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Tuesday, January 31, 2012

Missing rainbows

Today I found myself missing rainbows.  During the winter, Bodega Head is usually an excellent place to see these beautiful optical displays.  However, with the lack of precipitation this winter, a lack of rainbows has followed.

Here are two photos, the first from 13 February 2009 and the second from 30 March 2010.  One was taken in the morning and the other in the afternoon.  Can you guess which is which?



The first photo was taken in the morning (rainbow over the ocean to the west, sun behind to the east) and the second was taken in the afternoon (rainbow to the east, sun to the west).

Note that most primary rainbows show Newton's color spectrum from top to bottom: Red, Orange, Yellow, Green, Blue, Indigo, Violet (you may have memorized this sequence as ROYGBIV).

Supernumerary rainbows don't follow this sequence.  They are color bands inside the arc of the primary rainbow, often in a paler green or purple.  You can see a few below the Violet band in the dune rainbow (above) or in this close-up of the same rainbow.


There's still a lot of winter left, so cross your fingers for a few rainbow days!

Monday, January 30, 2012

Feathers and feet

On 29 January 2012, Eric encountered a bird kill along the side of the trail.  It must have been pretty recent, as most of the bird was still visible.  Below are pictures of the wings and feet.  Can you guess the species?

 Above, note the sparse feathering extending all the way to the talons!

Above, a vole's perspective.


Ready for the answer?  Here's one more clue (below).  Note that the leading edge of the outermost primary (flight feather) is distinctly fringed.  This trait is characteristic of one group of hunting birds.  The fringe is involved in allowing the birds to fly silently, breaking up the air as it flows across the front of the wing.


These are the feathers and feet of a Barn Owl (Tyto alba).  Evidence at the scene suggests that it might have been eaten by a Great Horned Owl.  Six species of owls have been documented on Bodega Head.  [We haven't been graced with the presence of a Snowy Owl this winter, as has much of the rest of the country, but it's always worth hoping!]

Sunday, January 29, 2012

Early wildflowers

Growing up in New England, it's still a little hard for me to believe that "spring" wildflowers start blooming in January in California.  The climate here is completely different of course, with a wet season from October-April and a dry season from May-September.  

Many plants start to germinate when the rains begin in October/November, and the earliest flowers appear a few months later in January/February.  Here are three species that started flowering during the past week:


Footsteps-of-spring, or yellow mats (Sanicula arctopoides)
[Sometimes called bear's-foot sanicle]


Baby blue-eyes (Nemophila menziesii)
[Named after Archibald Menzies]


Bitter-cress (Cardamine oligosperma)
[Note the developing seed pods, called siliques]

Saturday, January 28, 2012

Harlan's Hawk?

Today an unusual hawk appeared overhead while I was watching shorebirds in Bodega Harbor (on the inside of Doran Beach).  It was soaring on thermals with Turkey Vultures.  

At this point I'm leaning towards calling it a "Harlan's Hawk" — a very dark subspecies (used to be considered a full species) of Red-tailed Hawk.  There are only two records for Harlan's Hawk listed in The Birds of Sonoma County, so this is an uncommon bird in this area.  They're more common in Alaska/BC. 

Here are a few photos of this striking raptor (apologies for the lack of sharpness, the hawk was far away).  See what you think, and let me know if you have feedback about its identity!

 Possible Harlan's Hawk in lower left, Turkey Vulture in upper right (carrying food!).

Friday, January 27, 2012

Wintering warblers

A few people have asked me recently about small birds with yellow at the base of their tails, flitting around in shrubs.  They're most likely Yellow-rumped Warblers, one of the most common warblers in North America.  (Although it's an appropriate name, I also like one of the older names for this species, Myrtle Warbler, as it reveals some of their ecology.)

During the winter they often feed on Wax Myrtle fruit (see photos), as well as insects and other invertebrates.  These photos were taken at the north end of Bodega Harbor (near Whaleship Road).


Thursday, January 26, 2012

Beach scavengers

It's common to see Turkey Vultures and Common Ravens cruising Salmon Creek Beach, searching for potential food items.  

On 24 January, this vulture discovered a loon that had just washed ashore.  It appeared to be trying to pull it above the swash zone.  Vultures are scavengers, feeding on carrion.  Their genus name, Cathartes, means "purifier".


This raven may have been feeding before I encountered it.  It jumped up onto the driftwood, walked along, and then swiped its bill from side to side on the end of the log (perhaps to clean it).

 

It's always interesting to see what the waves wash in, and intriguing to note what attracts the gastronomic attention of these beach scavengers.

Wednesday, January 25, 2012

Soft corals on Bodega Head

When many people think of corals, they often imagine a subtidal reef in calm, tropical seas.  But at least seven species of soft corals can be found in the surf-pounded rocky intertidal zone along the California coast.  They're small and inconspicuous, and not much is known about their biology.  

Several species of octocorals have been documented on Bodega Head.  As you can surmise, the polyps have eight tentacles.  The tentacles are pinnate — feather-like, or with similar parts aligned on opposite sides of a common axis.

Some of you might remember the post on 12 January about sponges.  When Eric looked more closely at this cluster, he spotted a few soft coral polyps next to the sponges!

At first we thought this might have been Clavularia, but Jeff Goddard (who has more experience with this special group of invertebrates) thinks it's Cryptophyton goddardi, so we'll go with that.  I've been searching for a soft coral on Bodega Head for years, so I was particularly excited to finally see them!

Here are two expanded polyps, as well as a cluster and a single contracted polyp.  When open, they measure ~3-4 mm from tip to tip.  Look for the mouth inside the circle of tentacles.


 

P.S.  We'll talk about stony corals and hydrocorals in future posts!

Tuesday, January 24, 2012

River runoff and stranded seeds

During a bird survey on Salmon Creek Beach today, I noticed a significant amount of woody debris washed up on the beach.  Recent rains must have caused a lot of material to flow down Salmon Creek and the Russian River (the Russian River is ~10 miles north of Bodega Head).  Longshore currents transported, and then waves deposited branches, leaves, and seeds high on the beach.  Examples of species represented — Douglas-firs, redwoods, oaks, willows, maples.   In addition, do you recognize the seed in the photos below?

If you guessed California Buckeye (Aesculus californica), you're right!  There were at least 12 or more buckeye seeds in the wrack line along ~2 km of the beach.  Note that this one had started to sprout (look for yellow-green shoot emerging at top left).

They're impressive seeds the diameter is listed as 2-5 cm in The Jepson Manual.  I think this particular seed was even larger.  With the pencil for scale (the metal portion below the eraser is 1.5 cm long), I'd estimate it was ~6.5 cm across.

Monday, January 23, 2012

The longest animal on Earth!

On 21 January 2012, students on a UC Davis invertebrate biology class field trip found a siphonophore floating in Bodega Harbor.

Siphonophores are cnidarians — they're related to hydroids, jellyfish, sea anemones, and corals.  But they're pelagic (normally found far offshore) and often live deep below the surface, so are unfamiliar to many people. 

Siphonophores are very complicated free-swimming colonial animals.  They consist of many different units, specialized for locomotion, feeding, defense, or reproduction.  They're carnivores, extending long tentacles equipped with powerful stinging cells to capture smaller animals (including small fish). [Look for the yellow-orange strings of tentacles in the photos.]  Note that these stinging cells are very potent.  If you see a siphonophore and want to take a closer look, it's best not to handle them directly.

The siphonophore pictured below may be Praya dubia.  Remarkably, this species is one of the longest animals on Earth.  Although this is a small section of one colony (the larger transparent flask-shaped structures are ~1 cm long), some individuals stretch to 40 meters in length!  (The longest blue whale recorded was about 33 meters.)

Praya dubia lives in midwater habitats 700-1000 meters deep, so finding one at the surface close to shore is a real treat!


Sunday, January 22, 2012

Lichens

I was a little hesitant to post these photos, as I know very little about lichens.  However, I've always been drawn to them — they somehow feel ancient, and have attractive structures and colors.  And perhaps someday someone out there will be able to help identify the species in these images.

Lichens consist of several organisms — a fungus and a photosynthetic partner (alga and/or cynobacteria).  They become more noticeable after rains, expanding and brightening with newly available moisture.  On Bodega Head, lichens can be found on a variety of surfaces including rocks, trees, bones, driftwood, and even rabbit droppings!

Here are a few photos from 21 January.  

Note the red parts on the species above are reproductive structures where spores are produced.



The photo below is from February 2009, but I couldn't help including it, as it's proof of their occurrence on rabbit droppings (for you nonbelievers!).

Saturday, January 21, 2012

Salamander weather

Intense rainfall during the past couple of days made me think about salamanders.  They aren't common on Bodega Head — there isn't much surface water around — but can be found occasionally in moist habitats.  Today I encountered one of the most fascinating species the Arboreal Salamander (Aneides lugubris).  

Arboreal Salamanders live in oak woodlands, but also occur in coastal marshes and dunes.  They have expanded toes and a prehensile tail for climbing and have been found up to 60 feet high in trees!  Adults are brown with yellow spots, but juveniles are darker with blue spots and metallic tones.  These two juveniles were approximately 4 cm long.


Check out the bright blue spots!

Thursday, January 19, 2012

Storm clouds

Finally, some rain!  It's been a very dry winter so far (I read in the S.F. Chronicle that December 2011 was the driest December of the past 22 years), but today brought the beginning of a storm.  

I didn't take any photos today, but here are a few from 2010.  Two of these are from a similar time period 20 and 22 January.  The third image is from 30 March.  I've always loved the intensity of storm clouds, and ominous sheets of rain on the horizon.


Wednesday, January 18, 2012

Feather puzzle

While exploring the dunes on 16 January 2012, I encountered several piles of bird feathers.  Most of them looked like this.  Can you guess which species they belong to?  (Spoiler alert: My suspicion is below the image.)



If you're still puzzling over them, here are two more scans, showing the wing feathers aligned -- one from above (upper surface) and the other from below (second image).



I suspect these feathers belong to a Varied Thrush.  Visualize the wing patterns -- strong tawny-colored stripes and wing bars above and a white band below.  If you're not familiar with Varied Thrushes, you can see images and read more about them (and listen to them!) here at the Cornell Lab of Ornithology website.

(Note that the long feathers with white tips are tail feathers.)

It's a little puzzling, because I've never seen a Varied Thrush in the Bodega Dunes.  They're more typically associated with forests.  It's likely that a predator caught and then ate them in the dunes leaving the feathers behind -- perhaps it was a raptor, such as a falcon or an owl?  But the question remains, where did the predator capture them?  Where are the closest thrushes?  Or could they have been caught while flying over during migration?

I would have had a more difficult time identifying these feathers if Peter Connors hadn't shown me a few of the same type of feathers the day before I encountered these!  He discovered them at Salt Point.

Tuesday, January 17, 2012

Crossroads

Open sand in the dunes is wonderful for revealing animal tracks.

Here two animals crossed paths — a small mammal with sets of four small circular depressions (probably a mouse) and a bird (probably California Quail).  Did the mouse pass by at night, and the quail during the day?




And here's a typical rabbit track the two larger hind feet are in front placed side-by-side (upper left), and the two smaller front feet are in back, one in front of the other (lower right).

Monday, January 16, 2012

What does wind look like?

We've had two days of very strong northwest winds — 20–30 knots with higher gusts.  Bodega Head is one of the windiest places on the West Coast.  It's a challenge to consider how to represent wind in a photograph.  (Of course, there's nothing like feeling the brunt of it in your face, or almost being knocked over by it!)  Here are a few photos showing the interplay of wind, waves, and light.


And just when I thought the wind was too strong for a bird to fly into, a Peregrine Falcon comes into view, stroking powerfully upwind.