EA 110 – Field Ornithology – Class 6

Wednesday was another great class in the continuing field ornithology class I’m taking. It’s hard to believe that next week is the last class of this session (but the next set of 7 classes starts the following week, and I do plan on continuing to take this class indefinitely, or until we finish the book, whichever comes first).

Red-tailed Hawk at Point Reyes on last weekend’s field trip

We started with a recap of last weekend’s field trip to Point Reyes (more on that later). 9 species were added to the cumulative list of birds seen there on this date for the past 20’ish years. Those birds were:

Canada Goose

• hard to believe, but, the common Canada Goose wasn’t seen on any previous class trip to this area
• Joe was waffling on if these particular geese were the “Taverner’s” Cackling Goose subspecies or the “Lesser” Canada Goose, as they look extremely similar. He finally settled on Lesser Canada Goose.

Swainson’s Hawk

• quite a rarity, and the best bird we saw all day. When I entered it into eBird, I was later contacted by their database people and asked to provide details on the sighting before they’d accept the sighting into their full databse

Rock Pigeon

• must have been omitted from the list due to clerical error 🙂

Eurasian Collared-Dove

• the American population are descendants of escapees from a bird dealer in the Bahamas, which subsequently established a colony in Florida, and have been expanding their range quite rapidly. Comparing the older range map for this bird in Sibley with the new one in the National Geographic Guide, it’s obvious this bird will soon be seen everywhere in the US.

Warbling Vireo

• breed in oak woodlands and are more often seen in the interior than in the Bay Area

Western Scrub-Jay

• this non-migratory bird has been observed nesting at Drake’s Beach, where we saw a pair of them, in previous years

Violet-Green Swallow

• this was the only one of the many swallows we saw that was close enough to identify

Wrentit

• we heard, but did not see, this bird, which has also been seen nesting near Drake’s Beach Visitor’s Center

Common Yellowthroat

• quite probably another clerical omission from the cumulative list

We picked up on pg. 176 of the National Geographic Field Guide to North American Birds with “Rockpipers.”

“Rockpiper” is the collective name for shorebirds that prefer rocky habitat, including Turnstones, Black Oystercatchers, Tattlers, Surfbirds, and Rock and Purple Sandpipers.  Unlike, say, Snowy Plovers, most rockpipers are not too sensitive to habitat disturbance (not least because people don’t usually let their dogs run off-leash on rocks, where rockpipers are found, unlike beachers, where Snowy Plovers are/used to be found).

Ruddy Turnstone (RUTU):

• breeds on Arctic coasts in both hemispheres, and is found coastally worldwide.
• has a slightly upturned chisel-shaped bill, like all Turnstones, and prefers beaches and rocky shores
• has short bright red legs in alternate plumage and orange legs in basic plumage
• has declined over the past 10-15 years in California, and used to be seen in Black Turnstone flocks
• Christmas Bird Count data shows clearly that RUTU has been declining since the ’70s.
• data also suggest that they were never a common bird on the west coast, and that the numbers seen in the 1960s and 70s were abnormally large.
• they have black “loops” on the side of their breast with white centers, and the white on their chest comes up to a point, unlike Black Turnstone, which has a straight line of contrast between their white bellies and black heads

Black Turnstone (BLTU):

 
Black Turnstone at Sutro Baths in San Francisco

• is only found on the west coast of the US
• is the most common Rockpiper in California
• their brownish legs compared to the RUTU’s red or orange legs, is a good field mark if in doubt
• in alternate plumage, have a white eyebrow, white at the base of the bill, and faint white spotting on the sidesof their breast
• are a dark chocolate brown on top
• their whole breast is dark, unlike the white center on a basic-plumaged RUTU
• in flight, have a bicolored tail, 2 bold white wing stripes, and white on their back (same as RUTU in flight)
• underwings are all-white, and they appear hooded from below

Surfbird (SURF):

 
Surfbird at Sutro Baths, San Francisco

•  is an Alaskan breeder on remote mountain ridges and mountain tops in tundra
• winters along the California coast
• is somewhat regular and common here in winter
• is best seen either at low tide when they forage, or at high tide when they gather in roosts
• numbers appear to have declined recently
• alternate plumage is cryptic, with buffy scapulars
• bill has a pale-based mandible and is short and stubby for a sandpiper
• alternate plumage has more and darker chevron-shaped markings on the chest than basic plumage
• legs are always a straw-colored yellow, and are short
• are uncommon on the shores of the San Francisco Bay itself
• heavily spotted in alternate plumage, solid’ish gray in basic plumage
• have a plump appearance
• in winter, can be confused with Wandering Tattler.  SURF has chevrons on its chest, and is patterned in flight, while Wandering Tattler looks more streamlined vs. plump

Rock Sandpiper (ROSA):

• if present in a mixed flock of SURF, it’s the last one to fly when a wave hits the group
• has 3 subspecies
• is about the size of a Dunlin or Sanderling, smaller than Turnstones
• the ptilocnemis subspecies is distinct, with a buffy chest and dark breast spot
• are easiest to see in the Pribilofs in Alaska
• are very dark above, white underneath
• look like a small, dark Surfbird, but with a long, drooping bill
• has a white wing stripe, wider than that of  a Purple Sandpiper
• tail edges are white, center is black, like other Calidris sandpipers
• an outstanding question is why is the Pribilof ssp. of Rock Sandpiper, when the Aleutian ssp. of Rock Sandpiper and the Purple Sandpiper are much more similar to each other than the Pribilof and Aleutian ssps. of Rock Sandpiper are?
• juvenile ROSA are never seen south of the breeding grounds
• all have a black chest patch in alternate plumage
• is a rare bird in the SF area, mostly occurring north of here, but when they are found, the same individuals are seen in the same place at the same time of year, year after year
• they have been seen as far south as Los Angeles

Purple Sandpiper (PUSA):

• replaces the Rock Sandpiper on the East Coast
• there are no West Coast records (but it’d be hard to tell since any would likely be assumed to be Rock Sandpipers).
• one reason for the split between ROSA & PUSA is that PUSA lack ROSA’s dark chest patch in alternate plumage
• looks identical to ROSA in basic plumage, but is only found on the Atlantic coast
• there are no known ROSA records on the east coast, nor PUSA records on the west

We concluded with our usual quiz, which I didn’t do very well on, confusing my Long-billed Curlews and Whimbrels.  I got 13 out of 20 correct.

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