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Tuesday, July 31, 2012

Red-throated diver

 
Smallest of the loons, the Red-throated Loon (Gavia stellata)
  
On 30 July 2012, this individual was sitting on the beach, but then pushed along the sand into the water and swam away.

Red-throated Loons tend to hold their bills pointed slightly upward.  In breeding plumage, look for the uniform gray head (and sides of the neck).  The Birds of North America account states that this color is variable and may be described as "bluish, ash, pearl, glossy dark, dove."

There is a striking pattern of black and white stripes running from the crown down the hindneck (see below).  Note that the back lacks the strong white patches common to other species of loons in breeding plumage.


The foreneck has a beautiful rust-red patch (see next photo).  [In Europe, Red-throated Loons are sometimes called Red-throated Divers.]


Red-throated Loons are common winter residents in the waters surrounding Bodega Head (including Bodega Harbor).  Their spring migration occurs primarily in April-May and fall migration generally begins in September. (They breed from Alaska to southern British Columbia.)  Although less common from June-August, "almost annually a few birds summer over at Bodega Harbor and other coastal sites" (Birds of Sonoma County by Bolander and Parmeter).

P.S.  Do you know how many species of loons there are in the world?  And how many of those have been spotted at or near Bodega Head? (SPOILER ALERT: Answer is in next sentence.)

P.P.S.  All five species of loons in the world have been documented at Bodega Head (Arctic, Common, Pacific, Red-throated, Yellow-billed).


ADDENDUM (8 August 2012):  In response to the comment/question asking about whether I have a picture of the loon making its way down the beach.  I didn't get a picture at that time, but I have one of the loon just as it entered the surf zone (see below).

 

Monday, July 30, 2012

Washed ashore

Beachcombers know that it's not uncommon to find small, mysterious bits of gelatinous material washed ashore.  Unfortunately, it's often difficult to identify the animal that the material came from.  

Yesterday, while picking up trash on a local beach, I encountered a large gelatinous animal that seemed almost whole:

 
This is a pelagic tunicate known as a salp (nearshore benthic tunicates are commonly known as sea squirts).  Because they are most often found farther offshore, they're unfamiliar to most people (including me).

With some help from Steve Haddock and Larry Madin, this species has been confirmed as Thetys vagina, one of the largest salps on the West Coast.  In the photo above, there are several features visible: 

- a mouth-like opening on the left end (oral siphon)
- vertical lines across the mid-sections (muscle bands)
- a bulbous feature on the upper right with purplish color inside (internal organs)
- a large atrial siphon at the lower right end

The photo below, with the salp flipped over, shows a better view of the atrial siphon (now on the lower left) and muscle bands.


I'm a little uncomfortable describing the life history of Thetys, as it's difficult to find information about them.  But it's important to know that they alternate between a solitary phase (asexually reproducing) and an aggregate phase (sexually reproducing).  The animal in these photos is an individual from the aggregate phase — it's one of many that form a long chain.  There's a picture of a chain here and a nice image of a solitary form here.

In the Light & Smith Manual (2007), Larry Madin writes:

"Although ascidian tunicates are commonly found on rocks, pilings, piers, and other hard substrates largely in the subtidal zone, their planktonic relatives, the pelagic salps, doliolids, pyrosomes, and appendicularians, are rarely seen in the intertidal.  These pelagic tunicates are usually offshore species, distributed widely in the slope water and open ocean.  They may occasionally come into shallow water or even be washed up on beaches when offshore populations are pushed in by currents or wind."

After a relatively calm period, strong northwest winds started on 28 July 2012 and perhaps played a role in driving these salps on shore (I encountered three individuals on 29 July and one individual on 30 July).

Sunday, July 29, 2012

Vermiculations and a rippled trill


Yesterday was a "three tattler" day!  Previously I'd only seen one or two individuals at once, but I observed three Wandering Tattlers (Tringa incana) on 28 July 2012.  Most tattler sightings are of one or two individuals.  In The Birds of Sonoma County, there are only two other definite records of three birds.  [As far as I can tell, there haven't been sightings of more than three individuals at one time in Sonoma County.]

All of these photos are of one individual.  Note the dark barring on the underparts, sometimes described as vermiculations (i.e., marked by irregular or wavy lines).  Also visible are the large yellow feet (good for gripping rocks?).


Tattlers can have a very different profile depending on whether their neck is outstretched or pulled in.  In the photo below, look for the primary projection how far the tips of the primaries (outermost wing feathers) extend past the tail.


Here's a good view of the stout, straight bill and the relatively short yellowish legs. 


If you'd like to listen to a Wandering Tattler call, here's a recording I made on Bodega Head.  Among the waves, listen for the rippled trill call in this case, four notes sometimes written as ki-ree-ree-ree.  [The same call is heard three times.]

wandering tattler by nhbh

P.S.  There's more about tattlers in this post from 20 April 2012

Saturday, July 28, 2012

Spotted on the sea coast


Not a great shot, but the only one I got of a Spotted Sandpiper (Actitis macularia) on the outer coast of Bodega Head on 28 July 2012.  

They're listed as a rare migrant on Bodega Head, and an uncommon resident of Sonoma County.  Although there are nesting records along the Russian River, this sandpiper is not often seen on Bodega Head itself (I've only seen a few).  Their winter range extends along the Pacific Coast from southern British Columbia to central Argentina.

Note the bold black spots on the breast and belly, the black bars on the upper feathers, and the orange bill with black tip all indicators that this individual is still in breeding plumage.

According to The Dictionary of American Bird Names (Choate, revised by Paynter, 1985), the genus Actitis comes from the Greek aktites = "a dweller on the sea coast."

Friday, July 27, 2012

Spot on


During the summer, a few days of south winds and warm, still conditions can bring sightings of migrant dragonflies to Bodega Head.  Today I encountered a small swarm of Spot-winged Gliders (Pantala hymenaea) feeding over lupines.  

Luckily, a few of them landed briefly in between feeding bouts.  In the photo above and below, look for the very broad hind wings with a narrow dark spot at the base.  This mark gives this species its common name.  It's relatively easy to see in these photos, but can be difficult to see in flight.


Also note the handsome markings on the abdomen, another characteristic that's much easier to see when the dragonflies are perched.

 
This is a relatively large-eyed, short-bodied, broad-winged species.  This genus has been documented traveling great distances, even hundreds of miles out to sea!  The broad wings aid in long-distance flights.  Species in the genus Pantala have also been called "globetrotters."
 

Thursday, July 26, 2012

Flukes


The descending flukes (tail) of a small Gray Whale (Eschrichtius robustus) off Bodega Head on 17 July 2012.  Note the deep central notch.

Wednesday, July 25, 2012

Mint green and fuzzy


A beautiful bee photographed on Seaside Daisy (Erigeron glaucus) on Bodega Head, 23 July 2012.  I was taken by the mint green eyes and the noticeable white hairs, giving the bee an extremely pale and fuzzy appearance!

I'll check in with a few bee experts to see if we can identify this species.  If you're familiar with local bees and have some thoughts about this individual, I'd be grateful for any information.  Could it be a type of long-horned bee?  [Addendum 26 July 2012: Yes!  Robbin Thorp confirmed that this is a male long-horned bee, Melissodes pallidisignata.]

Here are two more views:




Tuesday, July 24, 2012

The subtidal pulmonate


Okay, here's a species that I don't know much about, but am too intrigued by not to share.

This is Williamia peltoides, a marine pulmonate.  Most pulmonates are air-breathers (e.g., land snails and slugs), but Williamia lives in the subtidal zone.  I've occasionally found Williamia shells washed up on the beach, but this year I've encountered a few live individuals.

They look very similar to limpets, and are in a family that is sometimes referred to as "false limpets."  The photo above shows their limpet-like shape.  Note the pretty purple-red coloration with radiating white stripes.

They crawl on very large foot (see next photo).


In the photo above, you can also see a few interesting features.  Note that they don't really have obvious tentacles (as do true limpets).  Instead, they have rounded tentacular lobes.  I believe that little black spot surrounded by white on the right side of the head is an eye.

Behind the head, on the right side, you'll notice two other mysterious structures (see close-up below).


The leftmost structure with several layers or lamellae (that makes it look corrugated) is a gill-like organ.  It's not a true gill, and this feature separates them from true limpets (and is even unusual for pulmonates).  The rightmost structure is rounded and flap-like.  From what I can determine, this is an anal lobe and contains the anal opening.  The undulating purple feature (with white spots) is the side of the foot.

A couple of other interesting notes about Williamia: They have a thin periostracum (a chitinous layer covering the shell) that often extends beyond the edge of the shell (unfortunately, it's not visible in these photos).  And they release a white mucous when disturbed to deter predators.  [Trimusculus, another marine pulmonate on Bodega Head, also releases toxic mucous that can paralyze sea star tubefeet!]

 
Williamia peltoides on Bodega Head, 7 July 2012.

Monday, July 23, 2012

Lobo marino

California Sea Lion (Zalophus californianus)

Swimming near shore off Bodega Head on 23 July 2012.  Note the upturned snout and small ear flaps (pinnae) behind the eyes.

California Sea Lions (or lobo marino de California in Spanish) haul out on Bodega Rock.  Their loud barking calls can be heard throughout the Bodega Head and Bodega Harbor area.

Here are two more views of California Sea Lions, both offshore during a boat trip to Cordell Bank and Bodega Canyon in October 2011.



This sea lion (on the right) was "porpoising" with a small group of Pacific White-sided Dolphins.  Note the uniform brown appearance and the streamlined profile.

Sunday, July 22, 2012

Monardella

Coyote-mint (Monardella villosa ssp. franciscana)


A highly aromatic native perennial growing in coastal prairie on Bodega Head.  Below is a close-up of the flowers.  Look for the 2-lobed upper lip and the 3-lobed lower lip.


The genus, Monardella, means "little Monarda."  Monarda is the genus for other plants in the mint family that you may be familiar with, e.g., Bee Balm and Wild Bergamot.  Monarda was named after Nicol├ís Monardes, a 16th century Spanish physician and botanist.

Saturday, July 21, 2012

An exceptional spine


If you haven't yet seen the larval stage of a porcelain crab, you've been missing out!  


On 18 July, I posted a picture of an adult porcelain crab.  Tonight's post features the larval swimming stage called a zoea.  The larva looks nothing like the adult.  

Porcelain crab zoea spend ~40 days in the plankton, molting several times before becoming a megalopa — the last larval stage before transforming into a benthic (bottom-dwelling) juvenile crab.

Note (not that you won't!) the exceptionally long inflexible spines.  The forward-projecting spine is called a rostral spine.  It's thought that this spine deters potential fish predators.  Here's a close-up:

 For scale, this zoea was ~2 cm long — remarkably long for a larval crab.
    
This porcelain crab zoea was collected in a plankton tow near Bodega Rock (off the southern tip of Bodega Head) on 16 July 2012.

If you were a fish, would you try to eat this larva for dinner?
 

Thursday, July 19, 2012

Short-billed (and short-legged)

Short-billed Dowitchers (Limnodromus griseus) swimming towards shore as the tide flooded the tidal flats in Bodega Harbor on 14 July 2012.  (They're surrounded by the standing, longer-legged Marbled Godwits and Willets.)

Here's another view of a resting Short-billed Dowitcher (taken in the spring).  The dowitcher is the bird in center, with short greenish legs.  There is a Red Knot just in front and to the left of the dowitcher.  They look similar at first, but note the difference in feather patterns.


An even closer view with a dowitcher (right) and knot (left) side by side.  Compare the large red oblong spots on the knot's feathers with the thinner, jagged bars on the dowitcher's feathers. 


Their bills are different, too.  Look for the longer bill of the dowitcher, with a relatively uniform width throughout...versus the shorter bill of the knot, with a thicker base tapering to the tip. 

(Dowitcher is lower left, knot is upper right.)


Dowitchers are known for their very regular up-and-down feeding motion (deep probing), sometimes likened to a "sewing machine."


The above picture was taken in April while dowitchers were migrating north.  Remember that the first photo was taken in mid-July.  Dowitchers have already finished their nesting season (in the muskegs of Canada!) and are now migrating south — a very quick turnaround.  They will spend their non-breeding season along the Pacific Coast between northern California and Peru.


P.S.  There's a fun connection between dowitchers and Bodega Head.  Frank Pitelka, a UC Berkeley professor who was instrumental in establishing the Bodega Marine Laboratory, studied dowitchers in Alaska.  He confirmed that there were actually two species — Short-billed Dowitcher (Limnodromus griseus) and Long-billed Dowitcher (Limnodromus scolopaceus) — and also described several races of Short-billed Dowitcher that have different breeding areas and migration routes (e.g., Pacific, Prairie, Atlantic).

Wednesday, July 18, 2012

Blue on brown


A very pretty porcelain crab — wouldn't you like to have blue spots like that?  We think this is a Chocolate Porcelain Crab (Petrolisthes manimaculis; note that 'manimaculis' means 'spotted hand').  But I neglected to look for a confirming characteristic in the field an orange spot inside the base of the movable finger of the claw.  (If you have an opinion about the i.d., feel free to chime in.)

This individual was photographed on Bodega Head on 4 July 2012.  The entire crab was ~4 cm across.

Chocolate Porcelain Crabs are reported to reach their northern range limit near Bodega Bay, but we've found them as far north as Fort Ross. 

This species is potentially the least common of the four species of porcelain crabs on Bodega Head.  We'll feature the others in future posts!
 

Monday, July 16, 2012

Striped socks


Acmon Blue (Plebejus acmon) photographed at Campbell Cove on 31 May 2012.  Check out the striped antennae and striped "socks"!  During spring, both males and females are blue above:


Local host plants (species on which the caterpillar feeds) for Acmon Blues include legumes (e.g., Lotus spp.) and Seaside Wild Buckwheat (Eriogonum latifolium).

Here's an individual nectaring on buckwheat in the dunes in August 2010.  In the second photo, look for the long tubular proboscis probing the flowers (it's between the antennae).



Acmon Blues fly almost year-round in this area.  (Other species have a more restricted flight season.)  Watch for these small blue butterflies (forewing is ~1 cm long) fluttering at ground level where their host plants are found.

Sunday, July 15, 2012

Giant Bur-Reed


These are the flowers of Giant Bur-Reed (Sparganium eurycarpum), a native perennial found in freshwater wetlands on Bodega Head.  It's hard to tell from these pictures, but this is a large plant with cattail-like leaves growing up to 2.5 meters tall (the leaves are keeled at the base).

The large flowers below are females, with long white stigmas.  (In the photo below, there are male flowers above and to the right of the females, but they're not open yet.)



The male flowers are located above the females.  They open at different times, with the lower flowers maturing before the upper flowers.  In the next photo, the lowest flowers are wide open, the middle flowers are starting to open, and the highest  flowers aren't open yet.


For some reason, this plant always reminds me of Dr. Suess:

Male flowers
Follow female flowers
And male flowers create zigzag towers

I could look at these flowers
for hours and hours
even while it showers!

Saturday, July 14, 2012

Sand-encrusted capsules

This is a follow-up to the Tinted Wentletrap post on 26 June 2012.

I had wondered if there were egg capsules next to one of the snails.  I went back to take a closer look, and here's what I found.


Sure enough, they were egg capsules!  Tinted Wentletraps lay small egg capsules (~1 mm across) that are encrusted with sand and strung at intervals along a thin, elastic strand (see next photo).


One of the capsules was cracked open and you could see tiny white embryos inside:



Amy Breyer described these capsules in her Master's thesis at Sonoma State University in 1981 (Observations on the reproduction, feeding, and ecology of the wentletrap, Epitonium tinctum).  She found between 17-60 eggs in each case, with larger females producing larger capsules and more eggs per case. 

Impressively, she was able to watch the females producing egg capsules first releasing a mucous-coated capsule, then attaching it to the thread, and finally molding sand grains (collected in a pocket within the snail's foot) around the capsule before it hardened.

It takes about a week for the embryos to hatch and emerge as larvae from the capsules.  This stage (called a veliger) then swims in the plankton before eventually undergoing metamorphosis into a juvenile snail.

Here's one more view of these unique capsules:


You may be wondering, why does the snail bother to coat the capsules with sand?  Although I don't think it has been studied yet, Amy suggested several hypotheses: camouflage, defense against predators, or protection from physical factors (wave action, desiccation, temperature changes).  Which do you think it is?  Or do you have other ideas?


Friday, July 13, 2012

Elephants in the mussel bed?


Recently I encountered these tiny white snails clustered on a California Mussel (Mytilus californianus).  They're called odostomes and appear to be Evalea tenuisculpta.  Each one is less than 5 mm long. 
 
Initially, I was trying to learn more about the egg capsules of these snails (see below).  

I saw one snail approaching the egg mass above, and was surprised to see it turn and start to evert a very long proboscis (an elongated tubular appendage).  It extended the proboscis between the two valves (shells) of the gaping mussel!

I could see fluid or particles moving inside the proboscis towards the snail, and thought perhaps it was stealing food from the mussel.

In turning the mussel slightly for a better view, I was puzzled to see the proboscis tip flat against the mantle (outer tissue) of the mussel.


Here's an even closer perspective. The orange is the mussel's tissue.


I was then further shocked to see something inside the proboscis stabbing the mussel, followed by distinct pumping action drawing fluids up into the proboscis.

After doing some research, I found this somewhat frightening description of a related species feeding on a worm:

"Then suddenly the sucker grips the epithelium of the filament, and the stylet may be seen to drive outwards so that it is clearly being used to perforate the body of the worm.  Vigorous pumping movements of the buccal apparatus may then be seen and it is obvious that fluid, blood, and perhaps, cells loosened from the worm are being sucked into the gut of the pyramidellid."  (Fretter & Graham 1949)

These small snails are ectoparasites (parasites living on the outside of another animal) that practice suctorial feeding!

Here's a nice illustration of yet another species feeding on blue mussels:

(From Advances in Marine Biology 1967, redrawn after Fretter & Graham 1962)


Another unusual feature of these snails is the shape of their tentacles.  They are broad and flap-like, with a concave surface, and can be adjusted to face in different directions.  In combination with the very long trunk-like proboscis, they give this diminutive snail a very elephant-like appearance.



Who knew there were tiny elephants in our local mussel beds?