Black-crowned Night-Heron

Recent low low tides during the day were better for tide-pooling than birding, but Don and I nonetheless decided to check out Bodega Bay in the hope of finding a few late-departing shorebirds. As we drove along the road at Doran Beach we noted mats of algae and eelgrass on the mud flats, hosting about a dozen Western Gulls. We saw one of the gulls pick up a small flatfish (sand dab type) that apparently has gotten trapped in the eelgrass. We then noticed that 2 of the "gulls" were actually Black-crowned Night-Herons, foraging for any crabs or other prey. We're used to seeing Night-Herons on day-roosts, so it was fun to watch them actively hunting for a change.

The BC Night-Heron is a study in blacks, grays and whites, requiring underexposure to capture the range of shades. The large deep orange eye is valuable for hunting in the near-dark, and the short yellow legs add a nice color accent. When roosting their necks are retracted, resulting in a kind of skulking posture (Rich always said they looked "grumpy"). But when hunting, as here, the neck is more extended. The white plume (sometimes 2-3 feathers extending back from the hind-crown) is present in both sexes.

In the last shot the bird is facing into a stiff breeze, so the plume has extends back in a straight line.

"Nycticorax" translates as "Night Raven", a name chosen because its harsh call is vaguely similar to that of the raven. The species is distributed widely in the world, in both fresh and salt-water marshes.

Indigo Bunting, Savannah Sparrow and Common Buckeye at Loma Alta

One of my favorite spring walks in hereabouts is the Marin Open Space walk up Loma Alta, heading south from Big Rock, along Lucas Valley Road. The area has good shows of spring wildflowers (best today was a Calochortus leuteus (Gold Nuggets), and this time of year some popular breeding birds have returned, including Lazuli Bunting, Lark Sparrow, Grasshopper and Savannah Sparrows. Today I followed a bright Savannah Sparrow foraging along the roadside (it's a fire road trail). While photographing it I heard an insect like call that may have been a Grasshopper Sparrow, a species often seen here. The Savannah here shows an average amount of yellow above the eyes  for western birds.

Further along I spotted a Common Buckeye (butterfly) and watched it land in a moist sheltered area, perhaps to escape the 20-25 mph winds. Sad that this striking creature lives only about 10 days as an adult (Bob Stewart, "Common Butterflies of California"). The good news is that this little beauty is very common, and seen throughout the United States.

Near the "top", about a mile from the start, I looked for a recently reported Indigo Bunting,  in an area just north of the seep that drains onto the roadway. The reported sighting was near a blooming Elderberry tree on the downhill (left) side of the trail. While there I heard a bunting calling from the upslope, and located a male Indigo Bunting high in a bay tree. The wind was so strong, and the bird was so will "hidden" that I almost didn't venture a shot, but "nothing ventured ….".

The result is what we call a record shot, sufficient to document the event but not something to crow about. But it's not every year we get to see this more eastern bunting. The Indigo Bunting is listed as "rare and regular" in California, with even rarer documentation of attempts at breeding, sometimes with a Lazuli Bunting. The Lazuli is a more western bird, and in areas where they overlap in spring they sometimes interbreed, with most attempts proving unsuccessful.

Common Loon, aka Black-billed Loon or Great Northern Diver

Recently we spent 2 windblown hours birding at Bodega Bay, Sonoma County, CA. There a good number of birds gathered in the cove between Puerto Bodega and Spud Point, mostly massing close to the shoreline in the lee of the roadbed and riprap. Best of the bunch was an adult Common Loon in alternate (breeding) plumage, floating quietly. The loon never dove, extended its neck or spread its wings, but still provided good viewing for some digiscoped photos. Other species in the flotilla included Western and Clark's Grebes, Greater Scaups, Ruddy Ducks and 2 basic plumage Red-throated Loons.

Palmer (Handbook of North American Birds, Vol. 1 - Loons through Flamingos) reported the older common names for Common Loon as "Black-billed Loon" and "Great Northern Diver". The Common Loon is very similar in appearance to the slightly larger Yellow-billed Loon, Gavia adamsii, so the adjective Black-billed seems more appropriate than Common. "Common" tells us little as to how the species sets itself apart from the other 4 loon species, and especially from the Yellow-billed. "Common" can apparently refer to relative abundance compared to other local loon species, or to "common to both western and eastern hemispheres."

The photos show most of the important field marks of the Common Loon, especially the big blocky black head,  the huge deep black bill and the attractive checkered pattern of spots on the back (scapular feathers). In this loafing bird with retracted neck we can't really appreciate the shape of the neck collar, which widens toward the back of the neck (Yellow-billed's collar is widest on the side), and we can barely seen the small collar on the front of the neck below the chin, seen only as a few white spots. This photo also shows clearly how the collar tapers toward the front, and is incomplete, sort of like the breast band of the Snowy Plover.

The second photo shows the loon swimming just in front of a group of Greater Scaups, suggesting an impressive size. The Common Loon is indeed a big bird. The average length is about 32", with a surprising range of 24-39", quite unusual for a single species. The weight average is 9 pounds, with a range of 3.5 to 17.6 pounds! The heavy body helps with diving, and in fact some of the bones are solid, which is unusual for a migratory bird. The molt pattern is also unusual, in that all the flight feather are replaced during a flightless 6 week period, primaries and secondaries at the same time (synchronously), occurring in spring just before migration. The heavy weight of the loon requires a near full complement of flight feathers, which probably explains the unusual molt strategy. The species breeds all across Canada, and in some of our northernmost states. Historically the breeding range extended further south, and included Northern California. They are long-lived, and lay only 2 eggs each year.

You'd think the heavy birds would have trouble in the air, but in fact they are strong fliers and speed along at 75 mph during migration. The adults have few predators, aside from the occasional Sea Otter or Bald Eagle.

The 3rd photo (5943) shows how a black bill can appear silvery in certain light (same can happen with the glossy feathers and bills of ravens and crows). Again note the red iris, as well as hints of color on the head and neck. 

One last photo shows the red eye and the rear-mounted feet. The breeding plumage adults will leave soon, but here we always have some over-summering Common Loons, which are probably subadults or unhealthy birds. They can breed at 2 years of age, but it can take 3-4 years to attain full adult alternate plumage.

And that's what I learned in school today.

Brown-headed Cowbird - Molothrus ater

The Brown-headed Cowbird, probably better named Bisonbird, was a bird of the open grasslands where it followed the buffalo herds. As woodlands were cleared in the eastern half of the U.S. the cowbirds were able to extend their range, which now excompasses all of the lower 48 and a good part of Canada and Mexico. Cowbirds are well known as nest parasites, the female laying up to 30 eggs a year in the nests of other birds, often of one particular species for a given female cowbird, but the list of affected songbirds exceeds 200 species. Of greatest concern are species with very limited populations, such as Kirtland's Warbler and Black-capped Vireo, which could disappear if local cowbirds proliferate.

Overall the Brown-head Cowbird population is reasonable stable now. They are protected by the migratory bird act, so local control efforts require a special permit. Some common species often hosting cowbird chicks include Red-winged Blackbirds, Song and Chipping Sparrows, and both Eastern and Spotted Towhees. Some authorities say the female BH Cowbird is under-rated as a parent, as it chooses the nest to raid carefully, and returns to check on the status of the egg and later on the chick, even in some cases bringing food. Cowbirds are promiscuous, so both males and females may have multiple partners in a given breeding season. Good source of information is Cornell Lab's "All About Birds":

http://www.allaboutbirds.org/guide/Brown-headed_Cowbird/id

Note the typical blackbird bill (yes, the cowbirds are in the blackbird family, Icteridae), which can appear silvery when the light hits at a certain angle, as well as the dark iris. The Bronzed Cowbird, invading in the southwest, lacks a brown head and has a red iris.

Black Skimmer - Rhynchops niger

These photos from Florida trip in February, Fred Howard Park, Tarpon Springs. I think they show a male Skimmer, because of the gap in the bill. The deep black suggests alternate plumage. The frontal shot show the laterally compressed bill, which enables it to slice through the water with minimal resistance. 

Side view shows the long wings (span 44") and short red-orange legs, and of course that amazing underbite:

Last shot gives us a closer look at the bill. Skimmers fly very close to the water, dipping the lower mandible into the water's surface and snapping it shut when they contact a fish. Fun to watch.

Skimmers are seen on both coasts. In California their northern range limit is the SF Bay Area. Once year we had one loafing at Shorebird Marsh in Corte Madera, Marin County. They are seen regularly at preserves in the south bay, and are known to breed there.

The Black Skimmer, Rhynchops niger, displays great size differences between male and female, with the larger male fully 10% bigger or more in all measurements, and fully 30% heavier (365 gm. vs 265 gm., or 12.9 oz. vs 9.3 oz.). The male has a bowed or "open" bill (BNA account).

Skimmer taxonomy tends to vary with the source, and remains unresolved. What follows is the mostly widely accepted understanding, and to me the most sensible.

Order: Charadriiformes - Huge and diverse order, including shorebirds, gulls, auks, etc.

Family: Laridae - Gulls, Terns, and Skimmers. (Skuas and Jaegers now have their own family)

Subfamily: Rhynchopinae - The Skimmers. Only one genus here. The other sub-families in Laridae are Larinae (Gulls and Kittiwakes) and Sterninae (Terns and Noddies). Skimmers thought to be closer to the terns, but really not very close.

Genus: Rhynchops - Skimmers. 3 species world-wide. Other two are the African Skimmer (yellow tip on bill, and not dimorphic) and the  Indian Skimmer (always with white collar, and orange-yellow on bill).

Species: Rhyncops niger - Black Skimmer. 3 subspecies, all in the New World. Ours in North America is the nominate subspecies, R. n. niger, which is mostly coastal, but seen inland in Florida and California (especially at the Salton Sea). Subspecies further south are more riverine in their nesting and foraging.

Skimmer population in NA is fairly stable, but nesting success in not high (less than 50%), with disruption by flooding, predation and human disturbance. Caution advised in banding or observing nesting colonies (duh). 

Barrow's Goldeneye

At Lake Solano Park (just below where Pleasant's Valley Rd. joins Route 128), the viewing is usually good for a good variety of river ducks, and on Feb. 5 we spotted many Common Goldeneyes and a few Barrow's, both male and female, foraging in mid-stream opposite the picnic area.

The male Barrow's Goldeneye is unmistakeable, with a large white crescent on the face plus other clear diagnostic marks. The female Goldeneyes can present more of a challenge. The Barrow's female's bill is usually all orange, shorter than that of the Common Goldeneye, and "deeper" at the base, giving the bill a stubby appearance. The Common's longer bill has a different shape, which I'm still trying to get used to. When viewing a group of 3 ducks (above) at 25-30 yards, we could easily discern that one was an adult male Barrow's, and a second was an adult female Barrow's. We kind of assumed that the other female Goldeneye, with orange mainly at the distal part of the bill, must be a Common Goldeneye female. On returning home I checked the photos, and began to wonder about the puzzling female with the half orange bill, whether it was a Common or Barrow's female.

Photo 2 shows the Barrow's male with the puzzling female:

Photos 3 below shows Barrow's male and female swimming together. Of note there were Common Goldeneyes pretty close by, although these 3 keep pretty much to themselves. There were no significant courtship displays taking place.

Don't know what to make of the fact that the male's iris is the typical bright yellow, or almost yellow-orange, whereas the iris of the females here has a greenish cast to the yellow.

The guide books are somewhat limited in what they can teach about differentiating similar looking species, so I needed more information. Sibley provided just what was needed in this article from his website: http://www.sibleyguides.com/2010/01/distinguishing-female-barrows-and-common-goldeneyes/

After reviewing Sibley's article on the Sibley Guides website, I realize that such ID challenges are far from straightforward. It seems one pretty much has to disregard head shape for clues, at least regarding birds that are actively feeding, which is often the case with the Goldeneyes I see. The feathers of the head are lowered before a dive, so the profile dramatically changes and the steep forehead disappears. Same thing happens with Eared Grebes, which can have the profile of a Horned Grebe when foraging, i.e. the "steep forehead" becomes shallow, and the forward peak on the crown is lost.

Here's a very unscientific collage of some of my female Goldeneye photos, with those from Lake Solano at the top:

Top left is a typical Barrow's female, with an all orange bill that is thick at the base and a bit "stubby". The bill features a gentle curve of the lower mandible that make it almost look up-turned. The next 2 shots in the top row are of the puzzling female shown earlier above, showing what I think is a more stubby (shorter) bill than seen on the Common Goldeneyes in the row below. In the top row note the gentle curve of the lower edge of the bill, the deep/thick base, and more extensive orange than we see on the Common GE's bill. In all 3 shots we see a pretty good black "nail" at the tip of the bill.

The bottom row in the composite shows 3 female Common Goldeneyes. Note the relatively straight line along the bottom of the bill from base to tip, which can vary a bit depending on the angle of view. The orange at the tip is confined to the distal 1/3 of the bill, and the border is a clean diagonal line. The bill seems less deep at the base, seems relatively longer (less stubby), and has a small black nail at the tip. Note the great variation in head shapes among the 6 photos. Common Goldeneye females can indeed show more orange in the bill, but rarely, especially on the west coast.

Bottom line is that the consensus of "Barrow's" for the puzzling female seems to be a reasonable ID. For me the lesson is to focus on the bill. Weigh other features like head shape only if a careful comparative study can be made of birds in similar postures, such as Sibley did in Oakland some years ago. Likely he was at favorite spot for Barrow's, where Lake Merritt flows out though Laney College (area currently being restored), where the birds could be studied at close quarters.

Another lesson perhaps is to beware of any given selection of photos that are meant to prove a point, as selection bias severely limits any conclusions that can be drawn.

Reddish Egret - Egretta rufescens

Experienced birders know that you not only have to go to the "right" places to find certain birds, but you have to go at the right time. For the Reddish Egret that means going to areas that have broad open tidal flats, and going at low tide, as Reddish Egret hunts for small fish in shallow (2-6") water. Well, during our visit the low tides were rather high, i.e. high lows, and we saw just one Reddish Egret, and only briefly at that. The good news was that the bird was close and the light was good.

The plumage of the adult dark morph Reddish Egret changes little with breeding season, which can be vary in timing. The most dramatic changes are in the bare parts, as shown in the first photo. The legs become blue, the base of the bill becomes brighter pink with a jet black tip, and the lores blaze with stunning blues and violets. It doesn't get much better. Add to that the varied and sometimes frenetic foraging behavior, and you've got a memorable sighting.

Second photo was taken when the bird got too close (30'), and shows the spread wings often seen when its hunting, along with some of the fine plumes of the back and the impressive shaggy neck feathers.

A reflected image of the subject can add interest to a photo, or not, but this is the first time for me where the reflection was more in the nature of a shadow, which I thought was pretty cool. The bird is back-lit in all 3 photos.

The Reddish Egret population, decimated by the plume hunters, has made a decent recovery in most areas. It is pretty strictly a coastal species, and prefers warm salt water. Eagles can be a significant predator of both chicks and adults, and that may mean trouble in Florida where the Bald Eagles are successfully breeding in greater numbers. Raccoons can also disturb nesting colonies, and fire ants add to the threats.

Reddish Egret in seen in Florida, the Gulf Coast states, Baja, both coasts of Mexico, and further south on tidal flats of Costa Rica, Belize, various West Indies islands, and even the north coast of Venezuela. 

Population:

"As an inhabitant almost exclusively of coastal lagoons of the Gulf Coast states, the Reddish Egret is North America’s rarest and least known ardeid. This species was nearly extirpated from the United States by plume hunters prior to 1900. Since then, populations have recovered, and U.S. populations currently total about 2,000 pairs; less is known about numbers in Mexico or the Caribbean." (BNA Online, #633, Lowther and Richard, 2002)

On color change in bare parts:

http://www.saaudubon.org/articles/SoftPartColoration.html