Aeshna walkeri

The male Walker's Darner is a restless beast. "Males patrol low over the water, meticulously checking the inlets and rocky crevasses lining the margins of pools in the streambed for females that have come to oviposit in seams of moss and the submerged roots of plants;" (Manolis 2003). That is exactly what this male is doing along the edges of the upper San Antonio River. In the photo below, he will go check into every nook and cranny of the tangled roots you can see, then quickly move on to the next such patch of vegetation upstream. He does this for several hundred yards, and then makes a return trip — time after time, hour after hour. Because he was predictable, this allowed me to wait for each brief appearance at try to snap flight photos. I have yet to see on that wasn't in flight. I've only seen one female so far, and she, too, was in flight (and not photographed).
photo (above and below) 23 Sep 2006
North Fork San Antonio River © D. Roberson
Identification criteria include (a) a white face with only a faint brownish stripe across it; (b) dark brown eyes; (c) very little yellow or green color on the thoracic stripes, which are instead usually quite white; and (d) broad paddle-shaped cerci on males. Our common Blue-eyed Darner has a blue face and blue eyes and different cerci. Paddle-tailed Darner has a black stripe across a yellow-green face and yellow stripes on the thorax. Although extremely difficult to see in the field, Walker's also has a very short spine at the low tip of the cerci while the spine on Paddle-tailed is a bit longer and extends beyond the end of the 'paddle.' [I.d. points from Manolis 2003]. Also, Paddle-tailed Darner has a large blue spot atop the final (10th) abdominal segment that is lacking (or very reduced) in Walker's Darner.
Walker's Darner also has a black pterostigma. You can see this is a few of these flight shots. This is (again) something that is hard to see in the field. Male Paddle-tailed Darner can also have a black pterostigma but all other species have a brown one (Manolis 2003). Shadow Darner A. umbrosa  has not yet been recorded in MTY but it is similar to Walker's in overall pattern (white white, brown eyes, no blue spot on 10th segment) and in behavior. However, it shows some yellow or green on the thoracic stripes and has a brown pterostigma. 
photo (above) 23 Sep 2006 © D. Roberson
Nacimiento River below Ponderosa Camp
Walker's Darner was first collected in MTY on 17 July 1943 along Finch Creek, adjacent to Hastings Natural History Reservation. The specimen, then housed as Hastings, was identified as 'Aeshna palmata' [Paddle-tailed Darner]. The record was not published but was eventually posted to Hastings' web site. The entire HNHR collection was eventually moved to the Oakland Museum, and this specimen was reviewed in August 2006 by Tim Manolis. The specimen, a male, has a very short spine on the lower tip of its cerci. Manolis correctly the identification to A. walkeri. This constituted a first county record. All other on the status and distribution of this species was obtained after than date, and primarily during work by D. Roberson in the Santa Lucias in Sep-Oct 2006. 

Walker's Darner prefers shady streams and rivers with appropriate riverside root-balls and vegetation. These are (so far) all in mountainous country in MTY. It has not been found on more sluggish rivers running through the lowlands.

So far Walker's Darner is known from MTY only from rivers and creeks running down the eastern slope of the Santa Lucia Mountains.  It occurs along the upper Carmel, San Antonio, and Nacimiento rivers, and various other creeks (e.g., Piney Creek, Finch Creek) that flow into these rivers or the Arroyo Seco. However, it occurs regularly in the mountains of San Benito County to the east, so might be expected along more permanent streams in the Diablo Range.

Walker's Darner is a late flyer. Dates range from 17 July to 7 October. These are similar to dates elsewhere in California, although some southern individuals fly into November.

Literature cited:
  • Manolis, T. 2003. Dragonflies and Damselflies of California. Univ. of Calif. Press, Berkeley.
Web resources:
Major identification web sites with much information on California odes include: For sites with excellent photos to compare for identification or to simply enjoy, see: Many of these sites have links to other useful pages. Kathy Biggs's site is particularly useful in her selection of links.

All photos © Don Roberson 2007


Page created 11 Feb 2007