Saturday, October 15, 2011

Fun With Darners!

The sun made an effort to shine this afternoon (with variable success), and temperatures hovered around the very low 60s. I figured I should take the opportunity to get out and see what I could find flying, so I wandered the grounds and trails of the Columbia Springs Environmental Education Center in Vancouver, Washington.

There wasn’t much variety. Other than a single meadowhawk (Sympetrum) that I spooked from a walkway, all I saw were darners (Aeshna). Two species of Aeshna, Paddle-tailed Darner (A. palmata) and Shadow Darner (A. umbrosa), are particularly common and widespread across the Pacific Northwest during the latter part of the season—mostly from around July on; into November if there are lingering warmish, sunny days. These two species are also very similar in appearance, at least superficially, and are often found flying together.

Today I saw a few darners patrolling the wetlands or hawking insects high overhead, but most of the action was at patches of Himalayan blackberry where many darners were perching and soaking up as much solar energy as they could. The best spots were along trail cuts in the blackberries where the darners would perch on the bramble “wall” that was facing the sun.

Perching darners don’t often let you get very close and they very frequently fly off before you even spot them. I tried really hard, moving slowly and stopping periodically to scan the sun-soaked vegetation before continuing. I did spot some perching males and I was able to photograph a few of those before they took off, but many more got away. I don’t know how many times I stopped to look over the vegetation, not see anything, then spook up one or more darners that were right in front of me as I started moving again. The colorful males are hard enough to spot while they’re perching, but the relatively dull females are even more challenging. I was able to photograph one female which reperched shortly after I spooked it.

Once you spot a perched darner, you have to approach very slowly and make no sudden moves. Some individuals are more approachable—maybe because they haven’t warmed up enough, and I was even able to catch one by hand for a few in-hand photos (I didn’t take a net out with me today).

I plan to offer a thorough comparison of these two darners in a future post, so for now I just offer you a few photos from today. I’m going to leave them unidentified for the time being, but both Paddle-tailed and Shadow Darners are represented. See what you can do with them and feel free to comment on what you think each one is.

A male...


Another male...


A female...


A hand-held male...



5 comments:

  1. I would say the first male is a Shadow Darner, considering the absence of abdominal blue spot on 10th segment and spots are small on each segment. Also the spots on the front of thorax look like an upside down foot print (not an official criteria ;-)
    the second male is most likely a Paddle-tailed, with the blue abdominal spots conspicuous on 10th segment, much bigger abdominal spots in general.
    The female has very small abdominal spots, thin lateral spots on thorax, I would say Shadow darner, but it would be easier seeing the under side of the abdominal segment (small yellow spot)
    The hand held male has narrow lateral spots on thorax, and no lateral spot on the first abdominal segment (although I am not sure if this is an official criteria, but after looking a many pictures, it seems to be the determinant, please let me know if I am mistaking), so I would say Shadow Darner

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  2. @Stephane Pissavin Excellent, Stephane! You're right on all counts. When I can get around to a thorough comparison of the two species, I'll point out a couple more helpful field marks as well as some potential pitfalls. Nice job!

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  3. Sandra Hunt-von ArbOctober 16, 2011 at 1:31 PM

    I came up with the same ID's - On the first two using the paired blue spots or lack thereof on the 10th segment. The female was more of an educated guess, so I look forward to your descriptions. As far as the hand-held male, the yellow thoracic stripes becoming green on top in the rear facing "flags" was the field mark I used.

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  4. @Sandra Hunt-von Arb Good job, Sandra! There are some pitfalls associated with some of those field marks (because of variation) to keep in mind, although they are generally useful. I recommend that you don't rely on any single color/pattern character, but I'll cover all of that later. I just need some time to write the post!

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  5. Stephane Pissavin, Vancouver BCOctober 17, 2011 at 7:03 AM

    Thank you Jim,

    I am not yet very familiar with all species from the NW as I moved from Europe to BC not too long ago, but there are very useful resources online to get to know the species. I especially enjoy browsing through the live scans from UPS website (amazing pictures !), as well as the various identification keys available (for BC, Wa, Or)

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