Downy white

  

I ran into Laura outside of the grocery story today.  She told me a story about discovering a Turkey Vulture (Cathartes aura) nest in an old tree stump on her property recently.  It reminded both of us of the time a vulture nest was found in the Bodega Dunes.  I didn't have a great camera setup at that time, so this is Haruka Wada's photo (I think).  

If I remember right, the vulture in the photo was ~20 days old.  Back then, I hadn't seen a downy juvenile vulture before, so I was surprised to see how white it was.  I think it takes ~60 days or so before all of their black feathers come in.

Photographed in the Bodega Dunes on 24 May 2006.  (Hard to believe this was 19 years ago!)

P.S.  Thanks to Laura for the memory and to Haruka for the photo!

Octopus for lunch?

  

Octopus for lunch?  

A Turkey Vulture (Cathartes aura) feeding on a Giant Pacific Octopus (Enteroctopus dofleini) washed up on the beach on 25 April 2023.

A thorny identification

While conducting a survey on the beach yesterday (31 March 2017), we noticed a Turkey Vulture in the distance.  We could tell it was feeding on something, but couldn't tell what it was.

 

When we got closer, the vulture had flown off, so we went over to look at what had attracted the vulture's attention:

 

At first I thought it was an electric ray, but there were several characters that didn't seem right.  After doing some more research, I believe this is a Thornback Guitarfish (Platyrhinoidis triseriata) — the first I've seen.

It's especially important to note that the caudal fin (at the tip of the tail) is relatively small; the two dorsal fins (on the right side of the photo) are about equal in size; and there are three rows of prominent spines running down its back and along the tail (sorry I don't have better pictures of those!). 

Thornback Guitarfish prefer shallow water and sandy or muddy bottoms.  They are known to occur as far north as Tomales Bay.  Have you seen them in Bodega Bay, or anywhere further north?

P.S.  To compare with a Pacific Electric Ray, review the post from 5 February 2014.

 

Clothed in black

 

Today, 9 November 2016, I finally caught up with the Black Vulture (Coragyps atratus) that's been observed in Bodega Bay for the past month.  It was drinking from a small puddle in the dirt parking lot at the north end of Bodega Harbor (adjacent to the Bodega Dunes campground).

Black Vultures are rare vagrants to this area.  It looks like the closest regularly occurring population is in south-central Arizona.

Here's a nice comparison with a Turkey Vulture (Cathartes aura):

 

Note the differences in head color (gray vs. red); overall feather colors (black vs. brown); bill shape (straighter vs. more noticeably curved); and visibility of nostrils (subtle vs. obvious).

Interestingly, although the Black Vulture is slightly smaller overall, it was dominant to the Turkey Vultures.  In the picture below, note how the Black Vulture is standing upright and defending the water source, while the Turkey Vultures are low and submissive:

 

After drinking, the Black Vulture flew up to a nearby cypress tree to bask in the morning sun.  Note the "fluffed" feathers around the neck and wings (to "let the sun shine in"):

 

P.S.  The genus, Coragyps means "raven-vulture" and the species name, atratus, means "clothed in black."  So this is the "raven-vulture that's clothed in black."

Subsidy

About a week ago, while driving into work, I noticed a few Turkey Vultures (Cathartes aura) feeding in a grassland.  By itself that sighting wasn't unusual, but the exact location was a little odd — I hardly ever see vultures feeding there.  It was close to the road, so I decided to walk out to take a look at what they were feeding on.

 

I expected it to be some sort of mammal or bird...but my eyes opened wide to see this:

 

An Ocean Sunfish (Mola mola)!  The vultures were eating this Ocean Sunfish in a grassland at least 120 feet from the bluff edge!

So one of the first questions is, how did the sunfish get there?  It's seems unlikely that a vulture could lift such a large prey item.  It's more likely that the sunfish washed up on the beach, and then a mammal (e.g., Coyote?) carried it into the grassland.

As I was photographing the sunfish, I noticed some movement along one edge.  Looking more closely, I realized an insect with strong black and yellow markings was landing on a torn area of the sunfish:

 

I don't have a lot of experience identifying insects in this group, but I think this might be a Western Yellowjacket (Vespula pensylvanica).  Please correct me if I'm wrong.

The yellowjacket was actively carving out a piece of the sunfish!  Here's a sequence of images documenting the event, until just before the yellowjacket flew off with its prize:

 

 

 

This is a very nice example of a spatial subsidy — "movements of nutrients, detritus, prey, and consumers among habitats" — as defined by Gary Polis and colleagues in 1997. (See Polis, G.A., W.B. Anderson, and R.D. Holt.  1997.  Towards an integration of landscape and food web ecology: The dynamics of spatially subsidized food webs.  Annu. Rev. Ecol. Syst.  28: 289-316.)

Inspired by the work of Gary Polis, ecologists have been increasingly interested in the movement of resources and energy between distinct ecosystems — such as from the sea to the land.  In this case, the Ocean Sunfish, normally found in the open ocean, was washed up onto a sandy beach, and then probably carried by a terrestrial mammal to a coastal grassland where it then served as food for land birds (vultures) and terrestrial insects (yellowjackets).  I couldn't help wonder — how often do yellowjackets eat Ocean Sunfish in grasslands?

Catching some rays

 

Turkey Vulture (Cathartes aura) in spread-wing posture on Salmon Creek Beach. 

A couple of weeks ago I noticed a few Turkey Vultures in this position on the upper beach.  Do you have a guess about the wingspan of a Turkey Vulture?  (Answer is below the next image.)

 

Turkey Vultures have a wingspan of ~1.75 meters across (~70 inches or 5.8 feet).

They use this position to warm up in the morning, or to dry their wings.  If you look closely you can also see that their tails are spread broadly, too.

 

With nice shadows, this next picture illustrates the sun's position behind the vultures.  I can almost feel the warmth of the sun on their feathers!

 

Beach scavengers

It's common to see Turkey Vultures and Common Ravens cruising Salmon Creek Beach, searching for potential food items.  

On 24 January, this vulture discovered a loon that had just washed ashore.  It appeared to be trying to pull it above the swash zone.  Vultures are scavengers, feeding on carrion.  Their genus name, Cathartes, means "purifier".

This raven may have been feeding before I encountered it.  It jumped up onto the driftwood, walked along, and then swiped its bill from side to side on the end of the log (perhaps to clean it).

 

It's always interesting to see what the waves wash in, and intriguing to note what attracts the gastronomic attention of these beach scavengers.