24 June 2007

The blues

Last weekend when doing some bird survey work close to home in the urban jungle, Stylurus was surprised to find several Spatterdock Darners, Rhioaeschna mutata, in a small pond adjacent to the channelized portion of the Rouge River. This is a species we first had a glance at in 2005, and which eluded our nets at a retention pond in 2006 -- the first records for the county. Believe me, we know every wet spot in our city, and they've never been at this familiar pond.

It's locally referred to as "the oxbow pond," but in fact before the channel was built the river bowed in the other direction (the real oxbow ponds can be seen in the last photo below, to the left of the sewage plant), and this pond was either a natural wooded wet spot, or dug during construction.

It looks rather bucolic in the photo above. It's half-covered with spatterdock (Nuphar polysepalum), but one end and part of one side are being heavily invaded by phragmites. It's wooded around the rest of the perimeter. There are fish there (as a busy kingfisher demonstrated) which are probably larger and more numerous than past years, as the edges have become so thickly overgrown there is little access for folks who used to sneak in and fish there. The homeless folks have even abandoned their long-standing camp there.

Below, the red arrow points to the pond.

There's nothing sadder than a river in a concrete channel, in my opinion. This is the same stretch, just downstream of the pond. Ford world headquarters is the building in the distance on the right.

We returned yesterday, and Stylurus bravely made his way a few feet out from shore in the water at the only access point in the phragmites. I bravely tried to find access at the opposite shore, bushwhacking my way through sharp hawthornes, grape and poison ivy vines, and various discarded appliances. Along the margin, I was able to voucher one of a few Sedge Sprites, Nehalennia irene, a first for the city, and perhaps an indicator that the water quality is improving. Meanwhile, Stylurus was able to get the first voucher of the darner for the county.

This is the most beautiful of our darners, I think. This individual was bit battle-worn, missing half a leg and one foot. We did not observe any females, and the fish in the pond would prohibit much successful reproductive activity. So far, this has just been a terrific year for odonates -- nearly every species in abundance and in new places. To a great extent this likely reflects past conditions (up to two years ago) that allowed for greater dispersal of adults followed by increased survivorship of eggs and larvae.


MaryLou said...

Great pictures - having an interest in Dragonflies and Damselflies, I know how difficult it is to photograph them. Wonderful article.

Anonymous said...

Thanks for the comment, mary lou. Good luck getting some photos in the upcoming season. I can't wait until the odes start flying here in Michigan. However, we received several inches of snow last night so I'll have to wait a bit more.

Anonymous said...

What species exactly is this Darner? I may be missing where you state the information.

Anonymous said...

Spatterdock Darner -- first paragraph.