29 May 2009

Success! = Cordulegaster obliqua

Friday, May 29 started out with some great weather (sunny and calm) so I headed to Lower Huron Metropark at 1000 to obtain physical evidence of the spiketails.

Initially, I walked the forest edge in hopes of finding an adult Arrowhead Spiketail (Cordulegaster obliqua) to photograph. Unfortunately, I only saw one and it did a quick flyby at head height on the opposite side of the clearing and it didn't return.

Thus, it was time to check the rivulet. Ethan Bright hinted that I should dip for nymphs in the silty areas below the sticks and branches laying over the water of the streamlet. On about the sixth dip, I came up with a large nymph of a Cordulegaster.

This is the home of this nymph.

After identifying the specific structure of the nymph habitat, I began looking for exuvia. At 1130 and a bit upstream I "hit the jackpot" by finding an emerging female. Note the large ovipositor.

She was on a tree a few feet from the rivulet and is on the trunk at the left in the photo below.

Ethan Bright also noted that there may be different sizes of nymphs if these Cordulegasters require more than one year to mature. A bit further upstream I dipped a few more times and found another nymph which was a bit smaller than the first.

It was similar in habitat structure to the first, a hole below a log with a silty layer.

Given the couple of adults I observed over a few days and the nymphs being found relatively easily, it seems there is a decent population along this waterway. Nannothemis and I will return in a couple weeks to try and obtain good quality photos of the adults since there should be more flying.

I returned on 31-May-09 and found one male perched in a calm, sunny area at 1115. I was able to obtain only one photo, shooting through my binoculars.

25 May 2009

Early Gomphids and a life ode

I continued the search for the early darner by visiting Lower Huron Metropark. I am somewhat at a loss where to find the Springtime Darner (Basiaeschna janata) in Wayne County, but I'll continue searching this location as you'll read at the end of the post.

I started and ended at the Woods Creek Picnic Area. This is adjacent to the Huron River and has a small creek running through a wooded hollow that is great for clubtails (Gomphus sp.) this time of year. Immediately upon my arrival, I began kicking up recently emerged Ashy Clubtails (Gomphus lividus) along the two-track and on the adjacent vegetation.

Walking through the grass of the open areas, I kicked up a couple of recently emerged Midland Clubtails (Gomphus fraternus) which also happen to be a new early date for Michigan.
Here's a male:

And a female:
Soon after this I saw a life ode working the edge of the forest. Initially Dragonhunter came to mind, but I realized that it was too early for that species. The individual was large (50% larger than the clubtails I was examining) and black with bright yellow markings. The dragonfly was hunting along the bushes and small trees of the partly shaded opening. Then luck was on my side and it perched on a twig, hanging vertically from the tip.

Immediately, I recognized the following:
  • eyes touching at a point on top of the head = spiketail (Cordulegaster)
  • yellow arrowhead markings along the dorsal surface of the abdomen = Arrowhead (C. obliqua)
  • long ovipositor extending beyond the tip of the abdoment = female
No time for a photo as this female Arrowhead Spiketail (Cordulegaster obliqua) continued on her way.

I searched further and only had one more fleeting glimpse as she headed into the woods. While checking the immediate vicinity I found a small rivulet running from the hillside. This was a new water source that I wasn't familiar with and investigated further.

This looked like appropriate habitat from the little I knew of this genus. The water is one to a few inches deep and one to a few feet wide. The substrate was sandy with very silty and mucky areas.

This is one species I would have never expected to see in Wayne County (i.e., Detroit). There is one record of a male on June 14, 1931 in Detroit. In my mind, I had written C. obliqua off as an extirpated species for the county.

One never knows what can be found, even in the concrete jungle we call Detroit.

I returned the next day and had another brief glimpse of a hunting spiketail along the edge just before it began raining.

In future days, I'll check for flying adults, exuviae along the rivulet, or possibly nymphs in the water. Wish me luck!

24 May 2009

First summer-like day in the field.

I took advantage of the sunny afternoon to search for Springtime Darner (Basiaeschna janata), a species still needed for Wayne county, Michigan. My search involved a few locations in the northwest part of the county near Johnson Creek.

Location #1: northeast of the Ridge Road and 5-Mile Road. Johnson Creek is bordered a large wetland (grass and cattail) to the south and a new, sprawling subdivision to the north and east.
3 Eastern Forktails (Ischnura verticalis)
5 Emerald Spreadwings (Lestes dryas)

2 Common Green Darners (Anax junius)
1 Prince Baskettail (Epitheca princeps) - early date for SE MI
4 Common Whitetails (Plathemis lydia)
2 Widow Skimmers (Libellula luctuosa) - early date for SE MI
2 Twelve-spotted Skimmers (Libellula pulchella) - early date for SE MI

The wetlands are great for uncommon birds: Sedge Wren, Swamp Sparrow, Bobolink, Eastern Meadowlark....and one year there were Henslow's Sparrows.

Location #2: Johnson Creek at 6-Mile Road

Location #3: Fish Hatchery Park in Northville
2 Common Green Darners (Anax junius)

Thus, my search for an early non-Anax darner was a bust, but in the end it was a nice day to be out.

21 May 2009

1st multi-species day!

While out at lunch on May 20, I was happy to find multiple species in one location in Oakland County, Michigan.

During my lunch hour I was able to visit Lakeshore Park in Novi.
For species #1, a baskettail species (Epitheca sp.) was found patrolling one of the sunny trail straightaways.

Species #2 was a female Common Whitetail (Plathemis lydia) sunning herself at a trail crossroads.

The final and 3rd species was a Dot-tailed Whiteface (Leucorrhinia intacta). This was an upland grassy area. This individual was quite skittish and all I obtained was this poor photo.

20 May 2009

Second species of the season

While doing the North American Migration Count (NAMC) at UM-Dearborn on May 9, Nannothemis found a few Eastern Forktails (Ischnura verticalis). I didn't hear of it until later in the day so I returned on May 10 to find 13 individuals perched on the dewey grass.
Here are three of them:

18 May 2009

One in ten odes threatened with extinction

An article from the BBC reports on the results of a survey of the population and distribution of 1500 Odonata species from all over the world. One in 10 species is threatened, or categorized as critically endangered, endangered, or vulnerable. Species most at risk tend to live in southeast Asia (full of islands that have endemic species) and Australia (being impacted by climate change).

Too little data exist to accurately assess the status of many species. We often feel that while our contributions are small, we hope that they lend something to the collective knowledge -- now or in the future-- that will help with conserving these fantastic insects.