24 June 2011

A confirmation & reconfirmation for Wayne County

Looking to fill in gaps of the Wayne County, Michigan, odonata list, I had decided to visit Crosswinds Marsh, phase I, on June 11, 2011.

There is a nice loop (Blue Heron Trail) that hits a variety of habitats that I was visiting last fall and I was hoping for a missing early season darner or a Spangled Skimmer. No luck for either, but one does have to get into the field to have a chance.

Surprisingly, there were a large number of Aurora Damselflies (Chromagrion conditum), a species we do not see often. Many were coupled:

Here's a closeup of a male showing the yellow area of the thorax:

Hanging out on a culvert for Disbrow Drain was this male Unicorn Clubtail (Arigomphus villosipes):


I find this species very difficult to catch, unless one lands directly in front of the net. Thus, the digiscoped image through my binoculars is the best I can provide.

Pleased with the population of Aurora Damselflies discovered, I was hiking back towards the car and paused at the Mallard Trail boardwalk. A smallish, dark ode flew by that had brilliant, green eyes. Initial thought was baskettail (Epitheca sp.), but the body was looking solidly black and the eyes were like emeralds. Eureka!

I called Julie to tell her of the interesting sighting, and she also asked if it was a baskettail. Just then, the dragonfly flew back near me. Ending the call quickly, I was able to swing the net and capture the individual. It was a male emerald (Family Corduliidae), but I have little experience with any species other than Mocha (Somatochlora linearis). We just don't have bog or fen habitats in our home county.

Identification would have to wait until I returned home and we reviewed our references.
Examining the wing venation and the claspers confirmed the species as Racket-tailed Emerald (Dorocordulia libera). This is the first confirmed record of this species for the county!


Interestingly, Julie thought she had seen an emerald in the same area ~10 years ago, but dismissed it as a baskettail. There was a literature record from the 1870s, but this was to be removed from the county list since there is not voucher available and the records from that time period can be quite confusing. Sometimes locations of "Detroit" in the historical records seem to be related to the ship's port of call (typical transportation in that era), rather than the actual sighting or voucher location.

Anxious for Julie to see a live individual, we returned on June 19. A half hour or more was spent in the area of the original sighting with no luck. (Although, I thought I had an individual fly by at one point.) We slowly worked our way to the western boardwalk, while I tried to flush odes from the adjacent vegetation. We did see our first Halloween Pennants (Celithemis eponina) and Eastern Amberwing (Perithemis tenera) of the year. I pushed farther into the vegetation and flushed a couple female Slaty Skimmers (Libellula incesta), when a coupled pair of smaller, dark dragonflies flew in and perched in front of me. Racket-tailed Emeralds! Julie came over quickly with her good camera and was able to observe and photograph these cooperative individuals.

Mission accomplished and we have confirmation these are breeding in the vicinity. Julie once again has to revise her manuscript on Wayne County species, which she is hoping to submit for publication in the next couple of months.

2 comments:

upinthecosmos said...

Great pictures! I love dragonflies but rarely see them so I'm loving your blog:-)

Darrin O'Brien said...

Thanks for the comment. Hopefully we can continue to show some of the less common odes as the summer progresses. We're working on a paper of the dragonflies for our urban county. We've been quite lucky so far this season.