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Thursday, January 30, 2014

The best-laid planulae

I have a small side project in which I'm trying (slowly) to learn and document the local hydroids.  I was photographing a common species this week Eudendrium californicumbecause it's noticeably reproductive at this time of year.

These wonderful colonial marine invertebrates are often visible in the low intertidal zone on rocky shores.  They appear plant-like at first, but remember that they're related to sea anemones (and jellyfish and corals).  Those flower-like units have tiny mouths surrounded by stinging tentacles waiting for prey to swim by too closely.


The bright orange clusters in the background are reproductive units.  I zoomed in on one cluster to take a picture and my eyes opened wide when I realized that a larva was hatching at that very moment!

In this species, the fertilized eggs are retained in these clusters and they develop into planula larvae that look like small, pink tear-drop shaped worms (but they're not worms!).  The planulae hatch and are free swimming for a short time before settling onto the bottom and undergoing metamorphosis into new hydroid polyps that will continue developing into larger, branched colonies like the one you see in the image above.

It didn't take very long for this planula larva to hatch, so today you (yes, you!) get to see this process in pictures.


For orientation, most of the developing embryos are orange.  There's one blob that's more pinkish in color near the center of the image (it's also slightly smaller).  That's the one you're going to watch through this series of pictures.  If you look carefully, you'll see that it's emerging from a clear capsule.  In the picture above, the pink larva is half outside and half inside the capsule.  Okay, here you go:


Fun, right?  

One more image, pulled back a little, that shows the entire hydroid polyp with a large cluster of developing embryos, and the newly hatched planula larva swimming away.  Good luck, little one!
 

Wednesday, January 29, 2014

What's on that olive?

Recently I was taking a few pictures of olive snails at Dillon Beach.  Although I've mentioned them before, I thought it would be nice to show a side-by-side comparison of two local species, Purple Olive Snail (Callianax biplicata) and Zigzag Olive Snail (Callianax pycna).  Can you tell which is which in the image below?


The Purple Olive is on the left, Zigzag Olive is on the right.  Along with the difference in coloring and shell pattern, compare their overall shapes (imagine if you were to draw an outline of each) and especially their spires (the whorls at the tops of their shells).

Olive shells are generally very smooth (they're often described as "lustrous").  But as I was picking up various Zigzag Olive Shells for the picture I encountered one with a rough patch (see below) that caught my attention.


Do you have a guess about what the rough patch is?  I thought I knew, so I kept on looking at other shells with the hope that I could confirm my suspicion.  Warning: I'll reveal the answer in the next photo.



I was fortunate to find a second snail with a barnacle shell still attached!  The rough patch on the first shell is the basal plate of a barnacle.  

The picture below shows the same snail from a slightly different angle so that you can see both the barnacle shell with its wall plates still intact and a second barnacle with only the basal plate remaining.


I've seen quite a few olive snails, but I think this is the first time I've noticed barnacles growing on them.  Has anyone else observed this?  Eric's first thought was that it makes sense given that olive snails live in sandy environments and that barnacles are looking for hard substrates to grow on.  The snail shell offers the barnacle a resource that may be in short supply.

I was surprised at the size of the barnacles relative to the size of the snail — they seemed quite large!  It made me wonder if the barnacle would have any impacts on the snail.  Would it change the water flow?  Would it affect maneuverability?  Because olive snails are sand burrowers, would the barnacle attract undue attention (from predators) by increasing height and extending above the surface of the sand?  Would there be any benefits to having a barnacle on your back?

Tuesday, January 28, 2014

Rhythm and Blues, or Rumba?

This might be a firsta post without a picture or an audio file!  But I have to share this video.  It made me laugh out loud, and I hope it does the same for you.  And even though this is an eastern bird, there *is* a California connection in fact, a very local one!  First the video (and then come back and read more):

https://www.youtube.com/watch?v=UEISiCmjwH8

I've seen American Woodcocks (Scolopax minor) moving like this when I lived in Massachusetts.  But I hadn't seriously looked into whether anyone had researched the unusual motion.

After watching the video, I started reading about it and noticed a reference to this paper:

Marshall, W.H.  1982.  Does the woodcock bob or rock and why?  Auk 99: 791-792. 

Perfect.  I downloaded the paper and was shocked to see that the author, William Marshall, lived on Oakmont Drive in Santa Rosa, CA!  William Marshall observed woodcocks in Minnesota and described the motion like this:

"As the bird slowly walked about, its head and neck remained on a level plane, but its body was almost continually moving back and forth, best described as "rocking." A line between the neck and dorsal feathers was obvious, because, while the body moved, the head did not. One foot was lifted high then placed down ahead with the weight on it; the other foot was lifted so that only the tips of the toes were in contact with the ground."

He argues that the motion should be called rocking rather than bobbing or teetering to distinguish it from the motions of American Dippers or Spotted Sandpipers.  

And he summarizes four possible reasons that various authors have proposed for the rocking: 

(1) it's a "nervous reaction resulting from fear or suspicion" Marshall discounts this theory as the birds he observed were undisturbed and birds that he did see in disturbed situations did not exhibit rocking (but see #4 below).

(2) it's mimicry "of leaves being moved by a breeze" — Marshall discounts this theory because when there isn't a breeze, rocking makes the bird conspicuous; and leaf motion is more erratic and jerky than this rhythmic rocking of the woodcock.

(3) it's mimicry of "prevailing shadows" — Marshall discounts this theory because there were no shadows when he observed the rocking behavior.

(4) it's movement used when feeding — Marshall believes that pressure from the woodock's rocking foot may cause a slight response from earthworms, allowing the woodcock to detect them by sight or even sound.  He also suggests that it's possible this rocking motion initially developed for feeding may also reveal itself in stressful situations (such as being in open landscapes exposed to potential predators).

It's interesting to think about this last possible reason for the rocking motion and then to watch the video again (or just to watch it again to laugh some more).  I can see what he means by there being pressure on that front foot.  And if you've ever seen plovers "foot-trembling" on the mudflats, there are some possible similarities there.  It's just that woodcocks do it while walking, rather than while standing in place!

If you're still with me, I can't help but add one more thing.  Marshall quotes all of the different ways this rocking behavior were described in the past.  Although the video used a Rhythm and Blues tune (Tequila by The Champs), an author in 1958 said the woodcock walked in a "rumba-like manner."  Which do you think is a better match?

P.S.  I'm guessing the author who proposed the woodcock moved in a rumba-like manner was thinking of Afro-Cuban rumba, not ballroom rumba.  For one example of the former:

http://www.youtube.com/watch?v=-rJX1fpyMos


P.P.S.  Thanks to Blair for sending the woodcock video!

Monday, January 27, 2014

Shorebird flock at sunset


Mixed shorebird flock in Bodega Harbor, 26 January 2014


Dunlin, Sanderlings, Western Sandpipers, and Least Sandpipers.

Sunday, January 26, 2014

6 on the 26th!

It all started with a glimpse of a butterfly that I thought might have been a Mourning Cloak (Nymphalis antiopa).  I was at the intersection of Jonive Road and the Bodega Highway and it flew across the road and disappeared.  Well, if I wanted a better view of a Mourning Cloak, where else could I find one?  Early in the season in New England I would observe them in warm, sunny spots around willows.  I could think of several nearby sites with appropriate habitat, so I decided to make a quick stop to see if I could find a Mourning Cloak.

Once I arrived, it took a few minutes, but I was very excited to spot this handsome butterfly cruising by overhead!  It finally landed on a bare, sunlit branch.  It was a little too far away for a good picture, but I'm including it here because it's just the beginning of this butterfly story and it's my first Mourning Cloak picture from Bodega!



While starting my search for a Mourning Cloak, I noticed another species of butterfly:

Buckeye (Junonia coenia) This was the most numerous butterfly I saw today.  Sometimes it's hard to know if the same individuals are passing through an area, but I'm guessing I observed at least 12 Buckeyes in a very short time this afternoon.


And then I noticed this butterfly fluttering along the side of the road and nectaring on a yellow mustard:

I'm glad I took a closer look.  I could have mistaken this for a Cabbage White.  But note the dark gray scaling bordering the veins on the undersides of the wings.  This is a Margined White (Pieris marginalis)I've also seen it called a Veined White.  Since I haven't shown this species on the blog before, here's one more picture:



And then I looked behind me and just barely saw this butterfly spread out among the leaves:

Not a great picture, but you can still identify this as a Red Admiral (Vanessa atalanta).


What next?  I scanned some of the flowering mustard again and spotted this species:

Mylitta Crescent (Phyciodes mylitta)


Okay, call me crazy, but I couldn't help wondering, can I find 6 species of butterflies on January 26th?  I could think of at least one more species that I might be able to find in this area given these conditions and the other species I'd seen so far.  I was near a sunny woodland edge with some low wet spots.  The species I was thinking of often rested on tree trunks, so I started scanning.

I didn't find it on a tree, but one flew by and eventually landed on a blackberry leaf.  Yes!

Satyr Anglewing (Polygonia satyrus) just glowing!


And now you're going to think I'm even crazier.  I was kicking myself that I hadn't planned my day differently.  I'm pretty sure I could have found several more species near the coast (Monarch, and one or two ladies?).  Next time.

Saturday, January 25, 2014

Gelatinous assortment

I always have mixed feelings about finding gelatinous animals washed up on the beach.  They belong in deeper water and it's sad to see them pushed up onto the sand by the surf.  But it's also an opportunity to learn about these animals that we wouldn't otherwise get to see unless we were on a boat or diving under water.  And it's a chance to document which species are present in nearshore waters right now.

Here are a few species washed ashore on Salmon Creek Beach after yesterday's big waves.


Representing the Cnidaria

A large purple Moon Jelly (Aurelia sp.)

and

A Giant Bell Jelly (Scrippsia pacifica)


Representing the Ctenophora

 
A small Sea Gooseberry (Pleurobrachia bachei)


Representing the Mollusca

The gelatinous pseudoconch of the pelagic snail Corolla spectabilis


I've written about all of these species before, so if you'd like to learn more about any of them, click on the appropriate name: Moon Jelly, Giant Bell Jelly, Sea Gooseberry, Corolla spectabilis.
 

Friday, January 24, 2014

West swell

Just a few quick pictures of the waves off Bodega Head today.  West swell, 8-10 feet (with some larger sets), and a southeast wind blowing at ~10-12 mph.






Thursday, January 23, 2014

Dusk bath

Several times during the last few weeks we've encountered Bewick's Wrens (Thryomanes bewickii) taking dust baths along trails at dusk.

Tonight I had a funny encounter with one.  I didn't have a picture for the blog tonight.  I had gone for a quick walk after work and was almost back to the car and was beginning to wonder what I was going to do about the blog.  Would I have to skip a night?  And then this little wren scooted out onto the trail and started taking a dust bath.  But it saw me and flew right back into the shrubs.  No time for a picture.  

I wondered if I stayed very quiet and motionless if it would come back out again.  I waited and waited — no wren.  Then I looked away, wondering if I should wait any longer, and when I looked back, the wren was there on the trail taking a dust bath!  I raised my camera to take a picture and it flew off.  Was there any chance it would return a third time?  I waited and waited.  And what do you know, one more time the wren dashed out, landed in the path, and started fluttering around on the ground.

It was almost dark by this time, and the wren was some distance away, so this isn't a great picture.  But oh, well, it's still an interesting story and an introduction to dust bathing in wrens!



Then I had lots of questions.  For example — If a bird takes dust baths, does it take water baths, too?  Is there a benefit of one over the other?  How many species of birds take dust baths vs. water baths?  Do birds take more dust baths in drought years?  The other day I watched a bobcat rolling in a warm patch of bare soil — how common are dust baths in other animals?  Did people get inspired to take bark-chip baths by watching birds take dust baths?  ;)


I did a tiny bit of reading about dust bathing behavior in Bewick's Wrens and learned a few facts:

- They take dust baths in loose, fine-grained soil or mud.
- They most often take dust baths at dusk.
- Dust baths are thought to control the accumulation of lipids on their feathers (which may affect insulation) and possibly to control parasites.  The latter is apparently more controversial in that it hasn't been proven.  It has been hypothesized that dust may control parasites by suffocation, dislodgement, or abrasion (followed by desiccation). 

Wednesday, January 22, 2014

A quiet moment


One of the things I really like about the blog is that I can share pictures that you wouldn't necessarily see in a field guide.  Some of these images don't show all of the important characteristics of a species, but instead they illustrate an interesting behavior or capture a special moment.

This is a Snowy Plover preening its feathers on the tidal flats in Bodega Harbor on 19 January 2014.  In trying to identify why I was attracted to this photograph, I came up with a few different reasons. 

I love habitat and seasonal associations.  The purple color on the mudflats surrounding the plover is a good representation of late afternoon light in winter.  So this image is just a classic picture of a Snowy Plover in one of its preferred winter habitats (they also like sandy beaches).

And I love knowing that animals can be left undisturbed by people.  Even a bird like the Snowy Plover, that lives in places that so often intersect with the hustle and bustle of human activities, can still find a place to stand quietly and preen its feathers after taking a bath in a shallow pool.

Tuesday, January 21, 2014

Tale of a trailing tail trail


Another interesting track in the dunes.  Sadly, this one was harder to photograph, and I was working at the time, so I only took a few shots which didn't come out great.

I'm not sure whether there's enough here to identify the animal responsible for these tracks.  See what you think.  It looks like there's a tail trailing behind the animal, creating a gentle wave-like pattern through the middle of the track. 



And it appears that there are feet pushing off to either side of the tail drag.


 
Here's another view from a different angle.  Do you have a guess?



I'm wondering about lizard.  (Claudia, can you help?)  My first guess was Northern Alligator Lizard, because they're the most common lizard in the Bodega Dunes.  But I searched for pictures of alligator lizard tracks on the Internet and found a few images that don't look like this.  

Then I wondered about Western Fence Lizard, since they're uncommon to rare in the Bodega Dunes.  But I couldn't find good pictures of their tracks.  So for now I guess I'll wait to see if anyone has more experience with their track patterns and can confirm or deny that these are a possible match. 

For the record, since I haven't shown this species yet, here's the only Western Fence Lizard (Sceloporus occidentalis) that I've photographed on Bodega Head.  This picture is from 24 June 2006.



To truly appreciate the beauty of this lizard, I zoomed in on the scales (this also allows you to see a hint of the "blue belly"): 


Monday, January 20, 2014

Bounding


A nice set of tracks in the Bodega Dunes.  Each footprint was very small — I didn't measure at the time, but I'd estimate less than 1 cm long. 

Note that the prints occur in sets of four with gaps in between (follow them diagonally from the lower left corner to the upper right corner of the picture).  This pattern indicates that the animal was bounding across the sand, rather than walking.

Here's a closer view of two sets of tracks (below).  Although subtle, you should be able to see that in each set, two prints are slightly smaller than the other two.  Which ones are smaller the two in front that are side-by-side, or the two in back that are one-in-front-of-the-other (a bit offset)?


It's the two in back that are one-in-front-of-the-other that are smaller — and these are the front feet.  When bounding, the animal planted its front feet first, and then placed its hind feet ahead of the front feet.

The individual toes are visible in the picture below (there should be five toes, but they don't always register in the sand).


You can probably tell that this is a small mammal.  I'm guessing it's either a mouse or a vole.  I haven't learned to tell their tracks apart yet, but based on the bounding behavior, I'm leaning towards mouse (Peromyscus sp.).  What do you think?

Sunday, January 19, 2014

Warm weather emergence

It looks like the warm weather this past week triggered the emergence of some local moths.  There were several species flying around our house in Sebastopol tonight.  I'll show just a couple below.

Moths force you to look at patterns.  This next series of four images may be the same species of moth.  You probably won't have any trouble believing that when comparing the first two pictures.  It's the third and fourth pictures that are more challenging.  But if you look very carefully, there are enough overlapping elements (spots and stripes) that I'm leaning towards thinking all four are the same species, even though they look quite different at first!






And here's one more example showing what I think is a different species than the first one documented above (although I'll admit, frustratingly, that I'm not 100% certain yet!).  Note that in the two individuals below, the dominant colors are different, but the striping patterns are similar enough that I believe they're the same species.




I haven't had a chance to work on the identifications of these moths yet.  If you know what they are, feel free to write.  I'll update this post if I hear back from anyone or work out the identifications myself. 

ADDENDUM (22 January 2014): Well, my first guess is that these are Oak Winter Highflier Moths (Hydriomena nubilofasciata).  I actually wrote about them last winter, but these individuals look quite different than the ones I photographed in January 2013 (see those pictures here).  If I'm right, this is one of the most variable species I've seen!

Saturday, January 18, 2014

Settling in for the night

This is going to be an identification challenge, but I figure it's more fun for you to try first than to be told outright.  To set the scene, I took this photo around 5 p.m. on 18 January 2014.  These birds were flying over the salt marsh between the Bodega Bay Post Office (or Bodega Harbour Yacht Club) and Doran Beach, adjacent to what's now called the Bird Walk Coastal Access Trail.


I liked all of the different positions of the birds in the picture above.  And I hope you sensed that they were flying quickly and somewhat erratically.

A few minutes before, when the light was a little better, I did manage one picture of a couple of birds that might help you with the identification:

 
I won't be surprised if this is still difficult.  These aren't great pictures!  But it's a fun story, so I can't help showing them.

These are American Pipits (Anthus rubescens).  Some time ago during a bird survey, I accidentally flushed a large flock of pipits from this same salt marsh.  It made me wonder if they roosted there at night.  I meant to go back and check, but hadn't managed to do so.  Tonight I was in the area just before sunset and noticed a very large flock of songbirds descending towards the marsh.  Pipits!  It was true!  They do roost in the marsh!

There are a number of things that amaze me about this behavior and capture my curiosity:

I've been birding for a while and have been in areas where pipits spend the winter on beaches and where salt marshes occur nearby, but I don't recall hearing about very large flocks of pipits roosting in salt marshes.  Have I just missed it?  Does it occur elsewhere?  Or is there something special going on in Bodega Harbor?

When you see pipits feeding on local beaches in the Bodega Bay area, you might see 1 or 2 birds, or maybe half a dozen or so.  But the flock I saw coming into roost was much larger.  And it appeared that birds were coming in to join the flock from different directions, i.e., that this might be a communal roost.  (I'm not completely sure about that, but it would be worth pursuing.)

I didn't capture the entire flock on film, but here's the largest number of pipits in one photo (below).  If you care to play the counting game, remember that you can click on the image to enlarge it and be sure that your computer monitor is clean!  (My count is below the image.)


On my first time through, I counted 91 birds in the photo above.  What did you get?

That's a large number of American Pipits.  Especially since the Birds of Sonoma County mentions that pipit numbers in the county have been much lower during the last 10-15 years.

Why do the pipits roost in this salt marsh?  How far away do they come from to roost here?  Do they roost here all winter, or is there a narrower window when they use this site?

I couldn't find very much about pipit roosting behavior.  There was one line in the Birds of North America that came from Burleigh's account of Georgia Birds: "A flock of about 1,000 birds that came to roost in a marshy field was restless and noisy, flying up in a loose, straggling group that circled overhead for several minutes before dropping to the ground again and settling in for the night."

I was interested in this description, as tonight the pipits would land in the marsh, then take off again and circle around, then settle and take off again and circle, then land, then take off, over and over for at least 10 minutes before they finally appeared to stay put for the night.

Here's one last picture of one of the flock's last dives towards the marsh:


It's always satisfying to learn something new and intriguing about a familiar species.  If you have stories about roosting pipits to share, please do!

P.S.  For a close-up of an American Pipit on Salmon Creek Beach, click here.

Thursday, January 16, 2014

Something about cephalopods

I was right the squid were ready to hatch!  I kept the capsules overnight and this morning when I checked on them I noticed a couple of tiny squid jetting around in the bowl!


If you look closely, you can see suckers on their tentacles, and small swimming fins on the other (dorsal) end.  

Below is another picture that shows the swimming fins.  The fins extend out to either side of the mantle (at the top of the photo).




Those of you who have been following this blog know how much I love chromatophores.  (For more about them, see the "Living Paint" post from 2 February 2013).  

So here's a photo highlighting the chromatophores in this squid paralarva.  This is the same individual as in the photo above.  But notice how large the chromatophores are now!  You can go back and forth between the photos and trace individual spots to see how much they've changed between photos.




I can't resist sharing one more picture — I don't know what it is, but there's just something about cephalopods that pulls me in.  They're beautiful, they're fascinating I could watch them all day!