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Tuesday, March 31, 2015

Blue beaches


Okay, okay — I know I've written about By-the-wind Sailors (Velella velella) a few times already in March.  But I haven't seen this many wash ashore at once since 2006, so I'm posting a few pictures to document this event and to record a few notes.

I wrote about small Velella (only 1-5 mm long) washing ashore on 24 March and 27 March.  Local beaches are now blue with larger Velella, many 30-40 mm long, and the largest ~60 mm long.

Here's another image showing the density on 31 March 2015:



The next two pictures are close-ups to document the sizes present.  


Below, scan carefully for very small Velella, too



I can't imagine how many Velella have stranded during the last few days.  Their extreme density makes counting a challenge.  



I had started to wonder if it was common to see such a wide range of sizes at one time.

Last summer I posted a couple of graphs: one showing records of Velella sizes, and another illustrating a prediction of Velella's annual cycle of growth and reproduction.

Here's the first graph (below) from Bieri (1977).  The vertical solid lines show the lengths of Velella recorded at different locations in different years.


Note that it looks like it's relatively unusual to have very small Velella (under 5 mm) and larger Velella present during the same event e.g., the lines in the middle of the graph hardly ever reach the bottom, and the short lines that start at the bottom don't extend very far up.


The distribution of sizes we're seeing on the beaches at this time match Bieri's prediction fairly well (although the timing might be different).  Check out the next graph below.  The purple line represents abundances of different sizes.  For February, he predicts lots of small Velella (10 mm and under), good numbers of 20-30 mm Velella, and some up to ~40-45 mm.  That was the situation here in early March.  Now we're seeing more Velella in the 30-40 mm range, and the largest in the 60 mm range, so even though we're turning the corner into April, perhaps we're transitioning into his March prediction.



Are you seeing Velella in your area?  How many?  What sizes are you seeing?  Although it can be sad to see so many wash ashore, it's also an opportunity to contribute to what's known about their life history.


Graphs above from Bieri, R.  1977.  The ecological significance of seasonal occurrence and growth rate of Velella (Hydrozoa).  Publ. Seto Mar. Biol. Lab. 24: 63-76.

Monday, March 30, 2015

Silver seas


Mixed swell off Bodega Head on 30 March 2015.  Wave height ~11 feet, northwest winds ~18 knots (20 mph), with gusts to 25 knots (28 mph).

Sunday, March 29, 2015

Rewind

At the end of the day, I looked back to see this beautiful male harrier perched in the grassland on Bodega Head:


The photo above was actually one of my last pictures.  When I'm reviewing pictures, if I think the best ones were taken last, sometimes I start with the final image and then step through them in reverse.  This turned out to be a fun process for these harrier pictures today one that I'll share with you.

The harrier had just caught something and was starting to eat it.  I was too far away to identify the prey, but I decided to take pictures anyway.  

Here's the next picture I encountered:


Hmmm...was it eating a snake?


On to the previous image in the series, and another clue:


Hmmm...at the harrier's feet you can see the prey's head, but is it a snake?


Rewind to clue number three (this one will give it away):


Aha!  Legs!  Not a snake!  A lizard!


The harrier used its bill and feet to manipulate the lizard.  In the next image, he is picking up the lizard with his talons.  (Click on the image for a larger version.)


[It's likely this was an alligator lizard.  For an example, review the post from 10 April 2014.]

Harriers are known for having a broad diet, including small mammals, birds, reptiles, amphibians, and insects. 

Although their prey might not feel the same way, I'm so glad to be seeing harriers again on Bodega Head.  For a while, it seemed like sightings of them had become uncommon.


Friday, March 27, 2015

How many tiny sails?

I know I just wrote about tiny By-the-wind Sailors (Velella velella) a few days ago.  I have to post about them again because I don't think I've ever seen so many of this size, and it seems worth documenting.

Here's a picture showing a variety of sizes with a ruler for scale.  The Velella on the left is the more typical size that you "expect" to encounter on a beach.


Below is the same picture, but it's a close-up of the left side of the ruler:


Now you can see the smallest of the Velella, just a couple of millimeters long.  They looked like this for almost the entire length of the beach that we walked, about 3/4 mile.

I know they were probably variable along that stretch of beach.  But if we used this picture just to come up with some sort of estimate then there were 25 tiny Velella/10 cm or 2.5/cm, and there are 160,934 cm in a mile, so there would have been ~400,000 tiny Velella washed up on a mile-long section of Salmon Creek Beach tonight.  No wonder I kept saying, "Wow" as we walked along next to the receding waves.
 

Thursday, March 26, 2015

Sipping sphinx

Some rapid movement in the shrub outside of my office window caught my eye today.  It had the look of a hummingbird at first, but with a better view I realized it was slightly smaller:


This is the first White-lined Sphinx Moth (Hyles lineata) I've seen on Bodega Head proper.  (I wrote about one in the village of Salmon Creek last summer see post from 30 July 2014.)

The moth was actively nectaring from the Myoporum flowers.  In the photo above, can you see its long proboscis arching down towards the leaves?

Here's another view, where you can see that the needle-like proboscis has been inserted into the center of a flower:


Below you can see the moth with its proboscis partly furled.  (I'm not sure if it was furling or unfurling it.)


I think you can tell that I was pretty impressed with the length of this moth's proboscis.  I was taking these pictures while the moth was at least 15-20' off the ground, so I didn't know at the time that I had captured the moth with its proboscis extended.  The next picture was actually one of my first pictures.  When I first looked at it, I thought I might be seeing the proboscis, but I wasn't certain, because it was so long!  Now that you're used to what the proboscis looks like, can you find it in the picture below?


I'm guessing you found the proboscis, but here's the same picture with arrows to confirm (below).  The top arrow points to the location of the moth's head, near the intersection of its forewing and antenna.  The bottom arrow points to the lower end of the proboscis where it's inserted into the flower. 


I learned something interesting about White-lined Sphinx Moths today.  It sounds like they fly year-round in southern California, and they colonize sites to the north every year.  So does this mean that this individual flew up the coast and recently arrived in northern California?  Recently, there has been a significant northward movement of Painted Ladies.  I wonder if other insects have been taking advantage of favorable weather conditions for moving north, too?

Wednesday, March 25, 2015

Humbled by a bubble -- Part 2

A few years ago, I wrote about some colorful bubbles in the intertidal zone (see post on 19 April 2012).  I had wondered if they might appear under certain conditions.  I'm starting to think that the best chance of seeing them is during spring upwelling, when there are high nutrient levels in the water.

I encountered something similar on 24 March 2015 in a mussel bed:


There was an amazing diversity of colors in the bubbles among the foam.



And as before, I was fascinated by the rapid color changes and motion in some of the bubbles:

You can follow the movement of an "eddy" in a green bubble in the next two pictures.  (The images were taken ~1 second apart.)



And watch how the large bubble at the bottom of the next picture changes over ~14 seconds.




A wave came and washed this foam away...otherwise I could have watched these bubbles for a long time!

Tuesday, March 24, 2015

Just learning to sail

I was leading a field trip today when we encountered thousands of By-the-wind Sailors (Velella velella) washed up on the beach.  There were a variety of sizes, so later on I lined up some examples for comparison (see below). 

How many Velella do you count in this picture?


There are nine Velella in the photo above.  The largest (on the right) is about 37 mm long.  The smallest (on the far left, and barely visible) is only 3.4 mm long.

I was impressed with the number of very small Velella.  I spotted quite a few that were ~5 mm long.  And although hard to see, a few that were only ~3 mm long.  Below are close-ups of each.



So here's the crazy part.  I brought in a few pieces of driftwood with pelagic barnacles.  When I put them in water and looked under the microscope, I noticed a few things pop to the surface that I thought were bubbles.  I couldn't help saying, "Wow!" out loud when I realized they were very tiny Velella the smallest I've ever seen.

These Velella were just starting to form their sails (the ribbed, flexible feature at the top).  They don't have visible floats yet.  You can see the colorful rim of their mantle, and just a few tentacles hanging below.


So how small were they?


Only 1 mm long!


I'm including one more individual that was even slightly smaller:


Can you imagine these tiny Velella sailing on the high seas during a big storm?

You might have noticed that the 3-mm Velella in the third photo of this post did have a float.  So this means that the float is formed when Velella is between 1-3 mm long.

It would be hard to find a 1-mm long Velella in the field.  But I'm guessing you could find a 3-mm long Velella.  Here's one more photo the largest and smallest Velella in the field today:


Sunday, March 22, 2015

1000!

This is my 1000th post!  It's a little hard to believe.  

I knew this day was on the horizon, and I had been contemplating what type of photo might be appropriate for the occasion.  To be honest, I wasn't coming up with any ideas that I was happy with.  

And then Eric thought of a photo mosaicI could create a picture made up of 1000 images from previous blog posts.  That sounded like a great way to celebrate, and luckily there's software available to help.

I think you'll be able to tell that the first mosaic is an aerial view of Bodega Head.  You can click on the image for a slightly larger version.  But because it's so much fun to scroll around and reminisce about all of the individual photos, I've uploaded a full-size version of this mosaic to Flickr.  Click here to download a full-size version of the Bodega Head mosaic.  When you're on the Flickr page, use the download button in the lower right corner and choose "Original Size."


The Bodega Head mosaic came out well, and included some nice photos, but the original image lacked certain colors, which meant some blog photos were left out.  So I chose another image that included warmer tones (oranges and pinks).

The next mosaic is a sunset from Bodega Head.  It's a little abstract, but very pretty, don't you think?

And once again, if you want to have fun checking out close-ups of the individual pictures making up the mosaic, you can access the full-size version on Flickr.  Click here to download a full-size version of the sunset mosaic.



And I couldn't resist including one more mosaic.  Eric suggested a good title for this one  "eyeNaturalist."


When the final rendering was revealed, I wasn't sure what to think at first, with my eye surrounded by lots of figures and text, along with all of the plants and animals and landscapes and seascapes.  Then I thought that it was quite appropriate.  I'm always looking for interesting things, trying to learn more about them, and thinking about the best ways to share information.  This isn't a bad visual representation of that process!

Click here to download a full-size version of the eye mosaic.

And remember, all of the images in these mosaics are from previous blog posts.  It turns out that I've used a little over 4,000 images on the blog so far, so there were plenty to choose from!


It took me longer than expected to make these mosaics, so it's pretty late (at least for me).  However, at this significant milestone, I wanted to express my thanks to all of you who read this blog and discuss natural history with me.  It's all more meaningful than I can say.

I listened to an interview with Mary Oliver today.  In it, she said, "Attention is the beginning of devotion."  I've been trying to pay attention to the natural history of Bodega Head for a little over a decade now.  I know learning about it is endless, but after 1000 posts, I think I can say I am devoted to it.   ;)  So on to 1001!

Saturday, March 21, 2015

Slender-billed Nuthatch

In 2013, the American Ornithologists' Union voted on whether White-breasted Nuthatch (Sitta carolinensis) should be considered several species rather than one.  For example, whether there should be a Carolina Nuthatch, a Rocky Mountain Nuthatch, and a Slender-billed Nuthatch.  (The birds we encounter on the West Coast would be in the third group.)

The A.O.U. voted against the proposal, citing the need for more data.  For now, these groups of nuthatches remain subspecies, and they vary in plumage, bill shape, and vocalizations.  

Now when I see and hear White-breasted Nuthatches, I pay a little more attention.  It's a chance to consider how they might vary, and it's also an opportunity to contribute to what's known about them in different parts of the country.

Here are two views of a male White-breasted Nuthatch in Santa Rosa on 14 March 2015.


Examples of things to look for: the length of the bill, the amount of white in the face, the width of the black crown, and the amount of black in the blue-gray feathers.


And you can listen to this male singing, too.  I should have also tried to record the call notes (which vary among the subspecies), but I have a brief recording of his song.  [By the way, I haven't heard a discussion about why the call notes would differ more than the song.  Nuthatches do tend to call a lot, and they don't sing that often.  Could that be part of the reason?]

Pardon the background noise, as this recording was made with my camera.  Remember to turn up the volume of your speakers.



If you're interested, you can read more about differences in the subspecies of White-breasted Nuthatches in this article by Steven Mlodinow

Friday, March 20, 2015

All lined up

Some of you already know how much I like nemerteans, or ribbon worms.  We've been hoping to find this species for a while so we could introduce it on the blog.  It's relatively uncommon though, so you don't see it as often as you'd like.


Six-lined Ribbon Worms (Tubulanus sexlineatus) live in transparent tubes under rocks and among algae and mussels.  This one was photographed out of its tube for the sake of highlighting its wonderful patterning.

In the picture above, that's the head on the left side.  There's one narrow white band near the leading edge, and then at least four thicker white bands after that.  Following these first five bands, the white bands become much closer together (see images below).

The "six lines" for which this species are named are the very narrow white stripes running down the length of the body from the head to the tip.  Several are visible on the dorsal (upper) surface, and a few are on the ventral (lower) surface.

When stretched out, this ribbon worm is quite long I estimated about 30 cm.  (Some individuals may reach 1 meter or more!)  When looking at the center of the ribbon worm, at first I had trouble identifying the upper and lower surface.  I could see a difference one had white speckles and the other was more uniformly brown (see next picture), but I wasn't sure which was which. 



I had to go back to the head and trace the upper and lower surfaces, and finally figured out that the upper surface is the speckled one.  Now you can identify both in the next two pictures, even as the ribbon worm is twisting:



Many books and images on the Internet show the head and middle portion of Six-lined Ribbon Worms, but I've hardly seen any pictures of the posterior end.  Here's a picture of the all white tip!


I'm including one more picture of this beautiful ribbon worm (although it would be easy to show many more!).  It's fun to think about the color patterning of this species.  Why does it have so many stripes and bands?  Does it help blend in with light and shadow?  Is it distracting to potential predators?  Is it disruptive coloration (breaking up the outline of the animal to confuse predators)?  Do you have other ideas?


Wednesday, March 18, 2015

Heralding the arrival of spring


I'm glad that Michelle and Kyle mentioned that you can find Trillium near the side of the road in Occidental.  I stopped briefly to take a few pictures on 18 March 2015.

This is Western Trillium or Western Wakerobin (Trillium ovatum).  Having spent most of my time at the ocean, I don't have a lot of experience with them.  I read that while most are white when they start flowering, they fade to a deep-rose color.

Here are two more examples of flowers that are further along:



"Trillium" refers to the flower parts coming in sets of threes (see below).  I wondered about the name "wakerobin."  I found a few references online that explained the name derives from the fact that these flowers bloom at the same time that robins are heralding the arrival of spring.



This is a good time of year to see Trilliums catch them if you can!