The summer months offer birders a good opportunity to get out and look for dragonflies. If you a large blue dragonfly hovering or patrolling over an open area, it is likely to be a "darner", and right now the largest ones with blue eyes around here (coastal northern California) are the Blue-eyed Darners, Rhionaeshna multicolor.
Recently I had good looks at Blue-eyed Darners (and a number of other dragonfly species) at the pond behind the library in Tiburon, along Tiburon Blvd. I think it's called Tiburon Marsh, and it offers several spots where you have open views of the water and emergent vegetation, prime spots for dragonfly mating.
There were a fair number of male Blue-eyed Darners patrolling the pond and nearby fields, hoping perhaps for the appearance of an elusive female, who appears near water only to find a mate., After getting fertilized she does the egg-laying on her own, with no male carry her in tandem and/or to guard her from other males. First photo show a pair in tandem position. The female has browner eyes and body, with yellow stripes on the thorax, although she sometimes bears a closer resemblance to the male.
The male sometimes hangs vertically on reeds or grass near the shore. This one preened his eyes much as a bird might preen its feathers. Check out the appendages at the tip of the abdomen, the structure of which can sometimes differentiate between otherwise similar Darners. Second photo is the Tiburon Marsh, with a good view of the intensely blue eyes and the paler blue face. The similar but smaller California Darner has eyes that are less blue, and perhaps a paler face. The California Darner also flies earlier in the season, although there is considerable overlap.
I was able to catch some of the eye-cleaning action of this male in a digiscoped video:
(Click on "HD" lower right, and then "Full Screen" icon just to the right):
3rd photo is from the Sacramento Wildlife Refuge, 2 years ago, taken right near the visitor center.
The Blue-eyed Darner if common across the western U.S., and is found as far south as Panama. They eat a wide variety of flying insects, and pretty much take them only on the wing, dining on mosquitos, flies, butterflies, moths, etc.
Taxonomy:
Order: Odonata
Family: Aeshnidae - The Darners.
Genus: Rhionaeshna - The Neotropical Darners, with over 40 species. Most are tropical (duh), with only 4 species seen in the U.S., and only 2 in California, the Blue-eyed and California Darners.
Note: Another similar Darner genus is Aeshna, the Mosaic Darners. In 2003 the Neotropical Darners were split from the Mosaic Darners. The Aeshna darners lack a bump under the first abdominal segment.
Species: Rhionaeshna multicolor, the Blue-eyed Darner.
To see all of the neotropical darners:
http://en.wikipedia.org/wiki/Rhionaeschna
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