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Wednesday, July 31, 2013

Pollen-covered chaps

A few days ago I encountered these wonderful bees on Bodega Head.  At first I was simply impressed with the extremely dense, long brown hairs on the legs — they somehow reminded me of chaps.


And then one flew in covered with bright yellow pollen.  


Just after it landed, I was trying to photograph this striking individual when it started to dig into the ground.  What happened next was a little surprising.  The bee disappeared below the surface within about 30 seconds!  Here's a sequence:


I looked around for another bee to see if the same thing would happen.  Sure enough, here's another sequence of a different individual (next image).  Once the bee was below the surface, you'd never know it was there.  The only telltale mark was the loose soil (similar to an anthill) in the general area.


I'm afraid I don't know what type of bee this is yet.  Nor do I know exactly what's going on here.  I'm wondering if this could be a species of Andrena?  Perhaps the bees with pollen are females digging to access burrows where they will deposit and provision eggs?  How long will they stay underground?  What type of burrow or tunnel system is down there?

I'll have to do more research and report back later.  In the meantime, enjoy the mystery of the burrowing bees with the pollen-covered chaps!


Tuesday, July 30, 2013

Bright and early

Sometimes your day needs a little brightening...


...and a Hermit Warbler is just the thing!


I looked up from my desk at the end of the day to see this warbler moving around from branch to branch in the shrub outside my office.


It was actively searching for food, so difficult to photograph, but I eventually ended up with a few images for the record.


Hermit Warblers don't nest on Bodega Head.  They're generally more associated with coniferous forests to our north in Washington, Oregon, and northern California (although they're rare nesters in both Sonoma and Marin counties).  They'll winter primarily from Mexico to Nicaragua, with some individuals remaining along the California and Oregon coasts.


This individual is likely an early migrant.  I don't know if it's up-to-date, but the Birds of North America account lists the fall migration dates for Hermit Warbler at the Farallon Islands as 31 July to 20 November, with a peak from early August to early September.  Today's date of 30 July is definitely on the early side!

Monday, July 29, 2013

Thanks


The white and green flowers of the Coast Piperia (Piperia elegans), one of two orchids found on Bodega Head, photographed on 28 July 2013.

These pictures are thanks to Peter, from whom I first learned that orchids grew here...and David and Mike, who have continued to remind me that this species was just about ready to bloom.  Thank you!

Here's a view of the entire inflorescence, magically emerging from the earth.  


Sunday, July 28, 2013

Different points of view

Yesterday I spent a little time watching a nice mixed flock of shorebirds on the outer coast of Bodega Head. 

The photo below is mostly Surfbirds, but there are a couple of Black Turnstones.  Can you find them?  The turnstones are slightly smaller and have extra white stripes where the wing meets the body and up the center of the back. 


[One Black Turnstone is by itself following a tight cluster of Surfbirds near the center of the flock; the other is in the very lower right corner.]


Surfbirds coming in to land:



I'm calling the next one, "A Peregrine's Point of View."  I don't know if this is what a falcon sees when pursuing a shorebird flock, but it's interesting to wonder about!



Mostly Surfbirds (all but one) on the shore:



And one close-up (below).  Since they have just returned from Alaska, most of the Surfbirds are still in breeding plumage (paler faces), but note the bird on the lower right (darker face) that has molted into non-breeding plumage already.


I hope you don't mind more pictures of Surfbirds...I just can't seem to resist them!  I'm so glad they've returned from their journey north!

Saturday, July 27, 2013

Breaking the surface

I haven't posted about a mammal in a while, so this afternoon I decided to try to photograph the Humpback Whales that have been visible off Bodega Head during the past week.  

I finally spotted a couple of whales, but they were pretty far offshore, so I wasn't having much luck with a good photo.  Here's the best shot which isn't saying much, but at least it alerts you to watch for Humpbacks if you're at the coast anytime soon.  Look for the very short dorsal fin.


More surprising was that while I was trying to photograph the Humpbacks, another cetacean surfaced much closer to shore.  My view of it was brief, but I saw a fairly long, dark back and a very hooked dorsal fin (see next photo).


I waited and waited...and waited and waited.  And just when I thought this whale wasn't going to appear again, it surfaced, this time further offshore.  I barely captured it on film before it disappeared:


I'm pretty sure this was a Northern Minke Whale (Balaenoptera acutorostrata).  It was too large for a dolphin, i.e., too much back was visible before the dorsal fin appeared.  It was all by itself.  It swam very quickly and surfaced only twice before diving again and staying under for over 5 minutes.  Note that the dorsal fin was relatively tall and falcate (sickle-shaped).

It's not common to see Minke Whales from shore, or even from boats in this area (in my limited experience).  So when the viewing conditions are right, as they have been recently, with calm seas, light winds, and overcast conditions, keep your eyes open for whales breaking the surface!

Thursday, July 25, 2013

Ready to go

My favorite picture from today:


Believe it or not, this hydromedusa originated from a hydroid colony that looked like this:


When you zoom in, there are tiny medusae (like the one in the first photo) attached to the polyps within this colony.  In the following image, there are several medusae in various stages of development (some younger, some older).  Can you tell which ones are just about ready to swim away from the polyp?


On the lower side of the polyp, there are two younger medusae — they look like little ovals with golden spots at the base.  On the upper side, there are two older medusae, one in the foreground and another in the background their tentacles are now unfurled.  Both of these older individuals appear poised to take off into the wide, wide ocean very soon.

P.S.  To give you some sense of scale, the entire colony in the second photo was only ~2 cm tall.  The hydromedusa is only ~1 mm long.  All of these pictures are greatly magnified.

Wednesday, July 24, 2013

White-crusted

Not much time tonight, but here are a few shots of a nice little nudibranch from the rocky intertidal zone this morning on Bodega Head.


This is a White-crusted Cuthona (Cuthona albocrusta) among some hydroids.  These nudibranchs are small — this one was probably just under 1 cm long.  [And yes, that's another even smaller nudibranch above the Cuthona.  It was so tiny that I didn't even see it when I took this photograph.  I think it's a species of Doto.]  Here's another view:


I wasn't sure if my field photographs would come out, and since I hadn't documented this species for Bodega Head yet, I brought it in for a few microscope images.  




You can see why it's called "white-crusted," although I think "frosted" would be another good description.

Tuesday, July 23, 2013

Little narwhals

Remember the Giant Green Anemones (Anthopleura xanthogrammica) spawning in late June?  (You can review that post here.)  Well, there's more to the story.

I mentioned that you don't see anemones spawning in the field very often.  Eric's in the middle of teaching a summer class about marine invertebrates.  So when I noticed the anemones releasing eggs and sperm, I ran up to the lab and called him to see if he wanted to take advantage of the rare opportunity.

He appeared at the site a few minutes later with a flask and pipette.  He obtained a few eggs from a female anemone (look for all of the orange dots in the flask in the picture below).

 
Then he sucked up a tiny bit of sperm from a male anemone and released it into the flask (also note the nice upside-down reflection of the Bodega Head cliffs and waves at the bottom of the flask) :


A couple of days later there were healthy, swimming, Giant Green Anemone larvae!  This is what they looked like when 5 days old:


This is called a planula larva.  You can see that the edges of the larva are covered with short hair-like structures (cilia).  These are used to propel the larva through the water they are very fast swimmers! 

Note the very long apical tuft.  This long, pointed structure is sometimes twisted (it's made of several strands held close together)...and the planula larva swims with the tuft pointed forward.  Perhaps it's my wild imagination (is that possible?), but they remind me of little narwhals as they swim along!


Arthur Siebert did a study on these larvae in 1974 at the Friday Harbor Laboratories.  He tried to get the larvae to settle on various substrates (and metamorphose into little anemones), but they never did.  And as far as we can tell, no one has ever been able to get them to settle in the lab, so no one knows how long they stay in this larval stage before becoming the anemones we know so well.


I hadn't seen Giant Green Anemone larvae before, so it was quite an experience to see how different they look in the larval stage.  Who knew that Giant Green Anemones look like little narwhals when they're young?


Monday, July 22, 2013

1939

After seeing last night's post, Janet wrote to ask about the history of Bodega Harbor and the jetties at the harbor entrance.  There are many stories to tell there (too many for one night!), but her questions spurred me to include this picture of the entrance to Bodega Harbor in 1939.


Many people haven't seen what the entrance to Bodega Harbor looked like before the North and South jetties were built in 1942.  Note that the tip of Doran Beach was recurved inward towards the inner portion of the harbor (on the inside of Campbell Cove) — creating a very narrow entrance to Bodega Harbor (sometimes referred to as Bodega Lagoon at that time).  It now curves outward, but the current shape is artificial and is dependent on the jetties and bulkhead (on the inside of the spit).

This U.S. Army Corps image also shows the natural shoreline before Westshore Road was constructed and before PG&E began development of the site for a nuclear power plant (never completed) at Campbell Cove.  

It also illustrates Gaffney Point (the sandy point at the top of the image) in a nascent stage without much vegetation (dune or salt marsh)...and the Gaffney Ranch site just to the right of Gaffney Point.

Thanks, Janet, for inspiring me to share this historical image!

Sunday, July 21, 2013

Aerial view


I didn't get a chance to go for a walk today, so I decided that it would be fun to reach back into the archives and show an aerial view of Bodega Head.  This is a photo I took from a small plane on 31 January 2009.

Saturday, July 20, 2013

Southbound again?

This hummingbird landed in a shrub outside of my office window on 19 July 2013.  I didn't have my camera at the time, but luckily the bird was still there after I retrieved it from my car.


The hummingbird spent a few minutes preening, so I took several pictures from different angles.  Here's one showing a bit more of the throat:


And one with the tail spread, a valuable view for this species:

 
Unfortunately, having moved from the East Coast, I don't have a lot of experience with this group of hummingbirds.  It's either a Rufous or Allen's Hummingbird.  The Birds of North America account gives some indication of how difficult it can be to tell them apart: "Female and immature Allen's are, in most circumstances, impossible to distinguish in the field from female and immature Rufous Hummingbirds." 

So perhaps I'm crazy to try!  Feel free to chime in if you have thoughts about the identity of this bird.  No matter what species it is, it still leads to useful hints about things to look for in the field, and some interesting insight into hummingbird behavior/migration.

I'm guessing that this is an adult female (correct me if you think otherwise!).  There's a relatively distinct throat patch, and the central tail feathers appear to be mostly green (see below).


One of the most useful characters for separating Rufous and Allen's hummingbirds is the width of the outermost tail feather.  In this case, I felt that that outermost tail feather was relatively broad, so I started leaning towards this being a Rufous Hummingbird (Selasphorus rufus).  Here's the tail feather photo again:


Rufous Hummingbirds generally nest further north (as far north as Alaska) although it sounds like knowledge of their breeding distribution in this part of California is somewhat uncertain due to the difficulty of separating them from Allen's Hummingbirds.  They depart their more northerly breeding grounds in mid-June and early July and southbound migrants may start to appear at latitudes similar to this in mid-late July (right now!).  They'll winter further south, in southern California and Mexico.

I was grateful for such an intriguing visitor, and I look forward to any comments you might have about its identity.

Thursday, July 18, 2013

Male and female gliders?

I know I just posted about Spot-winged Gliders, but there are several reasons to talk about these dragonflies again.  I mentioned that I had seen quite a few recently, but now I think I can say that this is the largest number I've ever seen on Bodega Head.  They seem to be everywhere right now, especially feeding on the lee side of shrubs.

On the southern end of Bodega Head this afternoon there were quite a few perching on the vegetation close to the ground.  Spot-winged Gliders are very active fliers, so whenever you can see them perched, it's a great study opportunity. 

The following picture shows a view with three perched individuals — can you find all of them? 


They're all in the center of the image, two at the top close together, and one near the bottom.  Here's a close-up of the top two individuals:




The other reason to post about Spot-winged Gliders has to do with some questions I now have about how to identify males and females.  Sometimes it's fairly easy to identify male and female dragonflies either by color (as in birds), or by looking at their reproductive parts (sometimes visible in the field, either with binoculars or after catching them and viewing them with a magnifying lens). 

In this case, it's not so easy.  Male and female Spot-winged Gliders have similar coloration, especially when they're young.  And it turns out that their reproductive parts aren't that helpful.

When you read about sexing Spot-winged Gliders in field guides, you often don't receive much guidance.  You may read that adult males have red faces, but that's only helpful if you have an adult and if you can see the face.  (Both adult females and younger males have yellow faces.)  

In Dragonflies and Damselfies of the West, Dennis Paulson mentions that females have "slightly longer and more slender cerci."  The cerci are the paired appendages pointing backwards from the last abdominal segment.  Unfortunately, I'm not sure what "slightly longer" means, and without comparing a bunch of specimens, I can't evaluate this character yet.

Walker and Corbet, in The Odonata of Canada and Alaska, say this about females: "the brown spot of the hind wing slightly smaller than that of the male."  This is interesting and worth checking out further!

When I was reviewing my pictures from this afternoon, I wondered about a character that no one has mentioned but is often a good one for female dragonflies in general: the overall shape of the abdomen.  Females often have broader, more rounded abdomens (appearing swollen), while males have narrow and often constricted abdomens.

Here are close-ups of the upper two individuals from the photo above:



Now compare the two individuals above with the next two dragonflies that I photographed nearby, and look specifically at the shape of the abdomen.



Did you think the first two were broader (more likely to be females), and the last two were narrower (more likely to be males)?  

I realize the angles are different, so this isn't a completely fair test.  But it's convinced me that the next time I see Spot-winged Gliders perched, I'll be checking the shapes of the abdomens (and the sizes of the hindwing spots) to better evaluate whether this might be a good character for separating males and females.

P.S.  I know this has been a long post.  But while reading about Spot-winged Gliders tonight,  I encountered another interesting line in Dragonflies and Damselflies of California by Tim Manolis.  He says that the veins in the hindwing spot "become lighter with age, and the spot may be obscured."  I'm a bit puzzled by this, as my impression is that these are younger dragonflies in these photos (with strong abdominal markings), but they show pale veins within the hindwing spots.  I'll have to ask Tim about this fact.

Wednesday, July 17, 2013

They're fuzzy!

Today I tried to photograph Point Reyes Salty Bird's-Beak (Chloropyron maritimum ssp. palustre) in the salt marsh.  [That has to be one of the longest common names for a plant on Bodega Head.  Can you think of a longer one?]  

I didn't end up with great pictures, so I'll have to try again.  But I did learn a couple of interesting things about this wildflower when reviewing the pictures.

Here's one image that shows a cluster of flowers.  Can you see the small hole at the top of the flower in the center of the picture?


The next photo shows another view, this time looking down at the flowers from above.  You can still see that tiny hole (lower left flower). 


I'm wondering if the hole was made by an insect boring into the flower?

And although I've always liked Point Reyes Salty Bird's-beak, and I make a point to look for it flowering every year, I hadn't realized the flowers were quite so fuzzy!  (The botanical term is puberulent.) 

Here's a close-up of the dense hairs on an individual flower:


If you encounter this species, tread carefully, as this native annual is relatively rare.

Tuesday, July 16, 2013

Pink and orange

Okay, I'll admit it.  When birding on Cape Cod, I would be happy just to see a Marbled Godwit, nevermind try to figure out its age or sex.  But Marbled Godwits are much more common in Bodega Harbor and when you see lots of individuals throughout the year, it's easy to start asking questions about their various plumages and appearances.

I was reviewing some pictures from 7 July 2013 and noticed that some of the Marbled Godwit bills were pink at the base, while others were orange (see image below).  [There are also Willets (with shorter, gray bills) in these images, but ignore them for now.]

  
After a brief perusal, I can't seem to find much information about bill color in Marbled Godwits.  The Birds of North America account states that males have a brighter orange base of the bill during the breeding season.  Are the individuals with orange bills males and those with pink bills females?  Can anyone provide some insight?

If it's true that you can use bill color to separate males and females at this time of year, you can try your hand at it with the next picture.  For the godwits with visible bills, how many females (pink bill bases) and males (orange bill bases) do you see?  [You can click on the image to see a larger version.]


I would say 4 females and 4 males, i.e., 4 with pink bill bases and 4 with orange bill bases.  In the upper right corner, there are 3 with pink bills and 1 with an orange bill.  In the lower left corner, there is 1 with a pink bill and 3 with orange bills.  

I'm not sure you can use bill color to separate males and females, but it's an interesting question and exercise!  And if bill color isn't an indicator of sex, why does it vary?