Bonaparte's Gull - Larus philadelphia

Gulls can be difficult to identify, with many exhibiting similar patterns: gray above, white below and black wingtips. The small Bonaparte's Gull is a exception, easily standing out from the other local gulls. It flies and feeds more like a tern, diving suddenly to deftly pluck prey from the surface of the water, then resuming its back and forth flight about 20 feet above the water. Not easy to take a photo like this with a scope!

The black ear patch is present on both juvenile and adult birds, but not seen on other local gull species. The black tail band and striking dark carpal bars on the wings are hallmarks of a first winter bird. Note also the black trailing edge on the wing, another feature of a young bird.The dainty tern-like black bill and white eye ring complete the picture. A very pretty gull indeed!

Photos were taken this past week at Las Gallinas, where 2 juveniles birds have been foraging. As usual they were taken through a spotting scope, which takes a bit of luck, as the birds forage so actively and its hard to track them at 25X magnification. Here one of them rests briefly on the water.

Red-necked Grebe - Podiceps grisegena

A Red-necked Grebe (Podiceps grisegena) has been present at the Las Gallinas water treatment ponds since November 5th, and we're hoping it will stay the winter. It seems to be successfully foraging, mostly in the east end of Pond #1 and usually in front of the "island" where the BC Night-Herons roost. Yesterday it got close enough for some photos, which although back-lit still provides a good study of head and bill shape. 

The large size (at 18" it's a little bigger than the Ring-necked Ducks seen there), yellow bill and dark brown iris make it easy to distinguish from other grebes. The relatively stout neck and head shape, along with the bill, might suggest a loon at first. The dingy gray of the neck and the way the gray extends back from the chin and then up behind the "ear" brings to mind the Eared Grebe, but in fact the Red-necked is more closely related to the Horned Grebe (and to the Great Crested Grebe, which is not seen here). This is probably an adult RN Grebe, as the juvenile often shows some brown or chestnut color on the foreneck, as well as a lighter-colored iris.

The Red-necked Grebe breeds at inland lakes and ponds in Alaska, across lower western Canada, and northern U.S. from Wisconsin to Washington. They also breed in northern Eurasia, and the global population is estimated at 200,000-300,000. In the fall the RN Grebe migrates south along the west coast, down to central California, and across the Great Lakes to the east coast, where they range down to North Carolina. Although the bird at Las Gallinas seemed content to ignore the many Ring-necked Ducks, Greater Scaups and Canvasbacks in the area, it is know to be an aggressive species, specializing it a sneak attack called the "Sinister Dive". It will approach another bird from underwater like a torpedo then stab at the victim. They have even been know to kill ducks as large as a Northern Pintail, although they are more likely to attack diving ducks. They eat a variety of prey, including fish, crustaceans and insects, all usually swallowed while still underwater. Taxonomy below.

Order: Podicipediformes -  Grebes. Only one family here.

Family: Podicipedidae - The Grebes. 20 species worldwide - 7 in U.S., 6 in California.

Genus: Podiceps - Largest grebe genus, with 8 species worldwide, of which one is threatened (P. taczanowskii, the Junin Grebe). We have 3 Podiceps in the U.S., including Red-necked, Eared and Horned Grebes. Non-U.S. Podiceps grebes besides the Junin are the Great, Great-Crested, Silvery, and Hooded Grebes.

Species: Podiceps grisegena (literally "Gray-cheeked Grebe"). Largest of the Podiceps, and distinctly larger than our Horned and Eared Grebes.

Subspecies: Podiceps grisegena holboellii, a.k.a. "Holboell's Grebe". Holboell is not featured in Mearns book, but I believe the name refers to C. Holboell, a Danish naturalist of the mid-19th century, who studied birds from Greenland, including Redpoll species.

American and Eurasian Wigeon Variations

The American Wigeon male in breeding plumage is a distinctive duck, with a light crown, wide dark stripe on the side of the head extending back from the eye, and a warm flank color.

A close-up front view shows the black line around the base of the bill:

The male Eurasian Wigeon is equally distinctive, with a striking uniform rufous color on the head and lighter gray on the flank, becoming more pink at the shoulder. A small area of green near the eye is sometimes seen and does not indicate a hybrid with the American. Note the absence of a black line where the bill joins the face on the Eurasian Wigeon.

We sometimes see male wigeons that show characteristics of both American and Eurasian Wigeons, likely representing natural hybrids of the 2 species. Sibley and others show that such hybrids are variable. They usually have a two-tone face like the American, but instead of a green iridescence we see a warm brown or rufous color, and variable coloration on the flank. The bill may show a black line at the face.

The male wigeon below shows a rufous brown stripe on the face. He lacks a strong black line where the bill joins the face, and has a mix of gray and rufous on the flank, all suggesting he may have some Eurasian Wigeon DNA:

Here's another shot of the above bird, with an American Wigeon close by for comparison. Alternatively, we may just be viewing an eclipse male American Wigeon that in well along in his pre-alternate molt:

Lastly, sometimes when the light strikes the face at just the right angle we can see a beautiful golden bronze color instead of green, a variation in iridescence and not the expression of brown pigment:

While there is no confusing the male Eurasian Wigeon from the male American Wigeon, the females of these species look quite similar. After consulting multiple sources I came up with this set of criteria that might help in picking out a female Eurasian from a flock of American Wigeons. Now I'd just like to find a female to photograph!

Hooded Merganser - Lophodytes cucullatus

The Hooded Merganser, Lophodytes cucullatus, is one of the last ducks to appear in the fall, and is always a welcome sight. They favor secluded ponds and streams, and are rather shy, so I was pleased to learn that a pair of Hooded Mergansers had returned to the pond just north of the Marin City shopping center, sharing the habitat with a score of American Wigeons. The "hood" refers to the crest, a rather spectacular oversized structure that can be quickly fanned in a startling display, as shown by this male trying perhaps to impress the American Wigeons that were crowding him in a channel off the pond. The female Hooded Merganser paid no attention to the activity.

Male Hooded Merganser swimming with crest retracted

In the next photo the male has started to erect his crest, either to impress the female Hooded Merganser or to intimidate the nearby American Wigeons.

Crest now fanned out to perhaps 60%. Doubt that the female has noticed.

The American Wigeons began to surround the Hooded Merganser, probably because there was simply not much room in this small channel. The birds showed no agonistic behavior, but it seemed that the closer the wigeons got the more the crest became erected.

Crest fully raised. Female merganser no longer close. Pictures are sequential.

Another shot of the male Hooded Merganser with his fanned crest. He's now surrounded by the wigeons, who essentially ignored him. Read more about mergansers below the photo.

The Hooded Merganser is 18" long, a bit smaller than the American Wigeons.

The Hooded Merganser winters here in a variety of freshwater habitats, such as quiet ponds, streams, rivers, and tidal creeks, avoiding marine areas and large open lakes and bays. It is our smallest merganser, and takes more crayfish and insects than it does fish. It's really not very closely related to the other mergansers, and shares an affinity to the Bucephala ducks (Goldeneyes and Bufflehead). In fact the Hooded Merganser and Common Goldeneye are unusual in that they both have the ability to change the shape of their lens (accommodation) to allow them to focus on close objects as they hunt for prey by sight when they dive, virtually always in clear water.

Lophodytes is a monotypic genus, and in fact the word means "crested diver" (Holloway, Dict. of Birds). The Hooded Merganser is the only merganser with a breeding range limited to North America, and there are no subspecies described. World-wide there are only 6 merganser species in all. 4 mergansers are in the genus Mergus (Common, Red-breasted, Scaly-sided, and Brazilian Mergansers), and the Smew, aka White Merganser, is in the monotypic genus of Mergellus.

California Towhee - Pipilo crissalis

Of the 6 Towhee species seen in the U.S. our California Towhee, Piplo cirssalis, is arguably the plainest, but those of us who have it in our backyards enjoy its confiding presence and cheerful if sometimes monotonous loud "pinks". This one was next to the parking lot of the Las Gallinas Ponds. The Cal Towhee is a near endemic species, barely ranging to Oregon and south to Baja.

The side view didn't quite get all of the long tail, mostly because the bird was too close. It was eating the seeds of weedy grass, as seen a closer photo, which shows some of the features that we often miss when viewing with binoculars. 

The last photo, below is simply a crop from the above, to zoom in a bit on the pretty eye and throat. The streaks of the throat are maybe not as prominent as those seen in the Canyon and Abert's Towhee.

Eared Grebe - Podiceps nigricollis

Lots of Eared Grebes right now at the Las Gallinas ponds right now, most of them busy feeding on insects at the water's surface, almost like phalaropes. This shot shows an eye that is more orange than red, perhaps indicating a sub-adult. 

Next shot is a crop to show eye and bill better. Juvenile Eared Grebes have a tan or brown-orange iris, and adults a brighter red. The BNA account (#433) has one photo of similar bird, with a similar eye.The grebe here is not in full basic plumage, as the neck still looks pretty dark, but the dingy neck appearance helps separate it from the similar Eared Grebe, which has a whiter neck in winter. Right now most of the birds are in transition, so it can be confusing. But note the steep forehead with the peak above the eye, definitely "eared". The bill looks more Eared than Horned, but it's not as flat on top as on the average Eared Grebe.

This shot of a juvenile Eared Grebe, taken a few years ago at Bodega Bay, shows the lighter iris and a wash of brown on the grays of the head and back.

Eared Grebes are said to be the most numerous of all grebe species in the world, with a North America population of something like 4 million. They love saline lakes, and stage in huge numbers at the Great Salt Lake and Mono Lake (September to Dec). When gorging on brine shrimp and brine flies at staging areas they are flightless (see below).

I found the account in Birds of North America Online, #433, by Cullen et. al. to be of particular interest in regard to the longs periods of flightlessness in this species, and the dramatic fluctuations in the birds weight and organ sizes, to whit:

"While at fall molting/staging lakes, adults more than double their arrival mass and allow the pectoral muscles to atrophy below a size that allows flight. Then, during a hyperphagic period, they greatly increase the size of the organs involved in digestion and food storage. These changes in size and proportions—the most extreme yet known for any bird—are then reversed during a brief predeparture period, when the birds catabolize much of their just-deposited fat, increase heart size, and reduce digestive organ mass to perhaps 25% of peak in preparation for a nonstop flight to wintering areas. The function of the predeparture events is to reduce wing-loading while maximizing flight range and performance. Migration occurs shortly after food supplies run out, typically in December–January. As a result, the Eared Grebe is the latest of the North American migrants to move to its winter stations. Because a similar atrophy/hypertrophy cycle is repeated 3–6 times each year, the Eared Grebe has the longest flightless period of any volant bird in the world, perhaps totaling 9–10 months over the course of a year. At fall staging areas alone, flightless periods average 3–4 months for adults and may reach 8 months or more in nonbreeders."     (volant = "flying", or capable of flying or gliding)

For an excellent article on sorting out confusing fall Podiceps grebes see:  

Kaufman, K. 1992. The practiced eye: Identifying monochrome Eared Grebes. Am. Birds 46:1187-1190.

Sora - Porzana carolina

Birders who visit fresh water marshes will often hear the strange descending whinny call of the Sora, a small secretive rail that is usually tough to spot. An adult and a juvenile Sora were reported recently at Ellis Creek, Petaluma, at a location where they could be easily found and observed. The adult gave a loud whistled call as it foraged on the west side of pond "D".

Check out those large toes!

First shot shows the large toes typical of many marsh denizens. The yellow bill, is distinctive for the adult Sora. In this case the yellow bill is a bit dusky, which along with the minimal black in the face near the bill suggests it may be a female.

 Second shot gives a better look at the bill, as well as the pretty brown eye. Note the cocked-up tail, a frequent posture. You can just about see the white undertail coverts

Third shot shows it in the grass along the bank of the pond, where is foraged actively for seeds the entire time we watched. Often it was too close for me to frame a shot! By far our best ever look at this shy species.

The Sora is said to be our mostly common and widely distributed member of the rail family (around here I would bet on the Coot to win that distinction). They breed all across Canada in fresh water marshes that have cattails and other emergent vegetation. Most are migratory, despite their not being strong fliers. The genus Porzana has 14 species world-wide, with the other 13 sharing the common name "Crake".