair of common whitetails, the female laying some last ditch eggs. I saw a couple familiar bluets,

a few orange bluets,

a stream bluet, 3 eastern forktails and 7 American rubyspots.

The last confirmed that this species is active late in the season, supporting my sighting at Fullersburg (which at first I thought was a smoky rubyspot). I also made some singing insect observations, the best of which were jumping bush crickets singing in the early afternoon on both sides of the river. This adds to my local range for this species, which clearly has shifted north of where you will find it mapped in references. The shallow lagoon at the downstream end of my monitoring area was hosting a gathering of great egrets.

The gorilla in the room, however, was a major construction project underway on the south side of the river. A fence was being built.

With much machinery, much shouting and an impressively speedy progress (I saw no sign of this when I last was there in late August), a metal framework is being erected and filled with fine-meshed screening.

The fence is parallel to the Centennial Trail, which has been closed for this project. The fence is only 6 feet tall or so, enough to disrupt the view of trail users but not enough to be a significant barricade to wildlife, I thought. A little research on the Internet revealed the purpose of this structure. It is a fish barrier. That may seem strange, but high water levels could lift the river high enough to reach the fence. The target fish are Asian carp, a group of 4 species which have been much in the news because of concerns that they might cross from the Mississippi River drainage (which includes the Des Plaines) and the Great Lakes. The Des Plaines River is paralleled by a canal, so the fence apparently is intended to keep the carp from going between the two. Would tiny baby carp be stopped, though? I’m not enough of a fisheries biologist to judge. For more information on the fish species and other information, here is a link.

Kayak at Last

by Carl Strang

I was beginning to wonder if I would get the opportunity to put a paddle in the water this year, but circumstances allowed me to run my dragonfly monitoring route on the Des Plaines River at Waterfall Glen Forest Preserve this past weekend. Of course, in the context of this blog the monitoring is the main thing, but on a personal level it’s been hard to go almost a year without paddling. My sea kayak has taken me through north Georgian Bay.

It’s given me sights like this, Devil’s Island in the Apostles of Lake Superior.

On Sunday afternoon the sea kayak Water Strider was my vehicle yet again. I found no new species, but was interested to find that the counts for various species fell between the values for last year’s August 2 and September 3 counts, despite other measures of phenology generally placing this year earlier than last. Common whitetail and eastern amberwing dragonflies were closer to the August 2 count, though both exceeded any of last year’s counts for those species. Powdered dancers and stream bluets fell between the counts of last year’s dates. Familiar bluets were closer to the September 3 count. Many, like those in the following photo, were ovipositing.

Skimming bluets showed a significant increase, with 10 counted on this trip against 1 for the entire 2009 season. In contrast, jade clubtails were missing this time, and orange bluets were few. I wonder if their seasons are done for this year.

Dragonfly Monitoring Update

by Carl Strang

Earlier I described  my first venture into dragonfly and damselfly monitoring by kayak. I have been out on the Des Plaines River twice since then. There has been some variation in the count of species and individuals each time, but most seems unremarkable. I’ll focus on a couple high points. The biggest surprise was a transition in the damselflies. The slender bluet was the common black type bluet my first time around.

Slender bluet 5JL 1b

Bluets are a group of small to medium sized damselflies. Black type bluets are so called because their abdomens are nearly all black as viewed from above. On my second and third outings, the slender bluets were replaced by stream bluets as the common black type bluets. Here is one of the latter I rescued from the water.

Stream bluet 23JL09 1b

Note that, in contrast to the slender bluet in the top photo, the stream bluet has a slender blue shoulder stripe with a wider black stripe below it. “Eye spots” on the back of the head are smaller in the stream bluet, and there is less blue in the abdomen tip. Stream bluets were largely in tandem pairs and actively laying eggs on floating vegetation during both recent outings.

Stream bluets tandem b

The other surprise is the relatively large number of orange bluets. Here is one sharing a photo with a stream bluet.

Orange and stream bluet b

I’m not saying that the river is swarming with them, but in my experience a count of 13 orange bluets in a 2-hour outing is a lot. A final note is that eastern amberwings have become the most abundant dragonflies, despite my seeing none on the first outing. Here is a photo of one from 2007.

Eastern amberwing male 2b

I have decided to limit my monitoring to the stretch of river that bounds Waterfall Glen Forest Preserve. This gives me a span of stream between the launch ramp and the preserve in which I can practice another type of inquiry, to be featured tomorrow.

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