Sunday, September 29, 2013

Common Green Darner - Anax junius

The late Rich Stallcup, renowned birder and naturalist, often referred to the Common Green Darner as  "The Lord of June". This large and striking species is one of the most common and widely distributed dragonflies in North America. The bright green thorax makes it easy to spot as it forages high and low, often near a pond or other body of water. Occasionally you can find one hanging from foliage, like this one at a pond in Tiburon, which allows leisurely study or a photo.


The male is shown above, with a distinctive "t-spot" in front of the huge multicolored eyes, plus a bright green thorax and bright blue abdomen with a dark stripe running down the middle. Here's a crop from the above photo to show more detail:


On September 28th we visited the water treatment ponds at Ellis Creek in Petaluma, California, and were delighted to see  several Common Green Darners in tandem pairs, ovipositing into the mucky stuff at the edge of the pond, giving us our best-ever looks at this species.


The pair moved occasionally to a new location, and almost every time they landed a male Green Darner would divebomb the pair, apparently hoping to get him to release his mate. Feisty creatures, for sure.

There are 5 Anax species in North America, including our largest dragonfly, the Giant Darner, Anax walsinghami, with a wingspan of 4.5".

Sunday, September 15, 2013

Hudsonian Godwit - Limosa haemastica

A juvenile Hudsonian Godwit was spotted  in Napa County, California, on Sept. 11, 2013 and was still present on Sept 15. It forages in a farm pond southwest of Napa at the end of Buchli Station Road, in an area known as Huichica Creek WA, and has been seen by scores of enthralled birders.



The Hudsonian Godwit, Limosa haemastica is a species rarely seen by most. It breeds far to the north, at widely scattered tundra sites in Alaska and Canada, especially around Hudson's Bay. The species in a long distance migrant, capable of flying 5,000 miles non-stop from Canada to southern South America, mostly flying over water down the Atlantic coast. Most Hudsonian Godwits seen in the Pacific Northwest and in California have been juveniles, and are likely from groups nesting in southern Alaska. The wintering sites in South America are  along the coast of Argentina, and down to Tierra del Fuego! The next photo shows the godwit plunging its long bill into the mud of the shallow pond, where it then probed like the Dowitchers. You can see the black tail here, along with the nicely fringed back feathers.


The feeding mehtod of the Hudsoniancan be seen in a short video I took (click on the icons for "HD" and "Full Screen", lower right of the link): http://www.flickr.com/photos/lenblumin/9754810473/in/photostream

Next photo gives a good idea of the bird's size (15"), as it forages near the slightly smaller and more slender Greater Yellowlegs, which is about 14".


My favorite photo was taken as the light improved. The soft brown of the water reflects dried foliage from the bank of the pond, creating a perfect backdrop for the soft hues of the juvenile Godwit. Note the well-defined supercilliary mark, which is widest in front of the eye and stops just over the rear of the eye. Bar-tailed Godwit has a longer stripe here.


The long bill is gently upcurved, much like the Marbled Godwit's. The similar-appearing Black-tailed Godwit has a straighter bill with more color at the base. In the Hudsonian the pink color is restricted to the proximal lower mandible. Juveniles have an unmarked breast, are browner that fall adults, and have more brightly marked backs. The last shot show the Hudsonian with the American Avocet and a Greater Yellowlegs.


Taxonomy:

Order: Charadriiformes - Shorebirds, including Gulls and Terns

Family: Scolopacidae - Shorebirds, including Sandpipers, plus Avocets, Oystercatchers, Turnstones and Phalaropes.

Genus: Limosa - The Godwits. Limosa meaning "muddy", apparently a reference to the coastal mudflats where many of these birds forage. There are only 4 Godwit species in the world. Their relationship to other Scolopacidae is uncertain. Some evidence argued for placing them near the curlews, while other signs pointed to a dowitcher link in the past, or even to the turnstones.
  • The largest Limosa is the Marbled Godwit at 18", a bird commonly seen from fall to spring on our coastal tidelands, but not seen as widely in most other areas. Total population about 130,000.
  • The 16" Bar-tailed Godwit, a Eurasian species numbering over 1 million, has some 120,000 breeders sited in Alaska along the north and west coasts. It is thought that the rare sighting of Hudsonian Godwits in Australia occur because they follow the Alaskan Bar-tailed Godwits on their epic 7,000 mile journey south across the Pacific.
  • The 16.5" Black-tailed Godwit is also Eurasian, numbers about 800,000 and is closest in appearance to the Hudsonian Godwit. Underwings are white, and bill is straighter than that on the Hudsonian. Black-tailed is clearly closest to the Hudsonian and they are referred to as allo-species, or classified as conspecifics.
Species: Limosa haemastica - Hudsonian Godwit. Total population is estimated at 50-70,000. No subspecies are currently recognized, as the disjunct populations are all similar in appearance, but genetic analysis show distinct difference among the separate breeding groups. The Hudsonian is best distinguished from the Black-tailed by the black axillaries and underwing, which we saw briefly when it flew to the other pond nearby. Vagrant Hudsonian Godwits have been seen in various Pacific Island groups, in small numbers. Read more about this rare visitor on Cornell's Birds of NorthAmerica Online, #629, Elphick and Klinka.

To see the exact location on a map you can scroll down a bit more and click on "Napa, California".

Tuesday, September 10, 2013

White-belted Ringtail - Erpetogomphus compositus

Leslie Flint spotted this male White-belted Ringtail, Erpetogomphus compositius, hunting low near a riffle along Bear Creek, August 28th. She followed it to a perch, where it obliged us by staying a while for photographs. 

The White-belted Ringtail has an well-chosen scienticfic name, as compositus suggests that may have very varied features. Indeed, it looks like a colored drawing filled in by a artistic youngster. Gray face, blue-gray eyes, multi-colored stripes on the thorax, white-rings along the black abdomen, and yellow-orange on the last 3 segment of the abdomen that form the "club" on the male. The female looks similar, but without a clubbed tail end. 


The Ringtails, genus Erpetogomphus, include about 22 speciesof which 6 are seen in Western U.S. (Paulson), but only 2 in California (Manolis). Ringtails are restricted to the Americas, whereas other clubtails may have a worldwide distribution. Like most Clubtails, the Ringtails are found along rivers and streams, usually those with a gravel or sandy bed. Most of the 22 species are more green in color that this wild composite. Here's a closer view of the remarkable eyes and face:

Cropped view of the White-belted male, to show face and thorax detail
The Ringtail are just one of about 13 genera of dragonflies that make up the Clubtail family called Clubtails, the Gomphidae. The Clubtails as a family are indeed very diverse, with at least 13 genera seen in the U.S., including Sanddragon, Leaftail, Forktail, Hanging and Pond Clubtail, Common Clubtail, Least Clubtail, Spinyleg, Dragonhunter (gotta love that one!), and Grappletail. All Clubtails have widely separated eyes (check out the close-up above), compared to the eyes of most dragonfly families where the eyes are close and often touch at the midline, and most are found along rivers and streams where they choose a horizontal perch. Worldwide, there are a total of about 90 genera in the Clubtail family, numbering some 900 species. Quite a group to study, although not nearly as numerous as the Skimmer family,Libellulidae.

The Clubtails are one of the 12 families that make up the suborder of Dragonflies, Anisoptera. Families seen in the U.S., besides the Clubtails, are the Petaltails, Darneres, S;piketails, Cruisers, Emeralds, and Skimmers.




Sunday, September 1, 2013

American Rubyspot - Hetaerina americana

Exploring Bear Valley Creek (Colusa County) with the able guiding of Leslie Flint, we quickly came upon one of our targets for the day, the American Rubyspot, Hetaerina americana. These good-sized damselflies (about 1.75" long) are as big as some dragonflies, and their colorful broad wings make them easy to spot. They prefer streams and rivers with emergent vegetation, and have been seen in all lower 48 states except WA and ID.




The individuals we saw first were females, with purple-brown abdomen, light stripes on the thorax and a striking purple on the face and eyes. If you don't like Rubyspots then you definitely don't like dragonflies, because they don't come much prettier. The female has color all along the front of her wings, whereas the male (to follow) has large dark red spots at the base of the wings. Both are show-stoppers.


Recently I wrote about the Pond Damsels, a.k.a. Narrow-winged Damsels, a big family. The Rubyspots belong to a smaller family, the Broad-winged Damsels, a.k.a. Demoiselles. The scientific name for the family is Calopterygidae, which means "beautiful wings". (Botany fans no doubt remember that Calochortus means "beautiful hair".) I haven't seen Rubyspots in the immediate Bay Area, but we did see them on a trip to Pine Flat Road with Kathy Biggs, where they were found along the Russian River (Alexander Valley).


Now for the male:


The male American Rubyspot is difficult to describe, as the experience of viewing one is more visceral than one might expect from watching a perched insect. These photos don't capture the intense ruby color of the spot on the inner wing, but that's good, as it allows the eye to better see the rest of his finery. The male lacks the pterostigma (a.k.a. "stigma") so often seen in dragonflies along the outer leading edge of the wing. The female Rubyspot usually shows a small white stigma, although not obvious in the ones I photographed.


Another view:


So, just for review, damselflies, suborder Zygoptera, are small to medium-sized odonates whose eyes are separated and often look like they are on stalks. In dragonflies the eyes are bigger and often touch in the midline. Damsels usually have comparatively thinner abdomens, and their forward and rear wings are similar, whereas dragonflies are often stouter, and the forward wings differ in shape from the rear (that's what Anisoptera literally means). Damsels usually keep their wings folded together when perched, either above the body as in the Rubyspot, or alongside the body. The Spreadwing family of damsels is the exception, you would guess from their name.

Taxonomy: 

Order: Odonata Dragonflies and Damselflies

Suborder: Zygoptera Damselflies (5 families: Jewelwings, Spreadwings, Shadowdamsels, Threadtails and Pond Damsels.

Family: Calopterygidae - Broad-winged Damsels, or Demoiselles (Jewelwings). Demoiselle was old french for a young woman, or a "damsel". Here in the U.S. we find the Jewelwings (5) and the Rubyspots (3) to represent the family. But there are 3 other genera of Broad-wings seen elsewhere.

Genus: Hetaerina Rubyspots. They are mostly tropical, with 37 species. 3 are seen in the U.S. - the other 2 are the Canyon Rubyspot and Smoky Rubyspot.

Species: Hetaerina americana American Rubyspot. Maybe we should nominate this species as our "national dragonfly", or should we wait until it's recorded in WA and ID?