Merlin, the Magician

  

Whew!  We've been attending a virtual meeting during the last few days — which means a lot of time looking at a computer screen.  So it was nice to get out for a walk around the neighborhood in the late afternoon, and even nicer to see a Merlin (Falco columbarius)!

If you're not familiar with them, Merlins are small falcons, a bit larger than American Kestrels but smaller than Peregrine Falcons.  They're generally darker than kestrels...and note the relatively dark face and the pale stripe above the eye:

 

 

 

 

 

 

The Merlin was joined in this tree by an American Crow, making it easy to compare the size difference:

 

 

 

Merlins are ~10-12" long with a wingspan of ~24-25", while American Crows are ~17.5" long with a wingspan of ~39".

Baby blue eyes

A quick shot from our backyard last night (20 May 2020):

 

This year a pair of American Crows (Corvus brachyrhynchos) nested in a tree in our backyard.  The juveniles (at least two of them) just left the nest and are starting to walk around the tree, jumping from branch to branch and taking short flights.  

I was struck by the beautiful blue color of their eyes.  Apparently the eyes will be blue for ~2 months, then turn to gray and then brown.  Note also the pink gape (at the inner corner of bill), which will be visible for ~3 months.

Perhaps because we've been home more during the shelter-in-place order, we've seen quite a few fledglings in our yard.  Along with the Oak Titmice, Bushtits and American Crows, we've also seen juvenile Bewick's Wrens recently.

Acorns for dinner

 

American Crow (Corvus brachyrhynchos) eating an acorn in our yard on 23 November 2017

"crow-motion"

 

Very large flocks of American Crows (Corvus brachyrhynchos) have been flying by our house around sunset.   

This is our second year at this house.  Last year the crows had a roost site to the south, but this year the roost is apparently to the north.  

Tonight a flock paused and circled overhead for a few minutes before continuing on.  They were very vocal, and it was hard not to look up and wonder what all of the "crow-motion" was about...

 

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?

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?

 

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.
 

Sailor's delight

Around 8 p.m., the air temperature started dropping, a breeze began to blow, and dark clouds were visible to the east.  I wondered if it was raining somewhere:

 

I went outside for a better view, and noticed large flocks of American Crows flying to roost:

 

I went out a third time to check on the sky, and this time I looked west:

 

Wow!  

It only intensified:

 

I hope some of you got to see this sunset, too.  Or perhaps the full moon a little bit later?

To the roost

Tonight I was thinking about a friend who used to sit out in his yard at the end of the day and watch the sky for activity — birds flying by, butterflies coming into roost.  I decided to give it a try.

It was a beautiful night.  The clouds were amazing and there was quite a bit of bird activity.  Not long after I sat down, I was a little shocked to see a Peregrine Falcon fly by.  This is my 9th year in this house, and that's the first Peregrine Falcon I've seen here.  Perhaps I should be sitting down to look up at the sky more often!

At about 7:20 p.m. I started to notice flocks of American Crows (Corvus brachyrhynchos). Sometimes it would just be a few birds, but other times over 20 birds flew by at once.  Here's the first group I photographed.  How many crows do you count in the image below?

 

(I counted 10 individuals.)

Flocks of crows continued to appear in pulses.  Occasionally they'd call, but mostly they'd fly by silently.  How many crows do you count in the next image?

 

(I counted 18 individuals.)

I kept watching.  And I kept counting.  At about 7:50 p.m. the background noise, i.e., all of the anthropogenic sounds, got noticeably quieter.  This made it interesting as I could then hear the wings of the crows as they approached and flew overhead.  How many crows do you see in the image below?

 

(I counted 9 individuals.)

I wrapped up around 8 p.m.  Although I didn't do a great job counting because I was also trying to take photographs, I counted at least 150 crows in about 40 minutes.  All of the crows were flying from the southeast to the northwest.  It appears that there is a communal roost somewhere in that direction!

Crow roosts may consist of hundreds to thousands (or even millions) of individuals.  The number of individuals in a roost increases after the breeding season and peaks in early to mid-winter.  Roost behavior has been studied in several locations.  In one study they found that most crows begin to arrive at the roost site about 30-40 minutes before sunset.  And in another they found that the majority of individuals have entered the roost site in the window that spans 10 minutes before and 10 minutes after sunset.

A few birds stopped briefly before continuing on.  I wonder where their roost site is?

 

I'm very thankful for a summer evening with shape-shifting clouds and surreptitious crows!