Sea glass

More indoor time at a meeting today, but a dash out to the beach for a little fresh air allowed me to take a few close-ups of waves in Oxnard, CA.  I've always loved looking at patterns of light on water.  Sometimes the way light and water interact reminds me of glass. 

 

 

 

Beach break

I'm at a meeting in Oxnard, CA, and was indoors for most of the day.  But the meeting is at a hotel that's right on the water, so during a break I took a quick look at the beach and found a few birds nearby:

 

Long-billed Curlew (Numenius americanus)

There were a few curlews actively feeding in the swash zone.  They appeared to be catching small Mole Crabs (Emerita analoga).

 

 

Occasionally they would be joined by a flock of Marbled Godwits (Limosa fedoa), offering a nice comparison.

 

I also encountered several Snowy Plovers (Charadrius nivosus) resting higher on the beach:

 

 

Not such a bad meeting break!

Spiny!

Want to take a guess about the following mystery object?  (Warning: The answer is below the image.)

 

 

Did you guess part of a crab?  If so, you're right!  Here's the entire object.

 

This is the carapace (basically the "back") of a Spiny Mole Crab (Blepharipoda occidentalis).  I found it washed up at Doran Beach on 1 November 2013.  It was ~2 inches (5 cm) long.

Most people are familiar with a more common species of Mole Crab (Emerita analoga).  They're smaller, grayer, more rounded or domed, and lack the prominent spines.  Here are the two side-by-side for comparison (see next image).

 

When you find just the carapace alone and not the entire crab, it's often a molt, which means that the animal has shed its old exoskeleton (that's what you're looking at) but has grown a new exoskeleton and is still alive.

We moved to Sonoma County in December 2004 and were excited to find Spiny Mole Crab molts at Doran Beach and Salmon Creek Beach.  When you read about the distribution of Spiny Mole Crabs in books, you may see their northern range limit described as San Francisco, Stinson Beach, or Drakes Beach.  So it's quite possible that the observations at Doran Beach and Salmon Creek Beach are the northernmost records for this species in California.

In 2005, I found a live Spiny Mole Crab at Doran Beach.  They live in the very low intertidal zone and subtidal zone, so it's harder to find them than the more familiar Emerita analoga. 

For site documentation purposes, finding a live crab is better than finding a molt because a molt could wash in from farther away.  To say that Spiny Mole Crabs regularly occur at Salmon Creek Beach, it would be good either to find live Spiny Mole Crabs there, or to locate additional molts.  

This past week I had a strange experience in that I was remembering the Spiny Mole Crab molt that Eric and I found on Salmon Creek Beach in 2004.  I haven't seen one there since.  I haven't done a purposeful search for them, but I keep my eyes open as I'm walking the beach.  

Well, after I found the molt at Doran Beach on November 1st, I went for a quick walk on Salmon Creek Beach on November 2nd, and what do you know, there was a Spiny Mole Crab molt on Salmon Creek Beach (see picture below)!

 

We still don't know if there are Spiny Mole Crabs actually living at Salmon Creek Beach, so it'll be interesting to see if we can find a live crab there some day.  (Or let me know if you or anyone else you know has found one there or even farther north!)

Lift off

 

Peregrine Falcon (Falco peregrinus), Bodega Head, 4 November 2013

And the meadowlarks were eating...

I know, you've been wondering all day about the mystery food item featured in last night's post!  ;)

To review, here's the close-up that showed a Western Meadowlark holding a white squiggly thing with a brown object at one end:

 

I mentioned that I went out to the same area and dug around just like a meadowlark to try to find the same sort of object.  It didn't take very long!  I started finding them almost immediately.  I kept digging to see if there was more than one option, but this is the only match I found.

I brought it into the lab and took a few photos under the microscope.  The first shows the brown object with the white shoot off to the side, and the second is a closer view of a slightly larger brown object:

 

 

While digging, I also looked around to see if there was ever anything else at the other end of the shoot, and that was easy enough to find.  Below is an example.  It was a little too long for a microscope view, so I bent it around so you could see both ends:

 

And here's one of just the leaves of this plant (different individual), which might help with the identification:

 

This is Oxalis pes-caprae.  It has a variety of common names and is often known as Bermuda Buttercup.  But I like the name African Wood-sorrel, as it's originally from South Africa and although it has yellow flowers, it's not a buttercup!

Oxalis pes-caprae is known for having relatively large bulbs (but less than 2.5 cm long) from which underground shoots arise in the fall.  In fact, this species is invasive and difficult to eradicate because of the many bulbs that it produces.

I was a little surprised to find out that meadowlarks were eating Oxalis bulbs!  But I was also taken aback by the color and texture of the lower surface of the Oxalis leaves!  

In the field, many of the leaves were green below, but others were bright pink, as in the image above.  I couldn't help taking a closer look under the microscope.  I know it's a bit of a tangent, but you have to see this!

 

 

 

 

Isn't that amazing?  I looked at descriptions of Oxalis, and none of them mention this color.  Or that the leaves are glandular.  [I'm not sure what else this could be (other than glandular), but if you have different ideas, let me know.]  CORRIGENDUM 9 November 2013: I've done some additional research, and now believe these are bladder cells.  I'll explain a bit more later.

To wrap up, I'll go back to the main topic of this post — the Oxalis bulb being a food source for meadowlarks.  Out of curiosity I split open one bulb to see what the meadowlarks were after (see below).  When I first started watching the meadowlarks a few days ago, I had no idea it would lead me to the inside of an Oxalis bulb!

 

Watching my nemesis

Western Meadowlarks (Sturnella neglecta) are common winter residents in grasslands on Bodega Head.  Occasionally I've tried to photograph them, but they're quite wary, and I haven't had much luck.  Every time I almost get close enough for a picture, they take off and land just a little farther away and disappear among the vegetation.  When it comes to getting a good picture, they're a bit of a "nemesis bird" for me.  I just shake my head and sigh.

This weekend I was at work and I passed by a window to see a small group of meadowlarks very close by.  I wasn't sure how long they would stay in the area, or if it would be possible to photograph them through the window, but I decided to give it a try.  It was basically like being in a blind.

It was a fascinating experience.  I'd never watched meadowlarks feeding before!  The pictures aren't sharp because of the window and the fast movements of the meadowlarks, but they're still informative, so I'm excited to share them with you.

The meadowlarks would stride quickly across the ground.  I like this next picture because it emphasizes the strong and slightly curved bill.

 

They would use their bill to probe deeply into the vegetation or the ground.  The picture below also highlights the beautiful feather markings.

 

Sometimes they would open their mandibles and use their bill to flip over clumps of vegetation:

 

Digging with the bill was common.  In the image below, look for the soil being flung to the right side of the bird.  The meadowlarks were vigorous when digging, and now I understand how useful their strong bills are for this type of feeding behavior.

 

I saw them with food in their bills quite often, but it was difficult to identify the food items.  I feel fairly confident that this meadowlark found a large beetle larva (within blue circle in image below):

 

But the most common food item was mysterious at first.  While I was watching, all I could see were thin white squiggles in the meadowlarks' bills.  And then when I reviewed the pictures, I could see that sometimes there was something brown at the end of the white squiggle.  

Can you see the squiggles in the bills of the two birds in the pictures below?  And that the uppermost bird is holding onto a brown object at one end of the squiggle?  (You can click on the images for slightly larger versions.)

 

Close-up of the uppermost bird:

 

I know this is difficult because you don't have a lot to go on, but do you have any guesses about what the white squiggles might be?

The next day I went out and dug around myself to figure this out.  But I'll give you a chance to think about it, so I won't reveal the answer until tomorrow.

For now I'll leave you with two more pictures of meadowlarks — one stretching its wing and tail (showing the white outer tail feathers), and the other with a meadowlark in a crouched position (revealing that incredible yellow throat).

 

 

Rafting

At Doran Beach late this afternoon, I went to pull a tangle of seaweed off a larger piece of drift kelp so that I could confirm the identity of the kelp.  In the process of doing so I couldn't help smiling when I revealed this little sea star holding onto the kelp.  It's interesting to see them in situations like this, because you can then imagine how they could "raft" around, using kelp or other seaweeds to disperse to different sites along the coast.

 

The kelp is Pterygophora californica, sometimes known as Walking Kelp.

The sea star is a bit more challenging.  Here's a close-up:

 

It looks like a species of Pisaster to me, with five fairly stubby arms.   There are 3 species of Pisaster in this area.  The habitat — rafting on kelp — probably isn't that useful as a clue to the species identification because I'm guessing all three Pisaster species could end up in that circumstance.

This individual was very small, ~5 mm across.  And it looks very similar to juvenile Ochre Sea Stars (Pisaster ochraceus) that we're familiar with in the rocky intertidal zone on the outer coast (see photo here).  But when I thought about it, I realized that I wasn't completely sure how easy it would be to tell the three species of Pisaster apart at that size.  They're very easy to separate as adults, but I don't know when they start to differentiate.  Does anyone?  It would be fun to know!  At what size do Short-spined Sea Stars turn pink?  When do Giant Sea Stars develop blue rings?

Here are links to Ochre Sea Star (Pisaster ochraceus), Short-spined Sea Star (Pisaster brevispinus), and Giant Sea Star (Pisaster giganteus) adults.