Monday, May 28, 2012

One Darner of a Day

Yesterday, on May 27, I drove over to the SW corner of Washtenaw County to see what was flying at the Nan Weston Preserve in Sharon Hollow. It's been on my watch list for some time due to the fen that is there along with the shallow streams fed by seeps. A few years ago I found Cordulegaster maculata and C. obliqua on the same day in late May. However, this latest visit was mostly to see if there is any possibility that it could be a site for Tachopteryx thoreyi. I have often wondered if it was possible that there might be small numbers of the Gray Petaltails where we have seeps and and fens in SE Michigan, and Sharon Hollow certainly has some good habitat. After looking around in the area for several seasons, I guess I am now convinced that if it was there, I would definitely have seen one. However, yesterday's trip was made special by the presence of Spatterdock Darners, Rhionaeschna mutata! They were everywhere, and I have never seen so many at one time. Both sexes were flying along the edge of the woods where the powerline right-of-way cuts through the preserve. Some of them were recently emerged, but most of the males were quite mature, with those beautiful sky-blue eyes.
Spatterdock darners are reputed to thrive in fishless ponds, or at least where fish large enough to prey on them are missing. My guess is that some of the many that I was seeing came from the mucky pond that is at the edge of the powerline, and is fed by the fen that's there. Lots of skunk cabbage grows along the margins, but it never dries out. In previous years I have seen a few R. mutata at the site, but never like the numbers that I saw yesterday. I lost count, but it was over several dozen at the margins of the powerline cut. Spatterdock darners typically perch (actually, they hang) from branches or tree trunks while they are maturing, and I think that's when they are most often photographed.

This female is not yet fully mature, as can be seen by the dark eyes and muted colors. I have also seen R. mutata take cover on trees on shrubs when it has started to rain, as well as a sort of siesta when it has been hot and sunny. Mostly though, one sees them "perch" when they are still maturing. The wings have a slight amber tinge at that stage as well.

After I was finished at the Nan Weston Preserve, I decided to continue down Easudes Road into Jackson County and collected in the Sharonville State Wildlife Management Area (you can always tell when you are in a State Game Area, because so many morons think signs are wildlife). As I crossed one four-corners, I saw dozens more R. mutata flying in the roadway in what appeared to be feeding swarms. In one opening at the edge of a field I saw dozens more feeding, and some were perched on shrubs. One perched male looked like he had emerged within a few hours. As I drove along towards Tamarack Lake, I saw more darners flying along the road. I parked at the Tamarack Lake site, and took the trail down to the lake. In the field edges, I saw more R. mutata. This has to have been an epic emergence of Spatterdock darners. I also saw a bunch of Libellula cyanea at Tamarack Lake -- a very pretty skimmer with black and white stigmas. Spangled skimmers are not everywhere, but mucky-bottomed lakes with shallow margins seem to be a good place to look.

After I got home from my trip, I spent some time in the front yard, and what did I see? An immature Spatterdock Darner on the tree in front of the house! I watcher her for some time, and I wonder where she emerged from. All told, I would estimate that I saw close to a hundred darners yesterday, so there would have been may thousands out there that I did not see, which really boggles my mind. It truly was a darner day.

Friday, May 25, 2012

May Trameas in Michigan

I was out at the small muddy pond in Pittsfield Preserve during my lunch hour today. It looked very much like a summer day -- breezy, humid, and 85 degrees. The small pond is slowly drying up and it is about 10% of the area that it occupied in March. I saw several Plathemis lydia, a couple of Anax junius, a Libellula pulchella, Ischnura verticalis and Lestes sp. I spotted my first Erythemis simplicicollis of the season, too. A little way away from the pond, I flushed out a Tramea! I watched the dragonfly until it finally settled down on some vegetation. I carefully walked up to it and netted it in the grass. It is a sexually immature female that looks like it has but recently emerged. This is the first Tramea lacerata that I have seen in May, though Julie and Darrin collected one on 5/26/2010 in Wayne County. If this emerged locally, it would have had to survive the winter, which of course, was quite mild this year. As I said before, this is going to be an interesting season.

Saturday, May 19, 2012

Aurora Damsel

I went back out to Embury Road today to see what has emerged since I was there 2 weeks ago. Lots of baskettails were in the air, and most of them seemed to be Epitheca cynosura. However, a few that I caught have the look of E. costalis. I guess I'll know after I can take a more measured look at them. There were also plenty of Boreal bluets, Enallagma boreale. Whereas two weeks ago they were mostly tenerals, today all I saw were sexually mature individuals, and quite a few were in tandem.

One of my favorite bluets is the Aurora Damsel, Chromagrion conditum. It's a very handsome damselfly with yellow and blue on the side of the thorax. They are more common as you go northward, but the wetlands along Embury Road have that nice mix of tamarack bog and grassy swales with some slight current that these damsels seem to like. The top of the thorax is not striped, but has a wavy-bordered black area, and there are no post-ocular spots on the head. I rarely see many of these at once, but do recall them being quite abundant when I studied the odes in the Huron Mountains in Marquette Co. Northwest Washtenaw Co. and probably parts of Waterloo Recreation Area in Jackson Co. have good habitat for this colorful damsel.

Another especially noteworthy catch today was a female Cordulegaster maculata, the Twin-spotted Spiketail. I did not expect to net one flying down the middle of Embury Road. There are some nice little streams fed by these swamps, and I suspect that she was on her way to the one near the road. I also saw a couple of Spatterdock darners, Rhionaeschna mutata, but they were out of reach. I managed to net an Amber-winged spreadwing - Lestes eurinus. All of the ones I saw were in the woods, and they had obviously emerged in the last 24 hours or so.

Sunday, May 06, 2012

A Memorable May 6 at Embury Road

Yes, it has been a strange spring so far. We had those incredibly warm days in late March, followed by a month of cool weather in April that flirted with some warm days, but also had some frosty nights with some fairly cool days in the low 40s to mid-50s. As April ended and May began we had a day last week in the mid 80s, followed by more typical weather with highs near 70. What did this weather do to the early emergers? There were reports of Enallagma and Ischnura out a few weeks ago in MI, but I think many of the species that emerge first have been waiting for a run of warm days and less chilly evenings. If today's visit to Embury Road was any indication, then a lot of odes have emerged in the past 4 days or so.

Okay, what is so special about Embury Road? It's one place that I have tried to collect at consistently in early to mid-May since the late 1990s. Located in the NW part of Washtenaw County, MI., it traverses a swath of wonderful habitats from North Territorial Road to Joslin Lake Road. A good chunk of the land is owned by the state and county, with woodland ponds, fens, marshes, seep areas, bogs, lakes and streams as well as some nice upland hardwood areas. It also connects to Park Lyndon N via a trail and boardwalk, so a lot of birders, butterfly enthusiasts, and nature lovers know about this place. My buddy Mike Kielb introduced me to the spot back around 1997, and I have visited it more than any other spot in the county.

Today's visit was not only a welcoming sign that the season has really begun in earnest, but it also was a nice way to get rejuvenated with a rewarding few hours in the field. I parked in my usual spot off the dirt road and as I walked around, I was amazed at the incredible numbers of Enallagma boreale that were flying low to the ground in the woods. Almost all were tenerals, meaning they had just emerged within the last day. I saw only a few that had mature coloration. That means that probably something like several million of these damselflies emerged over the weekend in one part of the county. That's an incredible amount of biomass, showing just how productive the ponds and lakes are in that area. Now I always see these around the 10-15 of May, meaning they are a bit earlier this year, but I have never seen them so numerous.

Plathemis lydia, sexually immature male.

I also am pleased by the numbers of baskettails that were flying. Almost all in that area are Epitheca spinigera and cynosura. I collected several, just in case E. costalis might be among them. A male and female E. spinigera were captured with many water mites attached to the venter of the abdomen. They definitely were slower-flying and the male especially looked strange, as the mites deformed the shape of his last few abdominal segments.

The underside of the ♂ E. spinigera with hundreds of water mites attached.

Plathemis lydia were extremely abundant -- I probably saw a hundred, whereas I only saw a few Ladona julia. Usually, the chalk-fronted corporals outnumber any other Libellulids early on. I saw perhaps a half-dozen Libellula quadrimaculata, and perhaps 50 or so Leucorrhinia intacta.

A resting ♂ Dorocordulia libera.

In the wooded trails, I encountered two Dorocordulia libera, both recently-emerged. These dainty racket-tailed emeralds are more common northward, but seem to do okay in the NW part of the county.

One of my first catches of the day was a male Spring-time Darner, Basiaeschna janata. It is our smallest Aeshnid, and I will bet that the one I caught emerged several days ago. I also stirred up a teneral darner that flew off into the woods, where I lost sight of it. Based on its size and location, my guess is that it was a Spatterdock darner, Rhionaeschna mutata. I saw a half-dozen Common Green Darners (Anax junius), and managed to catch a voucher. Notably absent were any Gomphus spicatus, which should be out soon. So, here is the tally of Odonata species seen/ collected/photographed today:

Enallagma boreale - bazillions
Ischnura verticalis - common
Anax junius - 6+
Basiaeschna janata - 2
Rhionaeshna mutata? -1
Dorocordulia libera - 2
Epitheca cynosura - many
Epitheca spinigera - many
Ladona julia - 6
Leucorrhinia intacta - numerous
Libellula pulchella - several - these are early!
Libellula quadrimaculata - 6
Plathemis lydia - very numerous

One of my favorite skimmers, Libellula quadrimaculata. They aren't so pretty after a few weeks, but are very brilliant when they are recently emerged.

Twelve-plus species is pretty darn good for the first week of May anywhere in Michigan. I will have to check my records to see how these dates stack up with previous years, but that's another story. Let's hope the rest of the season is as wonderful as today's!