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Saturday, March 31, 2012

Toothy

You're not going to believe this.  I found what I thought was a dead shark on the beach.  I turned it over to get a closer look at the teeth, and it tried to bite me!


No, just kidding — Happy April Fools' Day!


But I did encounter the head of a shark washed up on the beach, most likely a Leopard Shark (Triakis semifasciata).  Here are photos from above and below (taken on 30 March 2012).  Note the black bands and spots above, and the large nares (nasal openings) in front of the mouth.



Leopard Sharks are locally common in Bodega Harbor and Tomales Bay.  They feed on benthic invertebrates, e.g., crabs, shrimp, clams, and innkeeper worms.  As adults, they measure about 4-5 feet long.  They give birth to live young (~8 inches long) during the spring/summer season (primarily in April and May), often in eelgrass beds.

I've read that Leopard Sharks are sometimes eaten by Great White Sharks (Carcharodon carcharias).  Great Whites are known to spend time in the Bodega Bay region.  Here's a tooth from a Great White that I found on a local beach in 2005.  It's worn like sea glass, so the serrations along the edges aren't as visible in this scan (although you can still feel them on the tooth).


The genus, Carcharodon, means sharp or jagged tooth.  White sharks are impressive apex predators.  They can reach 20 feet in length and may weigh over 5,000 lbs.  Not kidding this time! 

Friday, March 30, 2012

The first damsel

On 17 March 2012, I came across this damselfly near the Hole-in-the-Head/Campbell Cove.  I didn't have the right lens with me at the time, so I hope to post better photos in the future, but here are a couple of images to serve as an introduction to this attractive group of insects.

 Pacific Forktail (Ischnura cervula)

Field marks to note: very small blue postocular spots (behind the eyes), four blue dots (two on each side) on top of the thorax (between the head and the abdomen), solid blue on the sides of the thorax, mostly black abdomen with blue on segments 8 and 9 and black on the last (or 10th) abdominal segment. 

View from the side:


Pacific Forktails are common in wetlands with dense aquatic vegetation.  They are one of the first damselflies to emerge in the spring.  Freshwater wetlands are uncommon on Bodega Head, which can make finding odonates (dragonflies and damselflies) challenging.  But watch for Pacific Forktails flying among rushes in local freshwater marshes and even in wet roadside ditches (e.g., along Westshore Road).

Thursday, March 29, 2012

The clam and the tunicate

Here's a photo from late February.  Recent stormy sea conditions made me wonder if more of these might have washed up on local beaches this week.

Two Sea Bottle Clams (Mytilimeria nuttalli) are embedded in a purple tunicate (possibly Cystodytes lobatus?).  Normally the clams are completely covered by the tunicate, but here a portion of the tunicate has been torn away, revealing the clams below.

Unlike most clams that live in sandy or rocky substrates, Sea Bottle Clams are usually found living within tunicates (in the low rocky intertidal zone or shallow subtidal areas).  While most of the clam is hidden below the surface, they can extend their siphons into the water through a small narrow slit in the outer covering of the tunicate to feed.

These clams may reach 4 cm in length, but individuals ~2 cm long are more common.  Their shells are quite thin and fragile given protection by the tunicate, this clam doesn't need to produce a thicker shell.

The interior of Sea Bottle Clam shells is beautiful and often described as lustrous or pearly (see below).

Although not much is known about their life history, it's thought that juvenile Sea Bottle Clams attach to a tunicate with a byssal thread (like those used by mussels), and then the tunicate grows up around the young clam. 


ADDENDUM (30 March 2012)

Sure enough, during a quick walk on the beach this morning I encountered a few more Sea Bottle Clams.  Here are two shots from 30 March.  

The first shows the slit through which the siphons are extended (as well as a smaller clam to the right of the slit).  The second is another attempt to capture the polished interior (it's better to see this in the field!); it also shows how thin and fragile the shell it.

Wednesday, March 28, 2012

On the rocks

Coast Rockcress (Arabis blepharophylla)

An early spring perennial growing around rock outcrops, along coastal bluffs, and on grassy slopes.  Flowering from February through May, with peak in March and April.

Look for bright pink petals (pale in some individuals, darker in others), oval basal leaves and cauline leaves (growing along the stem) that are often hairy.

Seeds are contained in long, narrow pods ~2-4 cm long (see below).


On 23 March 2012, I noticed a few flowers being eaten by woolly bear caterpillars (Platyprepia virginialis, which will become Ranchman's Tiger Moths).  


[For East Coast readers that I know are probably wondering, although also called a woolly bear, this is different than the familiar caterpillar with the same common name (or sometimes called a banded woolly bear) in the eastern United States.  That species is Pyrrharctia isabella and it becomes an Isabella Tiger Moth.]


We're lucky to be able to enjoy this lovely California endemic on Bodega Head.


Tuesday, March 27, 2012

Doran Beach birds

A few bird photos from Doran Beach on 25 March 2012.

Least Sandpipers (Calidris minutilla) roosting among new shoots of Sea Rocket (Cakile maritima).


Semipalmated Plovers (Charadrius semipalmatus) and Least Sandpiper (Calidris minutilla) resting among four beach plants — Beach Bur-sage (Ambrosia chamissonis), Sea Rocket (Cakile maritima), European Beachgrass (Ammophila arenaria), and Beach Saltbush (Atriplex leucophylla).


Snowy Plover (Charadrius alexandrinus)


Forster's Terns (Sterna forsteri)


Surf Scoters (Melanitta perspicillata) with Point Reyes in the background visible from left to right are the mouth of Tomales Bay, Tomales Point, and Bird Rock.  Although it's about 11 km (6.8 miles) across Bodega Bay (from Bodega Head to Tomales Point), it often feels closer!

Monday, March 26, 2012

Silver and gold

Wet weather ahead (and this past weekend) had us thinking about salamanders again.  This time we encountered a different species (past posts have covered Arboreal Salamanders and Ensatinas).  

The species below is the more common of the three.  It prefers moist forests, but has been seen on Bodega Head.  (These photographs were taken in Sebastopol.)  They are almost California endemics, most common in north central California with the range barely extending into southwest Oregon. 

California Slender Salamanders (Batrachoseps attenuatus) are sometimes mistaken for worms or small snakes because their bodies and tails are very elongate and their limbs are so short (it can be difficult to see the legs at first but see photo below).  Coloration is variable, with grays, browns, reds, and oranges predominant.


Slender Salamanders are plethodontids, or lungless salamanders.  Their entire existence is terrestrial, with eggs being laid in underground tunnels or beneath objects resting on the forest floor.  Eggs are deposited when the rains begin in the fall and tiny salamanders hatch out approximately 80 days later.

This salamander displays a variety of anti-predator behaviors: coiling (see below), thrashing or springing away, crypsis, sticky skin secretions, and tail autotomy [this info from amphibiaweb.org].


Check out these beautiful silvery "eyebrows" and the hint of gold in the eyes!


Sunday, March 25, 2012

Ladies and ladies

Bodega Head is generally a difficult place for butterflies — it's often cold and windy.  But when the sun is out and the wind is calm, if you search in sheltered locations you might encounter them.

On 25 March 2012, I noticed this butterfly basking on the ground at Doran Beach.


It's a West Coast Lady (Vanessa annabella), one of three ladies that may be seen in this area.  A couple of important field marks (highlighted below): all four of the hindwing spots have blue centers and the large spot on the leading edge of the forewing is orange.


In the other two species, the hindwing spots either don't have blue centers (Painted Lady, Vanessa cardui) or only two of them do (American Lady, Vanessa virginiensis).

In Painted Ladies and American Ladies, the large forewing spot on the leading edge of the forewing is usually white, or sometimes pale orange (paler than the rest of the orange on the forewing) — see next two photos.


This photo above was taken on 4 March 2012.  Note the colors of the forewing spot and the hindwing spots (red circles below), and that there is generally less black in the inner forewing (pink circle below).  

My best guess for this species is American Lady.  Most American Ladies also have a small white spot inside the orange on the forewing (see white arrow below).  It's missing in this individual, but that's a known variation, and everything else seems to fit for American Lady.  (Let me know if you have a different opinion!)


If you're interested, there's a checklist of butterflies seen at Point Reyes available on the National Park Service web site.

Saturday, March 24, 2012

Going up and coming down

While working at home in Sebastopol today, one of my favorite birds appeared outside the window.  Although steady rain was falling, I ran outside to see if I could capture an image.  Can you find the bird on the redwood trunk?


This is a Brown Creeper (Certhia americana).  The quote at the beginning of the Birds of North America account is a perfect description:

“The brown creeper, as he hitches along the bole of a tree, looks like a fragment of detached bark that is defying the law of gravitation by moving upward over the trunk, and as he flies off to another tree he resembles a little dry leaf blown about by the wind.” Tyler (1948)

Brown Creepers are small (12–13 cm long) tree-climbing passerines.  They're the only representative of the treecreeper family in North America.  Their coloration is cryptic, brown above with white/buffy spots and streaks and generally white below.  

Note the long, thin decurved bill (for gleaning insects and spiders from furrows in the bark), distinct supercilium (eyebrow stripe), long tail (used as a prop against the trunk), and long curved claws (for grasping pieces of bark).


Creepers forage in a predictable pattern, starting at the base of a tree, climbing up to near the top, then dropping down to the base of a different (or the same) tree to start again.
 

Their high-pitched calls and songs are distinctive once you are familiar with them — a sibilant tsee note or a longer song tsee-tuti-sedu-wee .  You can listen to them here.

Amazingly, creepers build hammock-like nests between the trunk and a loose piece of bark.

Almost everything about Brown Creepers is an adaptation for living closely with large, old trees.

Friday, March 23, 2012

Cloud shadows

23 March 2012
Wind from the east/southeast, 10-15 mph (cold front approaching)
5 ft. swell (calm before the storm)


Note the brownish band close to shore — an accumulation of phytoplankton that's been visible since Monday, 19 March 2012.

Thursday, March 22, 2012

Poppies!

Three species of poppies are found on Bodega Head.  All three have started to flower.

California Poppy (Eschscholzia californica)

On the coast, this species is a perennial, and its flowers are bicolored.  The four petals generally have orange bases and yellow tips.  You'll find them in both grassland and dune habitats, as well as along roadsides.  It's the most common of the poppies on Bodega Head (and is the California state flower).  Interestingly, it was first collected and described during Russian expeditions to this area in the early 1800s (Eschscholtz was a surgeon/botanist on one of the voyages.)


Cream Cups (Platystemon californicus)

An annual, primarily found in coastal grasslands, especially along the outer bluffs.  Six petals, with variable amounts of yellow and white (or cream).  All of the petals on one flower are generally similar in color (contrast with next species).


Evening Poppy (Hesperomecon linearis)

Formerly known as Meconella linearis.  The common name has not been standardized.  Sometimes referred to as Popcorn Poppy or Carnival Poppy.  Hespero = evening or west, and mecon = poppy, hence the name above.  Of the six petals, the inner three are mostly white and the outer three are mostly yellow.  This is the rarest of the poppies on Bodega Head and is only found at a few sites in older, remnant stabilized dunes.  It's also rare in Sonoma County, with perhaps just one or two other known locations.

Wednesday, March 21, 2012

Beach hoppers, Part 2

After last night's post, Molly inquired about a beach hopper she observed recently on a beach in northern Sonoma County — one with red antennae rather than blue.  It's possible the species she encountered is similar to the one pictured below (this photo was taken on Bodega Head on 16 June 2011).

This is Megalorchestia corniculata (formerly Orchestoidea), sometimes called the short-horned beach hopper.  The "horns" are actually antennae, and "short" is relative to another species, Megalorchestia californiana, sometimes called the long-horned beach hopper.

The illustrations below show the differences in the antennae.

Illustrations from Bowers, D.E.  1963.  Field identification of five species of Californian beach hoppers (Crustacea: Amphipoda).  Pacific Science 17: 315-320. [Part of this research was conducted at Dillon Beach.]

In the top figure, showing Megalorchestia californiana, the second antenna is very long, especially the last segment, or flagellum (it's longer than the combined length of the peduncle segments).  In the second figure, note the much shorter flagellum of Megalorchestia corniculata.

Another difference between the two species is the color of the second antennae.  In M. californiana it's usually rose-red; in M. corniculata it's usually salmon-pink.

Here's a close-up of the second antenna of the animal pictured above:


The beautiful purple eye is also quite striking.  Amphipods have compound eyes made up of hundreds of units called ommatidia (photoreceptor cells). For comparison, large dragonfly eyes may have up to 30,000 ommatidia!  (More about them later.)

Just for fun, here's another species of amphipod that lives in high tidepools.  Check out the fancy and variable color patterns!

Tuesday, March 20, 2012

Let's go to the hop


Three views of a beach hopper.  Unfortunately, I don't know what species this is, but I couldn't resist posting the photos — their blue antennae and legs are so intriguing!  

If you've spent any time on the upper beach, especially at dusk or at night, you've probably encountered beach hoppers.  Formally, they're talitrid amphipods, shrimp-like crustaceans that are laterally compressed.

Note the large compound eyes, long antennae, and well-developed legs.  When walking, the posterior legs are held out to the side for stability (see third photo).  Beach hoppers are capable of very impressive jumps.  The jump is achieved by curling under the end of the abdomen and then straightening it suddenly, which launches the animal into the air.  They'll often start jumping randomly to avoid predators (and may even feign death at the end of a series of jumps).

When not out feeding, beach hoppers burrow below the surface of the sand or find shelter under seaweed and other materials in the wrack line.  It's worth taking a closer look at them, and marveling at their saltatory abilities!

Monday, March 19, 2012

The watchful burrower

This is the smallest of the six species of owls that have been documented on Bodega Head.  I've been casually trying to get pictures of them for a while, but most often end up with just a blur.  These are still a little blurry, but at least you can tell that it's an owl and you can see some of the identifying features.  [Photos from the Bodega Dunes on 19 March 2012.]

Field marks to look for: small size (19-25 cm long), overall brown coloration with white spots, rounded head with broad white eyebrows and white chin, yellow iris, relatively long wings and long legs, short tail.

Burrowing Owls (Athene cunicularia) are listed as a Species of Special Concern in California.  They are rare winter residents (and migrants) on Bodega Head, occurring in both grassland and dune habitats.  Unusual for owls, this species is a ground-dweller and is active both day and night, although they tend to be crepuscular, with most hunting around dawn and dusk.  Preferred prey includes insects (e.g., grasshoppers, crickets, beetles) and small mammals.

Athene cunicularia = named after the Greek goddess Athena (known for wisdom and watchfulness) and for their underground habits (cunicularia = "a miner or burrower").


Burrowing Owls depend on open or sparsely vegetated habitats.  On Bodega Head they often use badger burrows for roosting (and sometimes dense clumps of vegetation or shrubs).  They haven't nested in Sonoma County since the 1980s.  Soon they will be departing the coast to breed in inland valleys.

P.S.  Happy Spring!  Vernal equinox at 10:14 p.m. on 19 March 2012.

Sunday, March 18, 2012

Gloriosa

Last night (17 March 2012), an amazing moth flew through an open door and into our kitchen.  In general, moths are underappreciated.  But when viewed up close, their beautiful colors and patterns are often stunning.  This one reminded me of a Persian rug.  

I think it's a species of Cerastis, perhaps Cerastis gloriosa.  (If someone out there is familiar with this species, it would be great to hear more about its identity and life history.)

Here's a view with wings closed.


And a closeup of the head and antennae.  Note that the antennae are not knobbed, i.e., they taper all the way to the tips.  (In contrast, most butterflies have knobbed antennae.)


The luxurious hairs behind the head look a bit like a lion's mane!
 
Here's a view showing the colors and patterns on the forewing.  This moth has probably just emerged from a pupa recently all of the scales look new and barely worn.  Individual scales are especially visible in the pink band just inside the fringe (those aren't pixels!).  

 
Remember that Lepidoptera (the group containing moths and butterflies) means "scale wing".  The scales are actually modified hairs that look somewhat like shingles on a roof when viewed under high magnification.

If this is Cerastis gloriosa, the account in Moths of Western North America (Powell and Opler, 2009) describes their flight period as late February to late April.

Saturday, March 17, 2012

Pacific Chorus Frogs

Rain for most of the past week created favorable conditions for amphibians.  The most common frog on Bodega Head is the Pacific Chorus Frog (or Pacific Treefrog), Pseudacris regilla.  You can encounter them just about anywhere, but for breeding they prefer shallow pools.

Here are a few photos from 17 March 2012.  


A male-female pair in amplexus (mating embrace).  The smaller male is holding the larger female from above.  Fertilization is external.  The female will attach eggs to a submerged object (see below), and the male will release sperm to fertilize them. 


View from above.


View from front.


Eggs are laid in small clusters attached to grass or twigs.  They are brown above and cream colored below and are embedded in a gelatinous matrix.


Note the rounded toe pads on the hind foot, a distinctive character of treefrogs.  For this species, the black line running from the snout past the eye and to the shoulder is a helpful field mark.


You can listen to Pacific Chorus Frog calls here.