Saturday, July 26, 2014

Wandering Tattler - Tringa incana



Recent trip to Bodega Bay included views of the Wandering Tattler, Tringa incana. At Bodega Head we had good scope views of 2 Wandering Tattlers, on the rocks below the whale-watching area.The birds were foraging on wave-swept rocks about 75 yards from our viewpoint. First photo is the un-cropped original. The medium-dark gray back makes it hard to pick out when the background is rocky or covered with mussels.


The second cropped version is only 9% of the full size, so details and sharpness are lacking - just not enough pixels on the bird! Note the white supercilliary, especially in front of the eye, as well as the extensive barring, as seen on some of the "shanks". 


Tattlers passing through along the California coast in July are adults in alternate plumage, all dark gray above and strikingly barred below. Juveniles will pass through from mid-August to September. The Tattlers breed mostly at higher elevations across Alaska, and into both far-east Russia and northwest Canada. They migrate south from mid-July thru August, and are seen at rocky locations and jetties all along the coast. Many will end up in Central or South America for the winter while others have already headed on in a transpacific journey to the many islands of the Pacific, from Hawaii to Indonesia and New Zealand, and almost every island in Oceania. They are fairly solitary birds, seen mostly as individuals or groups of 2-3 birds. Total world population may be no more than 25,000 birds.

When watching the Tattlers (there is a second species, the Gray-tailed Tattler, a rare vagrant here) one is struck by the teetering tail movements, much like that of the Spotted Sandpiper.



Sunday, July 20, 2014

Vivid Dancer - Argia vivida

Damselflies are a challenge, especially for a relative beginner like me. Young damsels emerge with soft bodies and weak wings, and are called tenerals. They're rather devoid of color and markings, so identification is difficult. The first 2 photos show a large tan teneral damselfy that we saw at Lake Lagunitas on Wednesday most likely a Vivid Dancer, with terminal appendages that suggest it might be a male. The young damsel flew weakly on glistening wings, moving 3-6' each time as if looking for a sunny spot in the dappled shade of the picnic area along the creek below Lake Lagunitas dam. Note how the 4 wings are held together above the abdomen, like a sail, a characteristic of the Dancers (Argia), wheres the Bluets (Enallagma) usuallt hold their folded wings lower, on one side or the other of the abdomen.



Teneral dragonflies are relatively devoid of color, but as the exoskeleton hardens color gradually appears, along with field marks that can make identification more positive. In the case of the Vivid Dancer the male will get a brilliant blue on the thorax and abdomen.  Details on the thorax are also helpful and include a think black dorsal stripe and a humeral stripe on the side that thins out or disappears at its midpoint.


 The female can be blue (andromorphic) or tan (gynomorphic), or other shades. The black markings are unique, with teardrop-shaped spots on the sides of the middle abdominal segments, as seen in this pair of Vivid Dancers in tandem position.



Variegated Meadowhawk - Sympetrum corruptum

Patti and I joined a dragonfly outing led by Tim Manolis on July 12th at Bear Creek, which is along route 20, east of Williams. It's usually hot there in the summer, and even this dry year produced an abundance of dragonflies. By far the most common species was the Variegated Meadowhawk, a rather easy species to observe as it frequently chooses an open perch and tends to ignore the approach of humans. Contrast that with the Giant Darner, a green darner with the distinction of being the largest dragonfly in North America. Our group got to see several Giant Darners, but they patrol along the creek tirelessly and never seem to land. This digiscoped shot shows the distinctive thorax marking, with pale blue stripes ending in a yellow dot. Lack of red color on the abdomen suggests it is either a young male or a female.





The mature male Variegated Meadowhawks, with red on their abdomens, were present in good numbers and showed a lot more red on the abdomen. Here's an example taken at Ellis Creek a few years ago.


Last shot (below) is another one lacking red on the abdomen. Perhaps an experienced ode lover could better determine the age and sex, as the terminal appendages are seen more clearly here. See taxonomy below.



Taxonomy-

Family: Libellulidae, the Skimmers. Big family, worldwide.

Genus: Sympetrum, the Meadowhawks. 15 species in the U.S., 10 of them found in California (T. Manolis, Dragonflies and Dragonflies of California, a must-have reference for California odonata).

Species: Sympetrum corruptum, the Variegated Meadowhawk. A widely distributed and common migratory meadowhawk, found from southern Canada and to points south, and across to Asia.

Migration in dragonflies is a fascinating and a relatively new area of study, where we can all contribute valuable observations. See: http://blog.nature.org/science/2013/09/16/dragonfly-migration-a-mystery-citizen-scientists-can-help-solve/

Wednesday, July 2, 2014

Black Spreadwing - Lestes stuctus

The Black Spreadwings here were seen with Leslie Flint on a trip to Nagasawa Park in Santa Rosa, June 9, 2014. We watched about a dozen males nervously flitting about in a moist meadow near the parking lot.  At times they perched to give a decent view, hanging from grass with abdomens downward. The male is dark on the top of the abdomen, often showing a bronzy sheen, especially when younger, as seen here.


Lower parts of the abdomen are light blue, and the eyes are bi-colored blue.



Better photos might show that the dark pterostigma ("wing spot") has white color at the ends. This was my very first spreadwing damsel, so it was an exciting day. The Emerald Spreadwing, found at higher elevations, is similar, but with an emerald sheen. The experts think the Black and Emerald may be subspecies, and could be lumped together in the future.

Taxonomy:

Order: Odonata. The Dragonflies, including the Damselflies. Over 5,000 species worldwide.

Suborder:  Anisoptera ("unequal wings") - The Dragonflies. Bigger, thicker bodied, wings held spread apart, eyes large and often touching at midline.

Suborder: Zygoptera ("equal wings") - The Damselfies. Smaller, wings usually held folded, eyes smaller and separated. 41 species of damsels are found in California, but that will likely change in the future as we get warmer.

Family: Lestidae - The Spreadwing Damsels. As their name implies, the spreadwings usually keep their wings spread when perched, except at night or when being harassed. They tend to be larger than other damsels. 19 spreadwing species are found in the U.S., with 7 species documented in California. Worldwide there are 84 spreadwing species.

Genus: Lestes - The Pond Spreadwings. 5 species in California. The other spreadwings here are 2 species of Stream Spreadwings, in the genus Archilestes.

Species: Lestes stuctus - The Black Spreadwing. Range limited to California and Southern Oregon.

Grappletail - Octogomphus specularis

The recent heatwave made for good dragonfly hunting. On a warm and breezy May 12th  I met Leslie Flint to check out the odes at Lake Lagunitas and Bon Tempe Reservoir, Marin County, California. The highlight for me were the Grappletail wars, as 10-12 males vied for prime spots on sunlit rocks in the creek just below the Lake Lagunitas dam. The main strategy seemed to be a rapid approach from almost any direction, usually resulting in the roosting Grappletail taking flight at the threat, "just in case", yielding to the newcomer. Somewhat surprisingly this tactic sometimes worked for the feisty Vivid Dancers, present in large numbers at this same spot.

The Grappletail is in the Clubtail Family (Gomphidae), and is in the monotypic genus Octogomphus.


First photo (above) shows a confusion of wings, as the strong overhead sunlight cast sharp shadows of the wing veins. The shot is pretty good for the terminal "grappletail", as well as the long thin abdomen that ends in a distended clubtail shape. Second shot (below) shows the remarkable urn shape on the dorsum of the thorax, a striking and unique fieldmark.



Some text from an email in July, 2012, when we found Grappletail on a trip along Pine Flat Road led by Kathy and Dave Biggs:

"Grappletails have very slender abdomens (compare the diameter to that of the thorax), which increase in thickness toward the back end, especially in the male. As you might guess, the bulge at the end gives the name ' clubtail'.  The names of the various clubtail genera are varied and  creative, including the Sandragons, Leaftails, Forceptails (Greater and Lesser), Pond Clubtails, Common Clubtails, Hanging Clubtails, Spinylegs, Dragonhunters, Ringtails, Snaketails, Least Clubtails, and of course the Grappletail. The last is not pleural because there is only one species in the monotypic genus, Octogomphus specularis, the Grappletail.  Some of these sobriquets would perhaps serve well for a street gang or a videogame!"