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!

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