Archive for May, 2008

May 12 2008

Sooooo Cute!!

Peregrine Falcon chicks, 12 days old, University of Pittsburgh, May 12, 2008I captured this photo on the Pitt peregrine webcam today and my first reaction was “They’re soooo cute!” 

These three little white birds are 12-day-old peregrine falcon chicks, Dorothy and E2′s nestlings at University of Pittsburgh.  They’re in the cute downy phase before they start to grow feathers. 

Such bright-eyed babies!  I’m amazed at how white they are.  Even their beaks are white.  And their feet are so large that they sit like little Buddhas with their toes in front of them. 

I can tell they ate recently.  There’s a bulge at the top of their chests showing their crops are full.  (Many birds have crops, a muscular expandable section of the esophagus where they store food prior to digestion.) 

Soon these babies will get sleepy and sprawl flat on their bellies.  

Eating, sleeping, growing.  That’s all they’re going to do until early June when they’re ready to ledge-walk and learn to fly. 

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May 11 2008

Cat versus Cow

Brown-headed Cowbird, female (photo by Chuck Tague)My friends will tell you this bird is a villain, a despoiler of songbird nests, a wrecker of warbler home life.  She refuses to raise her own young, foisting them off on unsuspecting foster mothers.  To make matters worse, she sneaks in and kills the foster mother’s own young so that hers have a better chance to grow up.

This is a female brown-headed cowbird

I don’t know why she won’t make her own nest.  Perhaps it’s because cowbirds are nomads, following cattle and buffalo herds to eat the bugs and seeds they churn up.  With the herd on the move, her own nest would be a few counties away in no time.

So Mrs. Cowbird picks on a species that’s slightly smaller and lays an egg at dawn when the warbler or sparrow mother is away getting food.  If she has time, Mrs. Cowbird kicks out the foster mother’s true egg.  Not only that, her egg usually hatches earlier so it gets a head start on its foster siblings.  They die, the cowbird lives.Catbird and Cowbird eggs (replicas)

Sometimes this sneaky plan doesn’t work. 

Gray catbirds are able to recognize their own turquoise eggs.  Cowbird eggs are slightly larger and blotchy white as shown in the composite at right.

When a catbird finds a cowbird egg in her nest, she throws it out. 

In the battle of Cat(bird) versus Cow(bird), the Cat wins.

(photo by Chuck Tague)

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May 09 2008

Messy nest!

Dorothy gives up on housekeeping.  Peregrine falcon nest, University of Pittsburgh, May 8, 2008I’ve watched the peregrines at University of Pittsburgh for many years and have learned something about Dorothy, the falcon who nests there: she is not the best of housekeepers. When she has chicks to feed, cleaning her nest is a low priority.

This trait is individual to Dorothy’s “personality.” If you observe other peregrine nests on webcams, you’ll see that the gravel is usually pretty tidy.

Until yesterday I had hopes Dorothy had changed her ways. Perhaps E2 was having a positive influence. As recently as Wednesday evening the gravel was clean (see photo, top right).

Not so on Thursday! It rained all day and Dorothy gave up. In the second photo the nest is carpeted in prey feathers and the chicks are surrounded by a mess. As my friend Kate says, “Well, that’s what happens when you have young kids.”

Beth Fife of the Pennsylvania Game Commission will have her work cut out for her when she comes to band the chicks this spring. Every year Beth not only has to collect the chicks while Dorothy attacks, but she must drag a garbage bag out on the ledge and clean Dorothy’s nest.

For now, it looks like another messy year. Perhaps Dorothy thinks that Beth provides room service. (NOT!)

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May 08 2008

Best Bird in Ohio

Published by under Migration,Songbirds

Prothonotary Warbler (photo by Chuck Tague)I saw a lot of birds in northwestern Ohio last weekend - in fact the count of species may have been a personal record – but the best bird by far was this beautiful prothonotary warbler.  He was so stunning he attracted a crowd. 

This picture may make you think the prothonotary perches out in the open all the time, but don’t be fooled.  Though his bright yellow body is easy to see before the leaves come out, he forages low on branches in woody swamps and spends his time walking among the tangles.  It took a lot of snapshots and patience before Chuck Tague got this picture. 

Seeing a prothonotary warbler is always a treat, especially because I’m from Pittsburgh.  These warblers are southeastern birds whose northern range extends to the Great Lakes, but they don’t spend any time here.  Their favorite habitat is flat land in wooded swamps, a setting notably missing from southwestern Pennsylvania.  The only place I can reliably find them is in the glaciated area near Pymatuning.  And then I’m lucky to see one even there.

All of which makes this warbler the Best Bird and my favorite memory of last week’s trip to Crane Creek and Magee Marsh, Ohio

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May 07 2008

How much does a peregrine nestling grow in a week?

Comparison of peregrine nestlings on hatch day and one week later, University of Pittsburgh nestIt’s been a week since 3 peregrine eggs hatched at the University of Pittsburgh and their parents have been feeding them frequently. 

Have the nestlings grown?  Here’s a visual comparison.

At left are two photos from the webcam, exactly the same size.  The top photo shows the chicks on the day they hatched, the bottom one shows them today. 

Indeed, they have grown.  Each chick is two or three times larger than the remaining egg and the group of chicks takes up a noticably larger portion of the picture. 

Meanwhile the unhatched egg is already a week beyond its probable hatch date.  This egg is unlikely to hatch at all, but don’t worry.  In the seven years Dorothy has nested at Pitt she always lays 4 eggs but about 40% of the time she hatches only 3 of them. 

This outcome is normal.  Eventually one of the adults will move the unhatched egg out of the way.  

At the rate the chicks are growing, they’ll need all the space they can get!

Watch the peregrines in action on the National Aviary webcam. 

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May 05 2008

Why do they nest near us?

Juvenile peregrine Downtown Pittsburgh, summer 2007Several people have asked me why birds of prey, especially red-tailed hawks and peregrines, would choose to nest close to humans. Isn’t it unnatural? Doesn’t it make them tame? Are the ones who nest on buildings already tame?

In the case of peregrines, whom I know better than red-tails, I can tell you it never makes them tame. To them, we are still their mortal enemies. Instead, conscious or not they have made a calculation: The enemy of my enemy is my friend… and besides, there’s lots to eat.

Birds of prey know that humans can and do hurt them but they also know from personal experience that it is rare. Meanwhile, they have learned there’s an advantage in being near humans because we keep their other enemies away.

A good example is that great-horned owls, a dangerous predator of peregrines, are rarely if ever found on office buildings. Peregrines who nest on buildings have one less worry as they raise their young.

Another advantage is the food we generate. Humans create a lot of garbage and many prey species eat it. For red-tailed hawks, we indirectly provide rodents. For peregrines, our buildings house pigeons and starlings, a ready food supply.

When their nests are successful their hunch about us is reinforced. The juvenile peregrine in the picture is a case in point. She was born in downtown Pittsburgh on the Gulf Tower in April 2007. Her parents made the calculation that the territory was safe with plentiful food and they successfully raised four young birds. As you can see, she was thriving last July when her picture was taken by Matt Frederick as she perched on Roberto Capriotti’s windowsill at K&L Gates in the Oliver Building.

If these birds can put up with seeing humans every day, the rest is easy.

p.s. I wish she’d landed on my windowsill… but if she had, I would have been unable to concentrate for the rest of the day!

(photo by Matt Frederick)

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May 03 2008

Birding with friends, making friends with birds

Bay-breasted Warbler (photo by Chuck Tague)For a peregrine fanatic this is a hard time to be away from Pittsburgh – what with baby peregrines in two nests and lots to watch – but migration is in full swing and the warblers beckon. There are lots of birds flying north, birds who barely stop to eat on their way to Canada, and I don’t want to miss them.

That explains why I’m at a Magee Marsh in Ottawa County, Ohio with Chuck and Joan Tague right now and we are looking at beautiful warblers. For many Pittsburgh birders a May pilgrimage to northwestern Ohio has become a tradition.

Last year when we made this trip we also took the ferry to Point Pelee, Canada, a sand spit that points south into Lake Erie. It was foggy the whole way and we were barely able to see the islands as we made the crossing. At the tip of the peninsula in Canada we found warblers galore. They too had made the foggy crossing and were desperate to eat before flying onward to their homes further north.

This bay-breasted warbler was so busy eating that he didn’t care that we watched him. He had completed most of his journey from Venezuela to Canada’s boreal forest and he was hungry. He walked the branches at eye level and cocked his head while Chuck Tague took his picture. Then he followed as we continued our walk. It was almost as if we’d made friends with him.

Not really. But the warblers do come this close during migration along Lake Erie’s shore. That’s why I’m here.

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