Outside My Window

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 (photo by Chuck Tague). 

I don’t know why she won’t make her own nest but 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.

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.

I’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!)

Several 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!

It’s been six weeks since the first common grackles came back to Pittsburgh for the summer.  (We don’t have great-tailed grackles; they’re a southwestern bird.)

In the beginning the flocks were made up of males who came early to work out the pecking order before the ladies arrived.

In early April the females started to trickle in.  At first they were in such small numbers that the males outnumbered them and there were loud chases - three guys for every gal.

Now the balance has swung to 50-50.  The ladies are here and the guys are getting down to the serious business of courtship.

I could tell how far the grackle nesting season had progressed when I saw a pair of common grackles courting in a tree near my house.  The male puffed himself up and said “Skreeeeeeeek!”  The female fluttered her wings and said “ee ee ee ee ee ee ee.” 

It must have done the trick because they mated.  More grackles will soon be in the making.

I heard an unusual bird song the other day - a quiet wiry whistling, almost a melody.  I suspected it was a robin, but this was a new sound to me so I stopped to find the bird. 

Indeed, it was a male robin and he moved away at my approach but he didn’t stop singing.  Instead he stayed close to his audience, a female robin.  With his beak pointed up and wide open, he whispered his song to her and watched for her reaction.

Was this courtship?  I did some research in my bird books and on the web and found only a few hints.  Even though robins are very common birds, their courtship activities aren’t distinctive enough to be described any better than “two birds hanging out together.” 

Here were two birds hanging out together and maintaining eye contact while he whispered sweet nothings to her.  Who knows?  On a cold March day that might be the extent of robin courtship.

Spring wants to come early to Pittsburgh but it can’t make up its mind.  Two days ago it was 60^oF.  In two more days the temperature will dip to 11^oF.

The birds are conflicted about the season too.  In winter, northern cardinals feed peacefully together as pictured here by Marcy Cunkelman, but in spring they get quite aggressive and territorial. 

This morning during my walk to work I saw three cardinals - two males and a female - having a dispute in a front yard on Forbes Avenue.  All of them were making loud chip calls and chasing each other in circles.  Perhaps one of the males was trying to lure the lady away.  No more peaceful coexistence for them!

In spring, cardinals literally “see red” when a rival appears on the scene.  During the nesting season they will even attack a mirror, trying to rid the area of that red bird in the glass. 

They warm up to courtship with other behaviors too.  If you watch at a bird feeder, you may see the male pick up seeds and feed his lady - a welcome change from his cranky attitude toward her in December. 

You might even be lucky enough to see them counter-sing. 

In most songbird species only the males can sing, but female cardinals don’t have this limitation.  When the pair counter-sings, they perch in different areas of their territory.  First one sings a phrase, then the other repeats it.  The first sings again and the other repeats again.  The first singer may alter the phrase.  The other repeats the new phrase.

Cardinal pairs may spend a good part of the day counter-singing but you have to see them doing it to know it’s a pair instead of two males claiming nearby territories.

Counter-singing is a beautiful thing to watch.  I have only been lucky enough to see it once.

Outside my office window in the afternoon, I see flocks of crows, robins and starlings heading for the roost.  Lately it occurred to me that I’m able to identify them at a glance, not by looking at the individual birds but by looking at the shape of the flock.  This skill was particularly useful at the robin roost on January 6 because it was too dark to see individual birds.  

As you can see in the pictures above, the flock shapes can be different even in birds of the same size.  From left to right are four flocks:  American robins, European starlings, double-crested cormorants and tundra swans.  (First two photos are by Tom Pawlesh, last two by Chuck Tague.)

Here are some flock shapes I can think of: 

• American robins: loose flock, widely spaced.  Each bird maintains the same relative position within the flock.
• Starlings and pigeons: tight flock, synchronicity. Every bird makes the same move at the same time.
• Double-crested cormorants:  J-shaped flock or a long line.  The flock looks scraggly.
• Geese and swans:  V, J or crescent-shaped flock.
• American crows:  A loose flock in which each bird has his own idea about where he wants to be.  Individuals show considerable positional movement within the flock.  The birds look like black rags flapping in the sky.
• Blue jays:  A loose flock so widely spaced that they sometimes look like they’re not traveling together.  Individuals maintain the same relative position within the flock.
• Cedar waxwings and American goldfinches:   The flock moves in unison but individual birds change position within the flock, mostly by moving up or down.  American goldfinches say “potato chip” as they fly.
• Small finches, common redpolls:  Fly fast in relatively tight flocks.  The flock moves in unison.  Individuals zip forward or slow down but maintain positional integrity. 
• Cowbirds: have a cool hopscotch pattern as they sweep across a field searching for food.  (comment from Chuck Tague)
• Brown pelicans: The flock travels in a long line, skimming the surface of the ocean.  They will even skim the surface of high rise buildings at the beach.  Each bird synchronizes wing movement with the flock:  first bird flaps downward, then second bird, then third, then fourth…
• On water American coots huddle close together in an extremely dense flock in the presence of a bald eagle.
• Turkey vultures:  Soaring birds.  Each bird goes his own way but they stay together.  They hate to flap.
• Cranes: Soaring birds who travel in flocks, sometimes in a loose V.
• Hawks and falcons:  no flock at all.

An animal-lover friend of mine began to feed the birds and was shocked when a coopers hawk killed a mourning dove at her feeder.  She does not eat meat and wanted to know if she could train the coopers not to eat meat either.  “If I put out more corn, will he eat the corn and not the doves?”

“No,” I said, “he will not eat corn.  He’s a carnivore.  That’s just how it is.”

Because humans are omnivores and we grow our own food, we find it hard to imagine the lives of creatures who must hunt to live.  If a coopers hawk is not an efficient hunter, if it does not kill birds, it will die.  It would be cruel to the hawk if it could not hunt. 

But what about the prey species?  Is it cruel to them that they are hunted? 

There is a beautiful poem by James Dickey in which he describes the heaven where wild animals go.  Called The Heaven of Animals he describes the predators in their heaven crouched on the limbs of trees and writes,

“And those that are hunted
Know this as their life,
Their reward: to walk

Under such trees in full knowledge
Of what is in glory above them,
And to feel no fear,
But acceptance, compliance.”

The universe is structured so that everything is eaten by something - in the grave, if not before. What an amazing cycle.

That’s just how it is.

As I write there’s a tremendous racket going on in my neighbor’s back yard. The blue jays are screaming and jumping around in the spruces, focused on a spot I cannot see.  Starlings are loafing nearby to see what happens.  Twelve nervous mourning doves are sitting in the black locust.  The juncoes have joined the fray in the spruces, even though they’re normally wary of jays. 

Everyone’s excited about a predator in the spruces.  I can only guess it’s an eastern screech-owl.

Blue jays are an excellent alarm system.  I often use their calls to find birds of prey.  Small birds are saved the surprise of being eaten when they hear the jays’ alarms.  Even though the rest of us benefit from them, the jays just view it as doing their part to make the world safe for blue jays.

At rush hour last night, a river of crows flew over Fifth Avenue and perched in the trees on Wilkins.  That event and last week’s robin roost prompted me to think about flocking behavior. 

We’ve all noticed that birds flock in winter.  It turns out that flocking is usually a trait of social species, such as crows and parrots, and species whose food sources are abundant: omnivores like gulls and starlings, seed-eaters like blackbirds and finches.  But why to they do it?

The first reason is defense.  It’s harder to be caught unawares if you’re in a flock with many watchers and it’s statistically quite safe.  At the robin roost we heard a pair of great-horned owls but each owl will catch only one bird per night, leaving an individual robin with a 0.002% chance of becoming an owl meal.

Another flock advantage are the many eyes searching for food.  If the food source is abundant - a seed field or a landfill - everyone gets a meal.  Obviously, flocking doesn’t work for birds like red-tailed hawks who catch their prey by stealth. 

Social species enjoy flocks.  Crows get smarter by being with each other.  As Candace Savage said in Crows: Encounters with the Wise Guys:  “Nothing is more intellectually challenging than living in a social group, surrounded by a bunch of other animals that are sharpening their wits on you.” 

The most spectacular flocks are made up of starlings who wheel in unison without an apparent leader.  Tom Pawlesh took this photo of a spectacular “cloud” of starlings.  Not all birds fly in a tight formation like this.  When it comes to flocking, starlings are the champs.