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Wednesday, October 31, 2012

Pirates and marauders


Often a feature on late fall pelagic trips — this is a South Polar Skua (Stercorarius maccormicki).  The common name is meaningful.  This species nests on Antarctic coasts and offshore islands and then makes a clockwise migration around the Pacific Ocean via Japan, across to British Columbia and Washington, then down to California and back to Antarctica!

Here's a view of a different individual from the side.  Most of these photos were taken on 26 October 2012.


Skuas can appear gull-like at first, but note their robust, barrel-chested appearance, the thick neck, prominent hook at the tip of the bill, overall dark coloration, and bold white wing flashes.

If seen well, you may also catch a glimpse of the strongly hooked claws on their webbed feet.  The next photo isn't great, but the claws are quite visible.


Older birds often have light-colored feathers on their napes or hindnecks (they may appear golden).


The white flashes showing on both sides of their wings are due to bold white patches at the bases of the primary feathers.  Three individuals below illustrate how the wing patches look from different angles.




I've wondered about the purpose of these white wing patches.  I read one account that suggested skuas have a spread-wing display during the breeding season.  Perhaps a strong white flash attracts attention or sends some sort of message?


Skuas are known for being "pirates" and "marauders" (see Rich Stallcup's wonderful description of South Polar Skuas in his book, Ocean Birds of the Nearshore Pacific).  They are kleptoparasites, harrassing other birds (e.g., shearwaters or gulls) until they drop or regurgitate their food.  

On fall pelagic trips when gulls are following the boat, it's not uncommon to see a skua heading straight for the flock from very far away.  When within range, they start diving after the gulls (see next photo of a skua chasing an immature gull).


Skuas have an intense aura about them.  Just seeing one gives you the feeling that something serious is going to happen.  They're on a mission; I'm just glad I'm not the one they're focused on!

 

Tuesday, October 30, 2012

Visitors from New Zealand

Pelagic Week #2 continues with one of the most striking shearwaters in our area.


This is a Buller's Shearwater (Puffinus bulleri) photographed offshore near Bodega Canyon on 26 October 2012.

Note the contrasting black and gray markings on the upper surface.  If you trace the black markings starting at one wing tip across the wing and back to the opposite wing tip, it creates a shape resembling the letter "M."

The undersides of the wings are gleaming white, with very narrow black edges.


The next four images were taken last year on 14 October 2011.  They illustrate several other important features of Buller's Shearwaters.

Look for the following: 

- gray bill with black tip
- dark cap and nape (back of neck) contrasting with the gray back
- white throat
- white crescent below the eye (Howell refers to this as a "white teardrop")
- long, wedge-shaped, black tail


Buller's Shearwaters are visitors from the southern hemisphere.  They breed on islands off New Zealand and spend their winter in the North Pacific.  They're most common off north-central California in September and October.

Sometimes large flocks (tens to hundreds of birds) are encountered.  Can you estimate how many birds are in the next photo?  [You can click on the photo to see a slightly larger version.]

( I counted ~122 individuals in the photo above.)

The next image shows Buller's Shearwaters resting on the water in a variety of positions.  Even from a distance the contrasting dark upperparts and bright white underparts stand out.


There's one bird in the photo above that's *not* a Buller's Shearwater.  Can you find it?  This is a little tricky in that some of the Buller's look different because they're in different positions.  But look for a bird that's a little larger, with a dusky gray face, smudgy underparts (not bright white), and a pink bill.

Answer: It's a Pink-footed Shearwater — just below and to the right of center, about three birds up from the bottom of the photo.


Almost every account of Buller's Shearwaters uses the words "graceful" and "bouyant."  A still photograph doesn't do them justice, but perhaps it will inspire you to head out to sea some day to see them in flight!


Monday, October 29, 2012

Soaring with wind and waves


It's hard to take pictures of soaring birds while on a boat in rough seas.  But here are a few shots of a Flesh-footed Shearwater (Puffinus carneipes) near Bodega Canyon on 26 October 2012.

Don't pay too much attention to the common name.  Although they have pinkish-colored feet, the feet are not often visible in flight.

Look for the overall dark brown coloration on both the upper and lower surfaces.  And note how the pink bill (with gray/black tip) contrasts with the very dark head.

More subtle field marks include the relatively large overall size (wingspan of ~40 inches) and the relatively broad wings when compared with other local shearwaters.


Although the flight feathers can appear silvery in some light, it's still a much darker bird than a Sooty Shearwater that shows strong white wing linings.  Sooty Shearwaters also have a much thinner and uniformly dark bill.

The wings of Flesh-footed Shearwaters can look narrower at some angles (see below).  But again, note the contrast between the dark head and the pink bill.


Flesh-footed Shearwaters are regular but rare to uncommon visitors to our region.  They are trans-equatorial migrants — birds that breed on islands off Australia and New Zealand spend the non-breeding season in the North Pacific.  Most records at Bodega Canyon/Cordell Bank are between September and November, when the birds are probably making the journey back to the southern hemisphere.

You may see hundreds of individuals of other species of shearwaters on an offshore boat trip, but you'll be lucky to spot one or two Flesh-footed Shearwaters. 

Here's another view of the same bird silhouetted against the sky.  There's something awe-inspiring about the design of seabirds and how well suited they are to spending most of their lives soaring with wind and waves.

 

Saturday, October 27, 2012

A lesson in light


One of the highlights from a boat trip to Bodega Canyon and Cordell Bank on 26 October 2012 was a Manx Shearwater (Puffinus puffinus).

The Birds of Sonoma County California lists two records for Manx Shearwater: the first at Bodega Canyon on 7 April 2008 and the second on the way to Cordell Bank on 16 November 2008.  I don't know if there have been other records since then, but this is currently a rare species in county waters.  We encountered it fairly close to Bodega Head.

There are several important field marks to look for:  the most critical is the color of the undertail coverts (feathers under the tail).  In the photo above, note that they're white almost to the tip of the tail.

In addition, notice the following:

- overall small size (wingspan of 75-84 cm, or 30-33 inches)
- strong black and white coloration (see black upperparts in next photo)
- an almost hooded appearance due to a white "hook" or "notch" extending upward behind the face
- a mostly pale unmarked underwing, with a narrow black border 
- gray underside of primaries (at wing tips)
- relatively short tail




The next photo shows the white "saddles" just in front of the black "thigh patch."


The image below is the same individual, but in different light and at a slightly different angle.  Note that with a quick view, it appears that the undertail coverts could be dark.  This is a lesson in light.  It was important to continue watching the bird until there was a clear view of the undertail coverts in good light.  Otherwise, this bird might have been mistaken for a Black-vented Shearwater.  [Note that Black-vented Shearwaters have dark undertail coverts, appear brown above rather than black, have a diffuse and dusky face pattern, and lack the white saddles.]


Until the last 20 years or so, Manx Shearwaters were considered rare throughout the Pacific Ocean.  They were first detected in California in the mid-1970s, and the first formally accepted record was from Monterey Bay in 1993.  There are now annual records in California (most between the Farallon Islands and San Luis Obispo County).  Late summer and fall (especially September and October) is the most likely time to see them.

Although primarily an Atlantic species (the common name means "from the Isle of Mann," located in the northeast Atlantic), Manx Shearwaters are now potentially breeding on Triangle Island off Vancouver Island and on Middleton Island in Alaska.  We may see more of them in the future!

(Facts from Rare Birds of California and Petrels, Albatrosses, and Storm-Petrels of North America by Steve Howell.)


Friday, October 26, 2012

Bow riding

Ready for Pelagic Week #2?  During the next week I'll be highlighting sightings from a boat trip to Bodega Canyon and Cordell Bank on 26 October 2012.  Here's a chance to meet your offshore neighbors!


Northern Right Whale Dolphins (Lissodelphis borealis) are challenging to photograph.  They streak through the water and leap into the air at unpredictable moments.  Today a few decided to ride the bow waves of the boat.

Remember that right whale dolphins lack dorsal fins, so their backs are extremely smooth.


If you look closely at these pictures, you can see the small, curved pectoral fins held out to the side.  These fins are used for steering (the flukes, not visible in these photographs, are used for propulsion).
 

Here's a view of an animal under water.


A couple of new facts I learned about right whale dolphins (thanks to the Mammalian Species account by Jefferson and Newcomer and the Field Guide to Marine Mammals of the Pacific Coast by Allen, Mortenson, and Webb) :
  • Females give birth every 2 to 3 years
  • In the North Pacific, calves are born during summer 
  • Calves are not black like adults, but instead have brown/gray/cream coloration; they become black by the end of their first year
  • When born, the calves are estimated to be ~80-100 cm in length

For more information about Northern Right Whale Dolphins (Lissodelphis borealis), review the post from early September.

Thursday, October 25, 2012

Portait of a predator


Adult Peregrine Falcon (Falco peregrinus) perched on the outer coast of Bodega Head on 25 October 2012.  (Adults are slate gray, juveniles are brown.)

Although they eat a wide variety of prey, Peregrine Falcons used to be called Duck Hawks.  Can you find the duck wing in the photo below?


From the emerald green in the wing, it appears this falcon was feeding on a Green-winged Teal.

After it was done feeding, the Peregrine spent some time preening.


Whenever a raven flew over, she watched carefully.  (The large size indicates a possible female.)


She stretched her wings and spread her tail before take-off.  I think this is the best view I've ever had of a Peregrine Falcon's tail!

 

Wednesday, October 24, 2012

Sage Thrasher!


I was a little more than surprised when I spotted this bird on the way through the BML (Bodega Marine Laboratory) parking lot at the end of the day on 23 September 2012.  I looked at it and realized that I wasn't quite sure what species it was!

It flew off into the depths of a shrub, but thankfully started to call which made it easier to find again.  The most common call note was a clear whistle, which I've seen written as wheurr or whee-er.  It also occasionally gave a chuck note, somewhat similar to that of a Hermit Thrush.

Luckily, it perched on the edge of a shrub just long enough for a few more photographs.


Above, note the overall brown/gray coloration (with some dark feather centers), streaks above and below, pale yellow eye, and two narrow white wing bars. 

In the next photo you can see the relatively short and uncurved bill, mostly black with a pale base.


With a head-on view, note the dark stripes along the sides of the throat.


Although not visible in these photographs, the tail when spread had white corners (reminiscent of an American Robin).

This is a Sage Thrasher (Oreoscoptes montanus), formerly called a Mountain Mockingbird.  They're casual fall vagrants to the coast, this being only the third record for Sonoma County!  The last record was from 14 years ago on Bodega Head on 21 September 1998.  The first was observed near Petaluma on 27 September 1986.

Sage Thrashers are the smallest of the thrashers.  Although the westernmost breeding areas are in eastern California (associated with sagebrush), they're known for wandering during migration.

P.S.  Thanks to many local and non-local birders for helping to confirm this identification!

Tuesday, October 23, 2012

Sky and water


Mixed shorebird flock, primarily Dunlin (Calidris alpina) and Sanderlings (Calidris alba).  

Salmon Creek Beach, 20 October 2012

This image started to remind me of M.C. Escher's woodcut called Sky and Water I.

Monday, October 22, 2012

Giant!


In previous posts, I've mentioned the Ochre Seastar (Pisaster ochraceus) and Short-spined Seastar (Pisaster brevispinus).  The other seastar in this genus found in the Bodega Head region is the Giant Seastar (Pisaster giganteus).

The species name, giganteus, refers to the size.  Each ray or arm of this seastar can be more than 30 cm (12 inches) long!  The individual in this photo measured >70 cm (27.5 inches) across from tip to tip!
  

Compared to the more common Ochre Seastar, the spines of the Giant Seastar are less numerous, longer, and more uniformly distributed across the upper surface (rather than being clustered or forming patterns).  The spines may be white, pink, violet, or blue. There is often a blue ring around the base of each spine (not as visible in these images).


 All of these photos were taken at the Spud Point Marina in June 2008.


For some reason, students have a tendency to put seastars on their heads.

I'm wondering if Chris had the same expression on his face tonight when the Giants won Game 7?  

A giant win for San Francisco!

Sunday, October 21, 2012

Stiff winds and stiff wings

Yesterday it was blowing 20-25 knots out of the northwest, with gusts to 30-35 knots.  I'm guessing the strong winds had something to do with this visitor to Salmon Creek Beach.  Do you recognize this bird?


Here are a few closer views:



Note the relatively stocky and thick-necked appearance.


This is a Northern Fulmar (Fulmarus glacialis).  Fulmars are seabirds related to shearwaters and petrels.  They're in a group known as "tubenoses" because their nostrils are enclosed in long tubes on top of their bills.  This feature is hard to discern in the pictures from 20 October 2012, but see the next close-up taken at Cordell Bank on 14 October 2011.


In all of these photos, note the stiff-winged profile and imagine a flight pattern alternating between glides and shallow wing beats.  The fulmar was soaring up over the waves, moving across the wind.  


The distinctive arcing and banking flight caught my eye.  Although I've seen fulmars from land, this is the first one I've noticed spending significant time in the surf zone.  


During the fall and winter, it's common to see fulmars offshore, with an ocean backdrop.  It's unusual to view them with coastal hills and trees in the background, or gliding over driftwood on the beach!



A few fun facts about Northern Fulmars (thanks to The Birds of North America account by Hatch and Nettleship):

- There are only 34 breeding colonies in North America.  Half of them are in Alaska.  99% of the Alaskan population is found at several island colonies (Semidi Island, Chagulak Island, Pribilof Islands, and St. Matthew and Hall islands).

- Fulmars are broadly distributed across the Pacific Ocean during the winter, but common only north of 35-40°N.  (Bodega Head is at 38°N.)

- They don't breed until 8-10 years old.  They raise only one chick per year.  They're very long-lived, with an average lifespan of ~30 years.

- Fulmars have a strong sense of smell and use olfactory cues to locate their prey, e.g., fish, squid, and zooplankton (primarily crustaceans).