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Friday, October 30, 2015

Thursday, October 29, 2015

Tracking

The White-tailed Kites I've been watching continue to fascinate me.  And I have more and more questions about them.

The kites' arrival time to their roost has been tracking sunset (and their departures have tracked sunrise) which isn't surprising, but it has made me wonder.  How do they decide when it's time to leave their hunting grounds?  And it's been interesting to see that the weather affects their departure time from the roost.  The kites "sleep in" on foggy days, and sometimes even "go back to bed" after a brief flight.  Are they cold?  Are they waiting for better visibility?  Are they waiting for a light cue?



 
When seen from certain angles, the dark markings around their eyes make their eyes look so large!  Does that intimidate other birds?  Or does it make them look impressive to each other?  Or, is it similar to eye-black and helps reduce glare?



Seeing lots of individuals allows you to appreciate variation.  Many of the kites seem to be molting and replacing their tail feathers.  Look for some shorter tail feathers (image above), compared to full-length tail feathers (image below).  Is it typical for kites to molt in October?  The Birds of North America account shows a question mark for molting in October, but mentions that it's possible the molt extends later into the year.



Below, a kite looks back at an approaching crow:


I'm still fascinated by this crow-chasing-kite behavior.  The kites make evasive maneuvers and sometimes screech at the crows.  (Some of the crows chase kites, others seem to fly right by.)  Occasionally the crows "buzz" a perched kite, but most of the time the crows abandon the chase once the kites have perched.  Sometimes it seems like the crows remember where the kite roost is and that they fly by, waiting for a chance for a chase.  The crows also dive at other crows.  Could the kite-chasing behavior be a form of "practice" for the crows in preparation for interactions with their own kind?

Wednesday, October 28, 2015

Flashy



Hopkins' Rose nudibranch (Okenia rosacea) on 28 October 2015

I first saw this species in the Bodega Bay area last January (see post from 3 January 2015).  I'm not sure exactly how many are around now, but it was nice to see one tonight.


Then Eric was watching the sunset and predicted a green flash.  Sure enough, the sun sank quickly below the waves at ~6:15 p.m. and a small green flash appeared at the horizon.  Can you find it in the picture below?


 The green flash is barely visible above the waves in the center.

 'Tis the start of the season to watch for green flashes on clear nights!

Sunday, October 25, 2015

Fir and feathers


I've missed these guys.  Since we moved to Cotati, I haven't seen too many Brown Creepers (Certhia americana).  I was glad to find two of them working their way up the trunks of a couple of fir trees in the neighborhood on 24 October 2015.

Saturday, October 24, 2015

Birds as leaves

How many birds do you see at first glance?

Then, how many birds do you count?


I just scanned quickly, but I counted 55 twice.  

Pine Siskins (Spinus pinus) in Cotati on 24 October 2015.
 

Thursday, October 22, 2015

A shared interest

I had a funny experience a few days ago.  I walked outside of the house and heard a very loud, "Crrraack!"  I looked around, and noticed a large nut in the street.  And then I looked around some more, and noticed an American Crow flying down to the nut.

It made me smile for a few reasons.  I'm fascinated by corvid behavior, and this was the first time I'd seen a crow doing this using height, gravity, and a hard surface to open a nut.

It also helped me solve a mystery.  A few days before this, we had found a large walnut in the front yard (on a patch of cement).  There aren't any walnut trees growing adjacent to our house, so we wondered where the nut had come from.  When I saw the crow dropping the walnut on the street, I realized what had probably happened. 


And, seeing a crow with a walnut (and then finding many walnut shells in the area) also provided some circumstantial evidence for another puzzle.  You might recall that I've been watching some White-tailed Kites come to an evening roost, and that in the 1960s a large kite roost was reported in Cotati (see post from 5 October 2015).  Those kites were roosting in a walnut orchard, so I had been wondering about whether there used to be a walnut orchard near this house. 

Of course, I'm left with another piece of the puzzle exactly where are the crows getting the walnuts, and how far is that site from our house?  We'll have to start scanning for walnut trees in the neighborhood.

Perhaps both the crows and the kites have an interest in walnuts, but for different reasons?


Wednesday, October 21, 2015

Moving tail is right!

I couldn't resist taking a few hours off from work this afternoon for a trip to Rodeo Lagoon (Marin County) to see the White Wagtail (Motacilla alba) first spotted there yesterday.  There are only about 30 records of this species in California  these long-distance vagrants might originate from Eurasia or Alaska.

Although it was easy to observe this bird with a spotting scope, my camera lens wasn't nearly strong enough for close-up photos.

Here are a couple for the record a side profile (with a hint of the black breast patch), and another photo highlighting the long tail and feeding position:



Len posted some much better pictures here.

And if you're interested, the White Wagtail account (along with the figures and table) from the Rare Birds of California is informative.

P.S.  The genus, Motacilla, means "moving tail" and in this case, the name is quite appropriate.  Check out this video posted by Stephen Berylant.

Tuesday, October 20, 2015

Tight formation


Brown Pelicans (Pelecanus occidentalis) along the Sonoma Coast, 18 October 2015

Monday, October 19, 2015

Seeing red

Well, I've run out of time again, but I promised to post an answer to last night's mystery photo, and I can share a few more images of the same animal.

Here's the picture from last night (below).  Did you have a guess about what type of animal this is from?


These are the claws of a Pelagic Red Crab (Pleuroncodes planipes)!

I've been following with great interest reports of Pelagic Red Crabs (sometimes called "tuna crabs") washing up in Southern California, and more recently in Central California (during the second week of October in Monterey and Pacific Grove).  Only rarely has this species made it to Northern California, but it seemed like the chances were pretty good this year, given the significant El Niño conditions.

So Eric and I walked Salmon Creek Beach on 17 October 2015 with Pelagic Red Crabs on our minds.  We were nearing the end of the walk without seeing any signs of one, and then we had a funny moment.  At the same time, in separate locations (~4 feet apart), Eric and I both looked down and said something like, "What's this?!"  Each of us had spotted a telltale red claw.

We think this crab had just been eaten by a gull, but there were two claws and one leg on the beach.

Amazing!  We can only find a few records for Pelagic Red Crabs in Northern California Duxbury Reef and Fort Bragg in 1985, Cordell Bank in 2015 (by Point Blue), and now this one in Bodega Bay. [Thanks to Jim for helping us track down these records.]

This is very much a southern species, most abundant off the west coast of southern Baja California.  

Here are a few close-ups of one claw under the microscope.

Long pincers:



Dramatic "bristles" (called setae) bundles attached to raised tubercles:



The photo above was taken out of water.  The next image shows the "bristles" under water, fanning out like paintbrushes.


We read one description that said Pelagic Red Crab "bristles" increase surface area and function like a "parachute" when the crabs are drifting in the water column.

I hope to see an entire individual some day.  Keep your eyes open when walking local beaches, or when you're out on the water If you find one, I'd love to hear about it!

 

Sunday, October 18, 2015

Mystery invertebrate

Well, I've run out of time tonight.  But since I mentioned I would be sharing an interesting invertebrate sighting, I'll post one picture and perhaps you'll have some guesses about what it is!


More about this tomorrow night!

Saturday, October 17, 2015

Calling, hunting, and begging

A few pictures from 17 October 2015:

I was watching shorebirds on the inside of Doran Beach, enjoying the calls of Long-billed Dowitchers (Limnodromus scolopaceus) included in the photo above when this happened:


 
Peregrine Falcon (Falco peregrinus) hunting shorebirds over Bodega Harbor



Later we watched this juvenile Elegant Tern (Thalasseus elegans) begging from an adult on Salmon Creek Beach (Check out the 'do!)


P.S.  We also have an exciting invertebrate find to share with you, so stay tuned!

Thursday, October 15, 2015

Like clockwork

Every year, at this time of year, I have a work task to accomplish in the Bodega Dunes.  I walk through the same areas each time, and almost every year I see one of these:


I had heard that a few Burrowing Owls (Athene cunicularia) had been seen on Bodega Head already this year, so I had my camera ready just in case...and then got lucky.

I also heard that a Burrowing Owl was observed along the Pomo Canyon Trail (near Shell Beach), so keep your eyes open for these charismatic grassland birds.

P.S.  For previous Burrowing Owls posts see 2 March 2015, 6 February 2013, and 19 March 2012.
 

Wednesday, October 14, 2015

"Planetary dance"

A couple of days ago, Skip commented that Mars was probably in the picture I posted of Jupiter, Venus, and the Moon.  He was right, so I thought I'd try again and this time, to take a picture highlighting Mars.

Here's the first attempt (taken on 14 October 2015). Venus is at the top (the brightest), Jupiter is at the bottom (second brightest), and Mars is just above Jupiter.  It's small and reddish in color, so harder to see.  Can you find it?



Here's the same picture with an arrow pointing to Mars:



And so you can see it better (and find it yourself in the morning sky), here's a close-up of Jupiter (bottom) and Mars (top).  [Mars is very easy to see with binoculars and is distinctly red.]


Skip also mentioned two special celestial events coming up soon:

- Jupiter and Mars will be in conjunction (at the same latitude when viewed from Earth) on October 17th the closest they'll be to each other until January 2018.  

- And then Jupiter will continue moving towards Venus, and will be in conjunction with Venus on October 26th.  

Watch for this "planetary dance" in the eastern sky just before sunrise.
  

Tuesday, October 13, 2015

"Sharktober"

I've heard of a few Great White Shark (Carcharodon carcharias) attacks on marine mammals during the last few weeks — off Half Moon Bay, between Bodega Head and Bodega Rock, from the Farallon Islands, and next to the Alcatraz Island pier.

Yesterday I encountered the probable remains of a white shark attack washed up on a local beach.  It was half of a sea lion.  For those interested, I'll show a picture below.  (If you'd rather not see a half-eaten sea lion, then read no further.)

First I'll show the tooth of a Great White Shark that I found in 2005.  I posted this image in 2012.  I'll admit, when I found this tooth 10 years ago, I had no idea exactly how rare it was to find a white shark tooth.  I was new to California, but knew white sharks occurred in this area, so I naively thought, "Nice!  A shark tooth!"  And now I'd say, "WOW!  A SHARK TOOTH!"  I'll show the sea lion picture after the tooth.




Okay, here's the sea lion likely cut in half by a shark:


When I first noticed this animal from a distance, I was viewing it head-on and observed the silvery color.  I thought it might have been a harbor seal.  As I approached it, I noticed the long flipper and realized it was a sea lion.  I hadn't known sea lions could look so silvery (I generally think of them as quite brown), but I read that the fur of younger animals can be this color after a molt.

Relatively recent research on white shark movements in this area has revealed that sharks spend time near the Central California coast in late summer/fall (primarily September-November), then migrate 2000-5000 km offshore (primarily from April-July).

If you'd like to learn more about these impressive migrations, you can read more here:


Monday, October 12, 2015

From islands off Baja


This is one of those times when I don't have great pictures, but I'm going to show a few images because they represent an important record.

At the end of the day today there were thousands of Black-vented Shearwaters (Puffinus opisthomelas) flying north past Bodega Head.

These are small shearwaters, and they were about 1/4 mile offshore, but you can still see their distinctive profiles with stiff wings.  And in these images, on some individuals, you can just make out the coloration dark upperparts and light underparts.




At ~5 p.m., through a spotting scope, I counted ~135 Black-vented Shearwaters/minute (on average).
 

Black-vented Shearwaters are generally a southern species breeding on islands off the west coast of Baja California, and dispersing north to Point Conception.  In some years, they make it to Monterey Bay.  When the water is warm, they make it to Sonoma County.  (Rarely they make it as far north as British Columbia.)  Their abundance off Bodega Head in 2015 is probably related to El Niño and warmer water conditions.  Water temperatures reached over 16°C (61°F) today (about 3°C above average for this time of year).

Because they're rare off Bodega Head, I don't have great pictures of this species, but here's a photograph from Monterey Bay on 22 August 2014 (with a couple of cormorants and a larger and darker Sooty Shearwater for comparison):


Black-vented Shearwaters can be seen close to shore, so watch for them if you're at the coast this fall.

Sunday, October 11, 2015

Caching in

I mentioned Clark's Nutcracker (Nucifraga columbiana) a few days ago, but didn't show any pictures.  Here are a few images taken near Monitor Pass (along Route 89).



These interesting corvids (related to crows and jays) are pine specialists pine nuts are their preferred food.



This nutcracker was eventually successful:


Clark's Nutcracker's cache pine nuts for a year-round source of food.  Because of this, they affect the dispersal and distribution of pines, e.g., sometimes the pines grow in clusters as a result of a number of seeds (typically 1-30) stored at each cache site (most often underground).

When I read this, I wondered how many cached seeds are relocated and eaten and how many germinate and become new trees?  I suppose the nutcrackers "win" either way, although getting a new crop of seeds via the second route will take a lot longer!

P.S.  Facts above from the Birds of North America account (Tomback 1998).

Friday, October 9, 2015

Celestial trio


Jupiter, the Moon, and Venus (from left to right), photographed in the eastern sky at ~6:50 a.m. PDT.




A close-up of Jupiter and the Moon

Thursday, October 8, 2015

Down jacket


Bushtit (Psaltriparus minimus), in the early morning near Mammoth Lakes, CA, on 8 October 2015

:)

Wednesday, October 7, 2015

At the base of the mountains

We were in meetings for most of the day, but I snuck in a few pictures.  Here are three of my favorites from today:

Mountain Chickadee (Poecile gambeli)


Least Chipmunk (Tamias minimus)


Shadow of a Red Admiral butterfly (Vanessa atalanta) on an aspen trunk (with sapsucker holes)

East of the Sierras

I'm at a meeting near Mammoth Lakes, CA, for a couple of days.  Here are a few pictures from the drive yesterday (taken from Route 89 and Route 395):

I stopped briefly to stretch at ~8,000 ft. along Route 89.  When I stepped out of the car, I heard Townsend's Solitaire's (Myadestes townsendi) singing!  (See one perched above.)  The next bird I heard was a Clark's Nutcracker (Nucifraga columbiana), and then a Mountain Chickadee (Poecile gambeli).  A nice trio!


Cloud shadows
 

This damselfly flew in and landed in the parking lot at a rest stop in Antelope Valley (Mono County).  It's either a Great Spreadwing (Archilestes grandis) or a California Spreadwing (Archilestes californicus).  It flew off, and I couldn't find it again, so I'll need to check in with some experts to see if they can identify it from this photo.


 Mountain snow 


 
Mono Lake

Monday, October 5, 2015

Questions

Okay, I'll admit it.  I have a new addiction I'm fascinated by kite roosting behavior.

After my first post about this on 17 September 2015, I've continued to watch these White-tailed Kites come into roost in the evenings and leave the roost in the mornings.

I have lots of questions about this phenomenon.

Although the light levels are dim, when I've been able to see the birds well enough, it appears that many of the birds have orange markings on their breasts, indicating that they're juveniles.  Is the roost site made up primarily of juveniles, or is it shared among different-aged birds?



It appears that some of the kites perch in the tallest trees near the vicinity of the roost before actually entering the roost (see example below).  Does the availability of high perches nearby play a role in the choice of a roost site?  How many kites do you count in the next photo?  [Click on the photo for a larger version.]


There are at least five, and probably six, White-tailed Kites in the photo above.  Two are obvious in the upper left; there's one in flight; one perched below the bird in flight; and there's one perched on the far right.  I think there's also a hidden bird behind the foliage just to the right of the two birds perched up high.


The crows won't let these kites go by without many minutes of harassment (both entering and leaving the roost).  Sometimes there are eight or more crows chasing one kite!  (However, I've also noticed that some crows don't bother with the kites and fly directly to their own separate roost site.)  It seems like being harassed every night and every morning could get tiring, but perhaps the kites are used to it?  Why are the crows so concerned with the kites?  Or is it more of a "game" to them?


It's hard to count the kites, as many of them come to the roost in a very short time period.  I've seen them choosing a few different roost trees.  Do the same individuals roost in the same trees?  Or do they switch, and use different roost sites on different nights?  Tonight many of them chose a roost site that I hadn't seen them use in weeks, and they all seemed to fly directly to it.  How did they all know to use that particular roost site tonight? 

How will the number of kites change through the fall/winter?  Does weather affect the choice of roost site?  Does the type of tree matter?  Do the surroundings matter?  How far are they coming from?  Does a daylight cue trigger their arrival/departure to the roost? 


I have so many questions about this that I started doing some research.  Interestingly, one of the first articles I came across was an article by Gordon Bolander and John Arnold describing a White-tailed Kite roost in 1964 in Cotati! 

They observed kites coming to roost on several different dates, e.g., Oct. 24 = 75 birds, Oct. 25 = 156 birds (!), Oct. 28 = 85 birds.  Gordon Bolander and Mike Parmeter found the birds using a "walnut orchard" as a roost site.  I don't know if there's still a walnut orchard here, or if the walnut orchard used to be close to where the kites are roosting now?  Could this roost site be a traditional site, passed on through many generations?  I'll have to ask Mike where that walnut orchard was.


P.S.  The article cited above is: Bolander, G.L. and J.R. Arnold.   1965.  An abundance of White-tailed Kites in Sonoma County, California.  Condor 67: 446.