Outside My Window

Song is an important territorial and mate-attraction signal for birds so how do they cope when there’s a lot of noise?

Many songbirds abandon noisy settings but some can handle it by changing their songs.

Dr. Clinton Francis of the National Evolutionary Synthesis Center in Durham, NC studied two species of western vireos in noisy areas and found that both altered their songs so they could be heard. 

Gray vireos (Vireo vicinior) sang longer songs and raised the pitch of their highest notes while plumbeous vireos (Vireo plumbeus) sang shorter songs and raised the pitch of their lowest notes.

Where do these birds live that it’s so noisy?  Near natural gas compressor stations in rural New Mexico.   The compressors roar non-stop at more than 95 decibels. 

Pennsylvania has a lot of compressor stations in Marcellus Shale drilling areas.  Maybe Dr. Francis will study our birds.

Read more here in Science Daily.

And here’s a similar study done in Colorado.

(photo by Clinton Francis of the National Evolutionary Synthesis Center, linked from the Science Daily article)

Is this bird sleep deprived?  And if so, how does he make up for it?

Several years ago the Max Planck Institute for Ornithology answered these questions by studying sleep in pigeons. 

Prior to the study, they knew that birds experience two phases of sleep — slow wave sleep (SWS) and rapid eye movement (REM) — just like mammals do. 

SWS is deep, dreamless sleep during which the brain shows synchronous, slow oscillations of neurons as shown on an EEG (electroencephalogram).  SWS alternates with dreaming sleep, called REM (rapid eye movement) because the eyes move rapidly during this period even though the lids are closed.  

To study sleep in pigeons researchers prevented the birds from taking naps, something they like to do late in the day.  (I do too!)  

The pigeons were allowed to sleep normally at night when researchers learned that the birds made up for their sleep loss by more intense periods of SWS.  Their slow-wave-sleep lasted the same amount of time as before but during SWS the number of slow waves was much higher.  In other words, they slept more deeply.

Mammals do this too under similar conditions.   We all “power sleep” when especially tired.

So what did the pigeons think of this experiment?

I’ll bet it made them grumpy.

(photo by Derek Ramsey (Ram-Man) licensed via Wikimedia Commons. Click on the photo to see the original.)

Peregrine falcon chicks and baby robins aren’t the only ones learning how to fly right now. 

This year’s “baby” red-tailed hawks are learning too.   They’re the same size as their parents but they’re clumsy fliers and often have trouble landing.

Even when they fly well enough to follow their parents they don’t know how to hunt.  In this they have a lot in common with the young peregrines at Pitt. 

How to get a meal?  Ask mom and dad!   Make sure they know you’re hungry!  Make sure they notice you!

The juveniles of both species spread and wave their wings to attract their parents’ attention.    ”Look at me!  I’m starving!”

And they whine a lot!  Young red-tails and peregrines are both so loud that people often think they’re hurt.  On Tuesday at Pitt the whining of just one peregrine chick on a 32nd floor ledge of the Cathedral of Learning was so loud I could hear it a quarter of a mile away on Craig Street!

Immature red-tails easily attract human attention even when they can hunt on their own.  One summer I saw a young red-tail whining while he was hunting.  He perched on a fence and whined at a mouse in the grass while he waited for the opportunity to pounce on it.  The mouse escaped, of course.

Don’t be surprised if you see and hear young red-tailed hawks in the next month or two.  Neil Gerjouy found this one waving his wings in Point Breeze last summer. 

(photo by Neil Gerjuoy)

Steve Valasek sent me this photo of a raven landing and said, “We visited Acoma Pueblo on Monday and saw many ravens riding the updrafts on the sides of the mesa.  Our guide said that he’s actually seen them fly upside down.”

You bet they fly upside down!

Ravens are very acrobatic fliers.  I’ve seen them tumble together many times as they launch over the cliffs at Acadia National Park in Maine.  They seem to get a lot of joy from doing this and might even be competing to see who can make the best moves.

It’s so hard to describe how cool they are that I found a video of ravens sky-tumbling at Lundy Island, Great Britian.  Watch carefully at 29, 40 and 44 seconds and you’ll see one of them completely flip over sideways.  Awesome!

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Ravens are cool, but for speed you can’t beat a peregrine.  While searching for the first video, I found this one of a peregrine  harrassing two ravens at Culver Cliff, Isle of Wight.  The big soaring birds are ravens.  The very fast, smaller, flapping bird that appears from above at 3 seconds and 13 seconds is the peregrine.

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Let’s tumble!

(photo by Steve Valasek)

For days now we’ve been focused on birds who eat birds (peregrines, for instance) without thinking much about the lives of the birds who become dinner. 

Fortunately for them, small birds have several defense mechanisms for avoiding birds of prey.  To avoid a peregrine in the city, they stay low.  To avoid other hawks they say in thick cover.  When there’s no cover handy they freeze in position, hoping the predator won’t notice them.

Here’s a pair of downy woodpeckers at Marcy Cunkelman’s house, frozen on her porch railing to avoid being seen by a passing hawk. 

Don’t move! 

The hawk didn’t see them.  It worked.

(photo by Marcy Cunkelman)

Courtship is well underway among Pittsburgh’s resident birds.

On sunny days red-tailed hawks seem to be everywhere, soaring to claim territory and court their mates.  Sometimes you can’t tell the difference between courtship and chasing.  Is he driving away an intruder or impressing his mate?  And, my heavens, his scream sounds scary!  (Read more about red-tail courtship here.)

Because I love watching peregrines and hawks, I often pay attention to their favorite food: pigeons.  That’s how I noticed that rock pigeons make courtship flights, too.

Most of pigeon courtship occurs on the ground but there are two flight behaviors that tell you they’re courting. 

The first is wing clapping in which a pigeon takes off from the flock making a loud snapping sound as he claps his wings together at the top of his upstroke.  This behavior is usually initiated by a male to advertise his sexual maturity.  His action often prompts other members of the flock to take off and clap their wings as well.

The other display occurs when a pair breaks off from the flock in flight.  Eventually one or both will soar with their wings held upright in a stiff V.

I’ve sometimes seen a trio break away and fly together but only two of them do the V flight.  I’ll bet these trios are one female with two males and the guys are trying to impress her.  It certainly looks less dangerous than what red-tails do!

(photo from Shutterstock)

…not everything nice.

On my walk to work Tuesday morning I witnessed a territorial battle between female northern cardinals that was fierce and possibly bloody.

My attention was drawn by three cardinals chasing, chipping and wing flashing in a thicket.  Two females were fighting and a male was keeping up with them.

One of the females was clearly stronger than the other but the weaker one would not give up.  I could see she was frightened but even as she avoided her attacker she sometimes sang the cardinal song. 

Unlike most female birds, female cardinals can counter-sing with their mates.  Was she singing for the territory?  Was she asking the male for help?  I could tell there was not much he could do.

The group chased through the thicket, then both females dropped out of sight into deep ivy.  I thought the fight was over.  Instead it was more intense.  When they emerged from the ivy the stronger female was biting the weaker one on the neck.  Ow!  Ow!

By now the weaker cardinal had had enough.  She broke away and flew low across Forbes Avenue in front of traffic.  I watched with horror as she nearly was hit by a Port Authority bus.

But she made it.  She was safe. 

I felt like a limp dishrag.  She nearly died!  I didn’t know how much I cared about the drama until my adrenaline was gone. 

Little girls may be “sugar and spice and everything nice” but that’s not what this bird is made of.

(photo by Cris Hamilton)

Back in January I posted a photo by Marcy Cunkelman in which a female cardinal stood with one wing straight up as a male cardinal flew toward her.  Here’s a cropped version of that photo.  (Click on the photo to see the original.)

Many of us wondered what this wing message meant.  Well, I just found out.

Donald and Lillian Stokes call this behavior the “lopsided pose” in their Guide to Bird Behavior.  It’s a courtship display(!) in which a male or female cardinal tilts one side of its body up, raises its wing and exposes its belly.

According to Stokes, this is usually done within sight of the mate who is only a few feet away. Sometimes they both do it together but it happens so fast we don’t normally see it. 

So, despite appearances this doesn’t mean “Back off, buddy.” 

She’s saying “I love you!”

(photo by Marcy Cunkelman)

Now that the birds are singing again I’m intrigued by news of birdsong.

Just this week I learned that a study found that teenage male birds sing better when the “girls” are around.

Songbirds learn their songs as they mature.  They babble as babies and improve as they get older. 

Scientists at University of California San Francisco decided to find out how birds learn this skill by recording teenage male zebra finches singing under a variety of social conditions.

As expected the ”boys” could sing, but not very well.  When alone they sounded immature.  But the researchers were surprised that in the presence of a female the boys sang much better, almost like adults. 

“The birds picked the best version of the song that they could possibly perform and they sang it over and over again,” said senior author Allison Doupe, MD, PhD in Science Daily.

The study found that social cues improved the birds singing skills faster than when they practiced alone.  Ultimately, this finding may provide new ways to improve speech therapy for humans. 

It also shows that teenagers are the same the world over.  Even among birds, the boys show off for the girls.

Read more about the study here in Science Daily.

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

 
In March Pittsburgh’s peregrines engage in courtship rituals that cement their pair bond. 

Some are the courtship flights I described on Monday.  Others are “familiarities on the cliff” that peregrines do while their mate is nearby on the cliff or building.

These familiarities, also called ledge displays, can take place elsewhere but as egg-laying time approaches the pair usually performs them at the nest. 

You’ll see these activities on the Gulf Tower and Cathedral of Learning falconcams.  Here’s what to look for:

The male has a ritual that he does alone.  In it, he tries to entice his mate to join him at the nest by swaggering onto the ledge and walking to the scrape with a high stepping tip-toe gait.  He then stands in the scrape, high on his legs but with his head bowed, and calls to his mate.  He makes scraping motions with this feet, then pauses and looks at her as if to say, “Will you join me?” 

How long he continues this display depends on her reaction.  If you watch the Gulf Tower falconcam you’ll see that Louie is a master at this activity and he’s quite loud about it.  It’s a wonder that Dori hesitates at all when Louie’s so insistent.

When his mate joins him at the nest the pair engages in a mutual ledge display like the one Dorothy and E2 are doing above at the Cathedral of Learning. 

In this ceremony they bow low together over the scrape and say “ee-chup, ee-chup,” bowing repeatedly.  (The “scrape” is the bowl they make in the gravel where she’ll lay her eggs.)

In mid-winter when they first begin this ritual the bowing may last for only 10 seconds.  Then one of them leaves, usually the male.  In March when they’re only days away from egg-laying, the ceremony lasts longer and becomes more intimate.  The pair calls softly and twists their heads to opposite sides while they bow.  Sometimes they even touch beaks. 

That’s what Dorothy and E2 were doing last year at their nest when the webcam took this snapshot.  See how low she bows?  (She’s the larger bird on the left.)  See how her beak is open?  She’s ”cheep”ing to E2.

Watch the National Aviary falconcams and you’ll see what I mean.

(photo of Dorothy and E2 from the National Aviary’s webcam at the Cathedral of Learning)

p.s.  Have questions about peregrines?  See my Peregrine FAQs.