Hybrid Dabbling Ducks

During the past week a lot of ducks have been passing through the bay area. At fresh water sites the dabblers have been well represented, although many seem to just stop for a while to refuel before heading further south or to the central valley. Today at the Las Gallinas water treatment ponds (San Rafael, CA) we spotted an unusual Cinnamon Teal along the shore, partly obscured by the cattails.

The shot above shows the typical blue wing patch of the Cinnamon Teal, as well as the dark spatulate bill and orange feet, but the gray-blue ptch above and behind the eye, as well as the  black spots on the breast and flanks seemed to indicate the presence of other dabbling duck DNA. One possible explanation would be a hybrid bird, Cinnamon Teal x Blue-winged Teal, which are said to be common, and I have seen a few internet photos of such a hybrid that resemble this bird.

Above we get a different view of the gray patch on the head, partially outlined by a white white line as we sometimes see on Green-winged Teal, especially on the Eurasian Green-winged. The color of the iris seemed to be a deep brownish red.

Shot above better highlights the similarity of the head strip on the hybrid Cinnamon drake, with that of the male Green-wined Teal sleeping nearby. Similar shot below, with a probable female Cinnamon Teal on the left. I'm favoring Cinnamon Teal x Green-wined Teal as the ID for this bird, but of course that is speculative.

Last week at Corte Madera's "Shorebird Marsh" I spotted a hybrid Northern Pintail, with a pretty buffy patch on his cheek. Distance precluded a sharp shot, but the green iridescence on the side of the head suggested some Green-winged Teal DNA at work. The scapulars and tertials strongly suggested Pintail, as did the bill.

Here's another shot, showing the buffy cheek and bill somewhat better:

And lastly:

Eclipse Dabbling Ducks

In September and October each year we see a confusing array of atypical-looking ducks as they molt from eclipse (basic) plumage into the more familiar breeding plumage of winter and spring. I've found that as with passerines it helps a lot to focus first on the bill and face of the bird before checking out the rest of the bird. These photos, from Las Galinas ponds in San Rafael, are not as sharp as I would have liked, but since I learned something from each one I figured they are worth sharing.

The eclipse Cinnamon Teal drake looks a lot like the female, but the red eye gives him away. Note the Shoveler-like bill and "plain" face, i.e. no dark line through the eye.

The Eurasian Widgeon was puzzler, as its color was almost like a Cinnamon Teal, but the bill clearly said "wigeon", and it was much too red to be an American Wigeon. The female Eurasian Wigeon can often be warm in color, but never quite so warm as this drake. There is no real black border where the bill meets the face, as seen on American Wigeon. Same bird viewed 10 days later began to show some buffy color on the forecrown, and a hint of gray on the shoulder.

At times there have been up to 3,000 Northern Pintails at the ponds, but numbers down to perhaps 600. Very instructive to seem the males in every stage of molt from eclipse to breeding. The male here has the plain brown face we see in the female Pintail, but his beautifully trimmed steel blue bill gives him away. We can also see the beginning of fine vermiculations on the side of the body.

Here's another Pintail that is a bit further along in the pre-alternate molt:

The eclipse Gadwall looks a lot like the breeding male, save for the lack of vermiculation on the body. Here he's showing the cinnamon wing patch, formed by secondary coverts on the top of the wing, best seen in flight. Female and juvenile Gadwalls have some orange on the bill.

Lastly, here's a male Northern Shoveler from early September. I suppose it could be a juvenile, but the bright yellow eye is more consistent with an adult eclipse male.

Anna's Hummingbird - Subadult male - Calypte anna

Ducks have been returning to the San Francisco Bay Area for about a month, many of them in the confusing molt between eclipse plumage and the alternate or "bright" plumage of winter and spring. Of course all birds molt, but I don't remember seeing this take place in such vivid detail as on this subadult male Anna's Hummingbird seen this morning along Strawberry Point during a waterbird survey for the Richardson Bay Audubon Center.

These 3 shots were taken in succession. It was amazing to see the array of colors shown by this individual, with a palette that changed with very small changes in his posture. 

Iridescent colors in birds colors produced by the structure of the feather, akin to how colors produced by a thin film of oil on water (interference pattern). Blue colors in birds are also created by feather structure, but by a process that involves the selective scattering of reflected light, based on short wave length.

Those interested in the physical base for these phenomena may want to check these sources:

Why Are Hummingbirds Iridescent? (from Johnsgard book on N.A. Hummingbirds)

The Color of Birds (Stanford)

Structural Color in bird feathers (Wiki, somewhat technical)

Eared Grebe - Podiceps nigricollis

Right now (October 7, 2014) Eared Grebes are present in pretty good numbers, so I couldn't resist taking some shots of this one as it navigated around the Canada Geese and dabbling ducks at Las Gallinas ponds. When I got home I realized that the shots were interesting shots, as the 2 photos, taken 6 seconds apart, show how the features of a bird change with posture and activity.

First shot is a typical Eared Grebe posture, with a steeply sloped forehead, a peak of the crown above the eye, and the high-riding stern. 

Soon thereafter it began to swim faster, anticipating a dive, and the feathers became more streamlined. The forehead slope is now more shallow, like a Horned Grebe's, the peak of the crown a bit behind the eye, and the butt end is sleeker and low-riding.

I think this is young bird, molting into its "first basic" plumage. Note the amber/orange iris, as opposed to the redder iris characteristic of the adult Eared Grebe. The typical "first fall" birds are browner, but I imagine there is a fair amount of variation.

Northern Shoveler - Anas clypeata

In September the ducks return to the San Francisco Bay Area in good numbers, but most will be starting molting from their cryptic eclipse plumage into the bright breeding plumage they wear most of the year. Juvenile ducks and male duck in eclipse plumage often strongly resemble the adult female, so identification can be a challenge.

The Shoveler shown here was seen on Sept 17 at Las Gallinas. I figured it was a female Northern Shoveler, but several features suggest it may well be a male in eclipse plumage. The yellow-orange iris is similar to the bright yellow in the adult male, whereas juveniles and females have a browner iris. The head is a dark gray, while females and young shovelers would be more brown. The chest, breast and flanks on this birds have an attractive rufous wash, unlike the muted browns seen on females and youngsters. Bill color much like a female's, but the male's bill will only become black in full adult breeding plumage. So I'm going the an adult male in eclipse plumage.

Here's an older shot of a female. Note the brown iris and pale brown head.

Male Shovelers go through a more variable and prolonged molt than most other dabbler species, so most of them won't display the deep green-black head, rich chestnut flank color and striking white breast until late November.

Seaside Dragonlet - Erythrodiplax berenice

When in Connecticut we do most of our walk along Long Island Sound (Milford to Madison), rather than inland. In past  years we've spotted the small Seaside Dragonlet, Erythrodiplax berenice, but usually just the black male. This year, along the trail to Meig's Point at Hammonasset State Beach we saw a number of female Seaside Dragonlets, and were taken with their striking colors. Here's a "striped" female:

The brown wash at the mid-wing  apparently a clinal variation. Toward the end of the abdomen you can see the ovipositor, an extension of what is called the subgenital plate.

This view shows the brown wash a bit better:

The striped thorax and bright orange abdomen really stand out, but we learned that as the females age many of them will get quite dark, both on the thorax and abdomen, in the manner of the male. Here's a shot from late July 2012, at an East Haven salt marsh along Cosey Beach Avenue, showing a black female in tandem.

Males are usually easier to find, as they are the only small black dragonfly seen in seaside locations:

Another male:

And lastly:

Some taxonomy -

Family: Libelluidae - Skimmers and allies. Biggest dragonfly family, with 1,000+ species.

Genus: Erythrodiplax - Dragonlets. Large genus of mostly tropical new world skimmers, small to medium in size, with about 60 species. Only about 6 dragonlet species seen in the U.S.

Species: Erythrodiplax berenice - Seaside Dragonlet. They fly from mid-May to mid-September. Eat small insects and even small damselflies. Lay eggs only in salt water, even hypersaline alkaline lakes. Couldn't find any other U.S. dragonfly that oviposits in salt water.