Monthly Archives: January 2013

Doing The Wave

21 January 2013

If you love huge bird events you’re going to love what Sharon Leadbitter saw last Saturday evening.

Sharon went to the Strip District and filmed the crows coming into the roost.

Thousands upon thousands gathered in the trees on the hill from Bigelow Blvd down to the Busway.  As night approached they began to do The Wave, just like a crowd in a football stadium.

And they cheered as they rose from their seats.  (Turn up your speakers!)

Check out time code 0:59 to 1:15.

Wow!

(video by Sharon Leadbitter)

p.s. Sharon adds, “If anyone wants to join me sometime, the crows start showing up at about 4:55pm and keep coming until around 6:30 or so.” 

Wind Effect

As I write this morning before dawn, the wind is whipping around the house as a winter storm approaches from the west.

If I was at the roof peak I’d be blown away.  The wind is even faster up there (see red lines at top) where it converges to clear the house.

Outside my window on the downwind side, the air is swirling in updrafts like the turquoise lines at left.

I suppose I could find a few calm spots within the swirls if I went outdoors to experiment, but it’s not worth it.  At particularly gusty moments I hear garbage cans rattle down the alley in the dark.

 

(diagram by Barani on Wikimedia Commons.  Click the image to see the original)

Family Resemblance

.

Doesn’t this bird look a lot like a red-bellied woodpecker?

This is a red-crowned woodpecker (Melanerpes rubricapillus), photographed by Charlie Hickey in Costa Rica.

There are nine Melanerpes woodpeckers that look very similar.  Most of them live in the tropics; some are island species.  I’ve noted below where you can see three species in the U.S.

Biologically speaking, this is more than a “family” resemblance  It’s at the genus level.

(photo by Charlie Hickey)

Why We Fly in V Formation

Tundra swans (photo by Chuck Tague)

Why do swans, geese, and ducks fly in V formation?

Because it makes their journey easier.

Everything that flies experiences air turbulence that slows it down (drag).  Some of the turbulence is created by the act of flying.  For instance while rising up (lift) cones of swirling air called vortices roll off the wingtips and induce drag. Here’s a dramatic photo of a wingtip vortex, enhanced by red smoke.

Wake vortex study Wallops Island (photo from NASA via Wikimedia Commons)

The right and left wing vortices swirl in opposite directions — the left spins clockwise, the right counter-clockwise — resulting in two trailing swirls behind the airplane or bird.  Watch it happen in this video as the airplane passes through a cloud.

The induced drag is especially hard on large or heavy birds (swans and geese) and birds with small wings relative to their size (ducks) so these birds line up in Vs to reduce the turbulence.

Here’s how the line works.

In the photo below, four tundra swans are flying in the direction of the blue arrow.  Behind the leader, the blue lines show that each following bird has its right wingtip in line with the left wingtip of the bird ahead of it.

Now I’ll draw the vortices and their spinning directions using blue for the left wing, red for the right wing.  Blue/left spins clockwise.  Red/right spins counter-clockwise.

When the blue vortex meets the red vortex at the wingtip, they cancel each other out.   By lining up in this fashion, each bird has one wing that experiences less turbulence.  That makes it easier to fly.

The lead bird is out there alone, though.  He’s the only one who gets no assistance so he tires before the rest of the flock.  The flock solves this by changing leaders when the first one needs to rest.  The lead bird drops back into the V and another bird takes his place.

Long, long ago birds solved the problem of wingtip turbulence.  When we invented airplanes we found out what it was all about.

(Credits: Tundra swans in blue sky by Chuck Tague.  Line of swans by Marcy Cunkelman.  Red vortex photo by NASA via Wikimedia Commons; click on the image to see the original. Video by whosyourcaddy on YouTube. Today’s Tenth Page is inspired by a diagram on page 123 of Ornithology by Frank B. Gill.)

It’s Hot Out Here!

On this cold, icy morning it’s hard to remember last summer’s heat, but after I published Jim Logan’s peregrine photos last week I learned about this hot young bird in Downtown Pittsburgh.

Just after 2:00pm on July 6, 2012, Rachel Papa looked out her 24th floor window in the Grant Building and saw a large raptor standing on the patio planter with its mouth open.

It was an unbanded immature peregrine falcon and he was panting.

The patio was in shade but it was not comfortable out there.  It was 97oF, 13o above normal on a hot day in the hottest year on record.

The peregrine merely gazed at Rachel as she took his picture through the window.

Here, the bird is alert and curious.

 

And here he seems to be saying, “I’m telling you, it’s hot out here!”

 

These photos show that the peregrines’ impromptu Third Avenue nest produced young last year, but our watchers saw only one fledgling not four or five as is usual at the Gulf Tower nest.

If Dori and Louie do the math and feel that the Gulf Tower is safe, they’ll go home to Gulf this spring.

We certainly hope so.  As @PittPeregrines says on Twitter, “Talons crossed!”

 

(photos by Rachel Papa)

Look Closely

If you merely glanced at this feeder from afar, you might assume all the birds are goldfinches.

They’re all the same size, but the two birds at the top are common redpolls, the latest arrivals in a massive irruption of winter birds.

In western Pennsylvania they’ve joined purple finches, red and white-winged crossbills, pine siskins, evening grosbeaks, and red-breasted nuthatches, all of whom came south because of the drought up north.

I’ve chronicled other irruptions (see list below) but I don’t remember a year in which so many species visited at the same time.  This year the only thing we seem to be missing are snowy owls.

Look closely at your feeders.  You might have some exciting visitors.

(photo by Marcy Cunkelman)

Fish Fight

I love this photo that Steve Gosser posted on Facebook last week.

Textbooks describe ring-billed gulls as opportunistic feeders, “exploiting chances offered by immediate circumstances without reference to moral principle.”*

No respecters of age or experience, the top gull is a “teenager” (a second winter immature), the bottom one an adult.

There are loads of fish in Lake Erie but one of them decided to steal a fish from his neighbor rather than catching one on his own.

Fish fight!

(photo by Steve Gosser)

 

(*) per Google’s dictionary