Like mother...

...like pup.

 

Harbor Seals resting in shallow water below the bluffs on Bodega Head on 2 May 2013.

 

Singing in the parking lot

On 11 April 2013, I stepped out of my car in the Bodega Marine Laboratory parking lot to hear a vireo singing.  That's the first time that's happened in 9 years of working at the lab!  I started looking around in the shrubs and soon found the bird responsible for the song:

 

Although Cassin's Vireo (Vireo cassinii) is described as a "fairly common summer resident and fall migrant" in Sonoma County (Bolander and Parmeter 2000), it's considered a rare migrant on Bodega Head.

In both of these images, look for the bold white "spectacles," gray head and face, olive-green back, white underparts with hints of yellow, and two white wing bars.

 

The vireo was foraging among the Myoporum shrubs.  It caught at least one moth and a caterpillar (see below).

 

 

In the image above, the vireo is holding an inchworm against the branch with its right foot.  Initially the vireo had picked up the caterpillar with its bill, but then it placed it on the branch and held it there before eventually picking it up again and swallowing it.

Here's a quick trivia question related to this vireo's name.  It honors John Cassin, a 19th century ornithologist who wrote one of the first major accounts of birds in the western U.S.  Do you know how many other birds were named after him?  That is, how many other birds can you think of with "Cassin's" in their name?  The answer is below the next image.

 

Answer: Four other birds were named after John Cassin: Cassin's Auklet, Cassin's Finch, Cassin's Kingbird, and Cassin's Sparrow.

 

Small but powerful

On Saturday morning we were walking on the southern end of Bodega Head when a distinctive silhouette flashed by on the distant horizon — a medium-sized mammal, long and slender, low to the ground, with a long tail held up high.  I was both excited and disappointed, for I had been hoping to see this species during the last couple of weeks, but at the time I only had a short lens with me (limiting my picture-taking capabilities).

As we got closer to the spot where we thought the mammal had been, we started watching more carefully among the shrubs and flowers.  It took a few minutes, but then we got lucky and spotted it.  It's in the picture below.  Can you see it?

 

Here's a closer view as the animal rose up (like a periscope) and looked to the side:

 

And another showing a head-on view, the short front legs, and the long tail with the black tip (held out to the right).

 

This is a Long-tailed Weasel (Mustela frenata). I must admit, although I'm not prone to naming "favorites," I love every opportunity to observe this species.  And this individual was actively hunting right in front of us.

It kept diving into the shrubs and then popping up somewhere new.  And finally it emerged with prey!

 

Long-tailed Weasels are carnivores, primarily pursuing small- and medium-sized mammals such as voles, mice, and pocket gophers.  But they're known to be generalists and may switch to alternative prey when it's available.  Although Long-tailed Weasels are relatively small (~11-20 inches long, including the tail), they can subdue sizable prey.

I'm actually not 100% certain what this weasel caught.  In the field, we wondered if it was a young pocket gopher, but after reviewing the pictures I'm not sure.  I need some help from folks who have more experience with West Coast mammals!  Here are several views of the prey (below).  If you have thoughts about its identity, it'd be great to hear them.

 

 

 

 

May and June seem to be the best months to see Long-tailed Weasels on Bodega Head.  Adults are probably feeding young at this time of year, so they are out during the daytime a bit more than usual.

Long-tailed Weasels aren't common, so it's a lucky day when you see one.  But keep an eye out for a narrow brown back bounding among the grasses, or a black-tipped tail disappearing between the shrubs.

 

 

ADDENDUM (13 May 2013): Okay, I've heard back from a few people, and the verdict is that the prey item is a vole.  Although it looked big in the field, the legs are narrow, the feet are small, and the ears are large — all characteristics pointing to vole rather than gopher.  Thanks to everyone who provided feedback and assistance!

Mesmerizing

 

Sometimes I'm tempted not to write anything at all and to let these pictures and organisms speak for themselves.  This is one of those times, but this little sea anemone has quite a story!  It's hard not to be mesmerized by the delicate pink tentacles and the white striping pattern.  (The disc of the anemone is ~1 cm across.)

At first this species looks very similar to a more common anemone, Epiactis prolifera.  However, note that at least two of the white stripes continue over the edges of the mouth in the center of the disc (see below).

 

The texture and coloration of the column is even more helpful when separating this species from Epiactis.  These aren't great pictures, but you can still see that unlike Epiactis the column of this anemone is rough or bumpy rather than smooth and it lacks stripes. 

 

 

Both the oral disc striping pattern and the column characteristics confirm this as Aulactinia incubans.  This appears to be the first record of this species for Bodega Head.  Indeed, this species is probably rare throughout California, being a more northern species, with The Light and Smith Manual saying only this: "Described from San Juan Island, Washington; occasionally found on the coast north of Santa Cruz in protected low-intertidal areas such as under overhangs..."

The species name, "incubans," refers to a fascinating reproductive behavior.  This anemone broods its young internally then releases fully tentacled young through pores at the tips of the tentacles!

 

We've found two individuals locally during the past year, with the most recent sighting just a few weeks ago.  Here's a picture from the field:

 

Out for a stroll

A couple of weeks ago, Eric spotted this Reticulate Button Snail (Trimusculus reticulatus) out for a stroll.  Note the circular shell and the network of radiating lines.

 

We were very surprised for a number of reasons. These marine pulmonate snails are found in crevices and shaded overhangs in the rocky intertidal zone.  They're often in gregarious clusters (see next image), and are known to be relatively sessile (i.e., they don't move very much).

 

In our experience it was unusual to encounter a single individual, especially one that was out walking around!  In fact, we'd never seen the oral lobes extending in front of the shell before.  The lobes are an unusual shape (unlike the true tentacles of other snails), so we took some time to study them and to wonder about how they would be used.

 

I haven't been able to find anything about how the lobes might function at low tide.  At high tide the snail uses them for feeding.  Reticulate Button Snails are filter-feeders.  They produce mucous nets that collect phytoplankton from the water and then gather the nets with their oral lobes.

A few years ago I was also surprised when I encountered a very large aggregation of this species depositing eggs.  When I looked closely I noticed many egg masses adjacent to the shells.  (Note that often the reticulate pattern for which the species is named is eroded or overgrown.)

 

Intertidal Invertebrates of California says, "The eggs masses are gelatinous and petal-like, and are attached in rosettes on the rock around the animal that laid them.  Egg deposition occurs in April at Tomales Head [sic]..."

I took these pictures in July on Bodega Head:

 

You'll probably notice that some of the egg masses are white and others are brown.  I'm not sure what's going on with the colors, but am wondering if the brown masses are older?

 

Back to the animal we saw in late April.  It's hard not to wonder about its story.  Will it find an aggregation to join, or will it start one of its own?

 

Find the fish

In late April, I photographed this fish resting between two Ochre Sea Stars.  I'm not sure what type of fish it is, but it was fun to see how well it matched the colors and patterns of the sea stars.

 

Here's a close-up of the head:

 

If you can identify the fish, let me know!

 

Take five

Dwarf Brittle Star (Amphipholis squamata), found in the low intertidal zone on Bodega Head on 28 April 2013 and photographed under a microscope.  It was ~15 mm across.

 

 

 

 

 

I could have stopped with that series of five images, but I was fascinated when I caught a brief glimpse of the underside of the brittle star.  Here's a close-up (below).  The mouth is the dark cavity in the very center of the disk.  But what's perhaps most interesting in this particular image is the white scale with a single pore to the left of the mouth.

 

That modified scale is the madreporite (or sieve plate).  Water is pulled in through the madreporite and enters the water vascular system which powers the tubefeet.  In sea stars, the madreporite is on the aboral surface (opposite the mouth) — for an example, see the salmon-colored spot on the Ochre Sea Star in the photo below. 

 

But in brittle stars, the madreporite is on the underside, adjacent to the mouth.  It's not often as visible as it is here, so this is a nice illustration of one of the differences between a brittle star and a sea star.

Here's another view with the madreporite in a slightly different position.  Can you find it?

 

The madreporite is in the lower right corner (remember it's about halfway between the mouth and the outer edge of the disk).  [If the brittle star was a clock, the madreporite is located between the arm that points to 3 o'clock and the arm that points to 6 o'clock.]

Although this brittle star was small, it revealed a significant lesson!