Monthly Archives: March 2011

Third Egg at Pitt

Dorothy conveniently laid her third egg this morning while everyone was watching from their computers so we received up-to-the-minute reports from her fans. 

Here she is with all three eggs. 

Watch Dorothy at the Cathedral of Learning -- and her counterpart Dori at the Gulf Tower -- on the National Aviary webcams.

When you watch Dorothy you'll notice that she incubates the eggs now.  This is likely to be her next-to-last egg, though she may surprise us.  (Actually, she seems to enjoy overturning all my predictions!)

We'll just have to wait and see.

(photo from the National Aviary webcam at the Cathedral of Learning)

Anatomy: Field of View

Several weeks ago I declared an end to my Friday bird anatomy series but I found this interesting diagram so here's an unscheduled lesson.

Field of view is the angular extent of vision at any given moment.  It's basically "all you can see without moving your eyes."

Prey species, like pigeons and robins, usually have a very wide field of view because they need to see danger coming from any direction.  To achieve this most of their vision is monocular, like our peripheral vision, with only a narrow angle of binocular vision with good depth perception.  It's so important for them to see what's coming that some prey species can move each eye independently!

As shown above a pigeon can see nearly 360 degrees around its head, a real advantage when avoiding a peregrine.

Predator species usually have a narrower field of view because they need to have good depth perception in order to capture prey.  The owl's field of view is more like ours with a wide area of binocular vision and narrow bands of peripheral, monocular vision on either side.

Peregrines and people have fields of view similar to the owl's.  Ours is actually wider than the diagram.  We can see 180 degrees.

Here's how to find your field of view, which is basically a test of your peripheral vision.  Hold up your index finger in front of your nose and close one eye.  While looking straight ahead, move that finger around your head toward the ear near your open eye.  When you can no longer see your finger, that's where your field of view ends.

Now find out where your binocular vision ends.  Open your closed eye, close your open eye (i.e. switch eyes).  Look straight ahead and move your finger in the same direction as before.  When you can no longer see your finger, that's where your binocular vision ends.

Of course, these tests only work if you have good vision in both eyes.

(illustration from Wikimedia)

First Egg at the Gulf Tower!

This morning at about 2:45am, Dori laid her first egg of the season at the Gulf Tower in Downtown Pittsburgh. 

Thanks to Michelline who captured this screen shot.  I'll post more pictures today as the light gets better.  (No color until the sun rises...)

Video!  Here's a YouTube video from Sharon Leadbitter, taken before dawn.  You'll see feathers flying from the left (Louie is plucking prey) and then Louie comes to the nest and bows to Dori to tell her breakfast is ready.

First color photo of the egg:

(photo from the National Aviary webcam at the Gulf Tower)

Keep the Rain Out of the Drain

It rained again last night. And yesterday. And last week.

This year's rainfall is already 4.38" above normal; 67% more than we usually get.  All the excess rain fell since February 1.

This has caused flooding, though nothing extraordinary for Pittsburgh in the spring, and a less publicized problem called combined sewer overflow.

Prior to the 1940's the older towns in Allegheny County built their sewage collection systems to do two things at once:  carry rainwater off the streets (storm sewers) and collect sewage (sanitary sewers).  It was cheap to build combined sewers because they only require one pipe.  There was no law against building new systems this way until the 1940's when we could no longer tolerate the problem it caused.

The problem is that when it rains too much the sewage treatment plants cannot handle the inflow of rain+sewage so the excess goes directly into the river.  As little as 1/4-inch of rain can cause a combined sewer overflow in Allegheny County.

Fixing this problem will cost billions of dollars, but fix it we must.  Allegheny County is under a consent decree that requires us to finalize a plan by 2012 and fix the problem by 2026.  (It's about time we did!   Click here for a very interesting history of river use and water treatment in the Pittsburgh area.)

Meanwhile there's something each of us in Allegheny County can do to prevent rainwater from overflowing the sewers.  Last year the county changed the plumbing laws so that we're allowed to unhook our downspouts from the sewer system and install rain barrels or rain gardens to prevent the rain from going down the drain.

You can learn how to do this at a seminar at noon next Wednesday, March 23, at Schenley Park Visitors' Center called Keep the Rain Out of the Drain.  Click here to for more information and to let them know you’d like to attend.

Every little bit helps.

(photo from Wikimedia Commons.  Click on the photo to see the original.)

Now There Are Two

Dorothy laid her second egg at 9:43pm this evening, March 15.  It was hard to get a webcam photo showing both eggs because she stayed very close over them. 

Update on Wednesday, March 16:  One of Dorothy's fans who follows the peregrines in Rochester, NY captured the moment of egg-laying on a YouTube video and posted it on the Rochester falconcam Facebook page called RFalconcam.  Both the photo above and the video are in black-and-white because they were taken at night using infrared light. 

Dorothy's eggs are actually rusty red.  Here are their true colors with E2 standing next to them.

Another update, Wednesday March 16, 1:20PM:  At lunchtime Karen Lang and I met at Schenley Plaza to watch the peregrines and saw Dorothy and E2 perched high on the Cathedral of Learning (CL) above the nest.  Then Karen heard Dorothy ask for something... maybe food?  E2 swooped down to check the cache area but found nothing there so he flew out over the Frick Fine Arts Building, quickly caught a small bird and came back to the CL with it.  He flew in circles near the building and called to Dorothy.  When he got her attention, he switched the prey to his beak and she flew off the building and did a prey exchange with him (courtship!).   She took the prey back to her perch and he flew in and mated with her.  Lots of excitement.  More eggs coming soon.

Update, Thursday March 17, 1:25pm:  More excitement at lunchtime.  While I was walking toward the Cathedral of Learning (CL), a Coopers Hawk passed by the CL and four red-tailed hawks jockeyed for territory over Carnegie Museum.  In the midst of this Karen and I saw a second female peregrine fly near the Cathedral of Learning!  E2 flew off the CL and warned her away; she flipped upside down and showed her talons.  Meanwhile Dorothy was wailing a warning and then zoomed off the nest to chase her away to the west.   E2 waited on the lightning rod and did some territorial flights around the top of the CL.  It didn't take long for Dorothy to complete the chase & return to the topmost roof location above the nest.  As a show of strength they mated there.  Then Dorothy resumed circling, wider & wider to claim her territory.  I could see the extra peregrine disappear to the southwest.  Whew!  We're very glad everything is back to normal now.

(photos from the National Aviary falconcam at the Cathedral of Learning)

Mid-March Phenology

As I walked to the Cathedral of Learning at lunchtime yesterday, I made a list of all the new Spring things I found despite the chilly weather:

  • Crocuses blooming at Schenley Plaza.  These, in fact.
  • House finches, northern cardinals, robins and song sparrows all singing.
  • Male common grackles puffing up and saying "Skrinnk!" to each other.
  • European starlings singing songs that sound like killdeer and meadowlarks.
  • More dark-eyed juncoes than before -- they're on the move.
  • A bright ice halo around the sun that became a sundog.
  • Ducks and geese migrating.  (Saw a tundra swan fly north, high over the Cathedral of Learning)
  • Spring peepers and woodcocks at Middle Creek last Sunday.  (none of those in the city)
  • Freezing nights and above freezing days.  It's maple sugar time.
  • Immature peregrine falcons wandering and migrating.

Do you have a list of Spring things you've seen lately?  Leave a comment to let us know.

And about that last item in the list:  While I was observing the halo around the sun I saw a peregrine falcon fly in from the west very high up, nearly a dot.  The bird came a little lower as it approached the Cathedral of Learning (CL) but it was still quite high when it saw E2 and Dorothy mating near the nest.  It then passed over the CL to the east and used thermals to rise higher and higher. From below it looked dark, perhaps a juvenile.  When it was a tiny dot in my binoculars it moved off to the north.  I'm glad it was no threat to my two favorite peregrines. It was just passing through.

(photo by Kate St. John)

p.s.  Here's a definition of phenology and a list for Western Pennsylvania.
p.p.s. This is my 1,000th blog entry.

Meanwhile, at the Gulf Tower

On Saturday (the day before Dorothy laid her first egg at the Cathedral of Learning) our other peregrine falcon pair, Dori and Louie, were doing many courtship flights over Downtown Pittsburgh.  Sharon Leadbitter filmed them from her office at the U.S. Steel Tower and sent photos and a video.

The photo above points out that Louie is perched on the Kopper's Building and Dori on the Gulf Tower on the corner above the nest. 

Here's a closeup of Louie on the Koppers Building roof...

...and Dori on the Gulf Tower.

See Sharon's video of them flying here.  

Sharon wrote: They both seemed to be watching the St. Patrick's Day parade.  😉 

(photos by Sharon Leadbitter)