Monthly Archives: March 2009

Which is which?

Peregrine mates take turns incubating: male (E2) on left, female (Dorothy) on right (photo from National Aviary webcam at Univ of Pittsburgh)When I describe the activities of the Pitt peregrines people often ask me, “How do you tell them apart?  Which one is Dorothy?  Which is E2 (the male)?”

Unlike many songbirds male and female peregrine falcons look alike.  The main difference between the sexes is their size – the female is up to 30% larger than the male – but this is only useful when you see them side by side.  Even then they can fool you if the male has puffed out his feathers and the female has not.

So how to tell?

Thanks to the webcam at the University of Pittsburgh nest we’re able to take a closer look and – this may sound incredible – Dorothy’s and E2’s faces are different.  When you know what to look for they’re recognizable just the way humans are. 

To show you what I mean I captured some screenshots of both birds in similar poses and placed them side by side.  In the composite above E2 is on the left, Dorothy is on the right.   (There is another composite photo too, if you click on this one.)

First, the easiest sign:  Look at their foreheads.  E2 has a line of white feathers where his beak meets his forehead.  Dorothy’s forehead is all gray.  Last year I remarked that the yellow on E2’s beak looked “longer” but it’s his white forehead that causes that illusion.  (Thanks to Nora on the Cleveland Falcon Forums for putting a name to this feature.)

Expanding the comparison: Look at their heads.  E2’s looks more square or angular, partly because of his white forehead, and his eyes aren’t in shadow.  Dorothy’s head is rounder on top, her eyes are more deeply set and her eyebrow line is sharper.  My friend Karen says this makes Dorothy’s eyes look fierce. 

Finally, it’s clear in the composite photos that E2 is smaller than Dorothy.  When he sits in this position his tail lies flat on the gravel while Dorothy’s body is so long that her tail hits the back wall of the nest box and she bends it to the side.

Armed with these clues you’ll have many chances to observe Dorothy and E2 as they incubate their eggs in the coming weeks.  See if you can tell the difference. 

Keep in mind the facial differences apply only to these individual birds, not to all peregrines, and that you would never see this without a webcam.  When peregrines fly or perch the only way to tell the sexes apart is by their size.

(photos from National Aviary webcam at University of Pittsburgh)

Sounds of Spring

American Robin in the rain (photo by Chuck Tague)Even before dawn I could hear the robins singing.   Last night a large flock filled the trees near my house and sang their very best songs.  I thought they would leave overnight but they were here to greet the morning, too.

I stepped out on the front porch in the dark and was immediately surrounded by birdsong.  Lightning glowed in the southwest.  The robins sang on.  I went indoors for coffee.

While I was inside the storm arrived but it was mild.  Rumbles of thunder, rain tapping on the roof and windows, water gurgling in the gutters.  A lone robin continued singing in the rain.  What an audio feast! 

The storm has passed.  A sunbeam gleams on the city skyline five miles away.  The robins are singing again joined by song sparrows, cardinals, juncoes and chickadees.  The local crows caw as they regroup. 

Today’s rain precedes a cold front – maybe snow showers tonight.  What a joy to have heard the sounds of spring.

(photo of an American Robin by Chuck Tague)

Bold as you please!

While I was at work yesterday The Squirrel destroyed part of my new expensive bird feeder.

I bought it because the squirrels had eaten my old wooden ground feeder and gnawed its wire pigeon-proof cover into sharp thin tines.  The new feeder is all metal and has a spring-loaded perch so that when a heavy bird (pigeon) or a squirrel stands on it the cover closes and hides the bird seed.

Don’t get me wrong.  I don’t mind if the squirrels eat some seed but I have to deter them or they wolf down everything.  They’ve enjoyed my largesse to the point that I now have five of them sparring over access to the peanuts in my “No Mess Mix.”

So I thought I was safe and felt really, really smart when I brought home this crafty feeder.

If I was a squirrel however, I would have noticed that the most important component – the perch – was made of wood.

Last evening I found the situation pictured above.  The feeder was missing its perch, the perch was in bits on the ground and The Squirrel was picking through the bits eating the seeds he’d knocked out of the feeder.

As I investigated I discovered he didn’t do this without personal sacrifice.  He left behind one of his claws in the closed cover.  Ow!  I’ve noticed that the normal rodent (squirrel) reaction to being stuck anywhere is to chew one’s way out of it, so the perch might have been an innocent bystander caught in the crossfire.

I couldn’t leave the feeder without a perch.  The birds were milling around trying to figure out how to eat when there was nowhere to stand, so I found a dowel among the wood scraps in the basement and taped it in place.

This will have to do until I can construct a better solution.  Maybe the manufacturer supplies replacement perches at Wild Birds Unlimited.  I can’t be the first person who has The Squirrel in her back yard.

(photo by Kate St. John)

Four eggs at Pitt

This morning there are four eggs at the University of Pittsburgh peregrine nest.  Many of you saw the eggs when Dorothy got up at about 8:15am.  E2 arrived almost immediately so it was a very brief glimpse.

Then at 8:30am Dorothy came back and the two of them bowed over their eggs before she sat down again. 

This is likely to be her complete clutch – but you never know.

(photo from the National Aviary webcam at Univ. of Pittsburgh)

Coming Soon

Tree Swallows gather for migration (photo by Chuck Tague)Last Sunday I drove up Interstate 79 to Moraine State Park, hoping to duplicate the wonderful bird moments I experienced there a week ago. 

Right off the bat I encountered a huge flock of  migrants.  More than three quarters of my fellow interstate travelers had Ontario license plates and for several miles I was the only Pennsylvanian.  The first day of spring must have triggered Canadian migration.  If people were on the move I expected a lot of birds.

When I got to Moraine the lake was like glass.  No wind.  It was easy to see birds on the water because every ripple showed but most of them were too far away to identify, let alone enjoy.  I picked through the nearby coots and ruddy ducks and then I was done.  My mind said, “There’s nothing here.”

Of course I was wrong about that.  There were birds out there, but I’d set my expectations too high – again!  There’s nothing like a long hike to flush a bad attitude out of my system so I went to Muddy Run.

In mid March there are far fewer birds in the woods than on the water, but I don’t care – there are frogs!  There’s nothing quite so magical as walking alone through a quiet landspace surrounded by the jingling sound of spring peepers.  While I hiked their voices were never close.  The peepers felt my tread and went silent as I approached, then resumed behind me as I walked away.  I was in a bubble of silent frogs surrounded by a ringing chorus.

Soon the wood frogs joined in.  I was prepared to hear their quacking sounds but forgot how much they resemble ducks.  Wood frogs are even more wary than peepers so I didn’t even attempt approaching them. 

So two late-March phenology predictions had come true.  Was there a third?

Twelve days ago Chuck Tague sent me this photo of a large flock of tree swallows at Lake Woodruff, Florida gathering in preparation for their migration north.  I hadn’t seen any tree swallows in Pennsylvania this year.  Were they here yet?

The wind picked up and blew hard over the water.  Then I saw them, my first-of-year tree swallows, only three flying fast into the wind.  The rest are coming soon.

(photo of tree swallows at Lake Woodruff by Chuck Tague)

The Big Sit

Female peregrine incubates her eggs at Gulf Tower, Pittsburgh, 2009 (photo from National Aviary webcam)

When birders talk about The Big Sit they’re referring to a 24 hour birding event in October where participants sit in a 17 foot diameter circle and count every bird species they see and hear.

I have never done a Big Sit but when I watch the peregrines incubating their eggs on the webcams I am in awe.  How do otherwise active birds manage to sit there for four and a half weeks?

Peregrine falcons begin incubation when they lay their next-to-last egg in the clutch, then sit for 33-35 days until the eggs hatch.  Even then the work isn’t done.  Peregrine chicks cannot immediately regulate their body temperature so the parents must brood the chicks for an additional week.  All told, that’s five and a half weeks of sitting.

Tasha, the female peregrine at Gulf Tower shown here, began her Big Sit on March 17.  (This post was written in March 2009.)  Dorothy, at the University of Pittsburgh site, will begin in earnest when she lays her third egg.  (Dorothy typically lays four.)

Who incubates the eggs depends on the species.  Among mallards only the mother bird sits on the eggs but in peregrines both parents play a part.  The mother peregrine incubates all night and most of the day.  Her mate brings her food and incubates while she eats and flies a little to stretch her wings.  Then she’s back on the eggs.  How long her mate spells her and how often depends on the individuals.  I’ve noticed at Pitt that E2 gives Dorothy a break at least twice a day: at dawn and in the late afternoon.

Because they incubate, both male and female peregrines develop a brood patch, a spot of bare skin with blood vessels close to the surface.  The brood patch isn’t visible when they fly because nearby feathers cover it but it’s an opening for heat loss so it regrows feathers as soon as it isn’t needed.

Much as I like peregrines, watching them incubate eggs is about as exciting as watching paint dry.  Barring an unusual event, there won’t be much to see at Gulf Tower until hatch day which will probably be April 19th.  At Pitt, we’ll have some excitement as Dorothy lays two more eggs but she too will start The Big Sit.

News update March 23 at 3:10pm:  Dorothy laid her third egg at about 3:10pm.  If this is her next-to-last egg (which it very likely is) she has just begun her Big Sit.

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