Archive for the 'Bird Behavior' Category

May 25 2014

Little Against Big

During the nesting season small songbirds chase large predators away from their eggs and young.  It’s a topsy-turvy time when the pecking order is reversed.

Sharon Leadbitter saw this in action last week at Allegheny Cemetery when a blue jay repeatedly bopped a red-tailed hawk on the head, trying to drive it away from his territory.

Eventually the blue jay was just too annoying ….

(video by Sharon Leadbitter)

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May 16 2014

How To Build A Robin’s Nest

Mid-May is the height of robin nesting season in Pittsburgh.  The first nestlings have hatched and some are ready to fledge.

On Thursday I saw my first-of-2014 robin fledgling in Schenley Park.  Last month his mother spent 5-7 days building his nest.  This video shows her process in only 8.5 minutes.

While Mr. Robin sings in the background, his mate brings dry grass and drops it into place.  Her project looks sloppy for a while, then she does a cool thing.  She rapidly stamps her feet inside the nest while holding the edges with her wings and tail.  This makes the cup exactly fit her body.  How cool is that!

Halfway through Mr. Robin comes for a brief inspection.  Since he neither builds nor incubates, the nest is of passing interest to him.

When the cup is complete Mrs.Robin lines it with mud, then adds fine bits of dead grass to make the nest soft and lays her eggs.  (The last two steps are not in the video.)

Robins raise two or three broods per year and usually build a new nest for each brood.

What a lot of trips back and forth!

(video on YuoTube by richpin56)

5 responses so far

May 14 2014

Fun Facts About Cigars With Wings

Chimney swift flying in Austin, Texas (photo by Jim McCullough, Creative Commons license, Wikimedia Commons)

The chimney swifts came back to town in April from their winter homes in South America. In this week’s hot weather they’re zooming high above the rooftops eating insects and courting.  If they’d only hold still you could see they look like cigars with wings.  Here are some fun facts about them.

Chimney swifts are “songbirds” but their song is a dry chittering sound, loudest when they’re courting.

They are small. Stretch out your fingers. From the tip of your thumb to the tip of your pinky finger is the wingspan of a chimney swift. If you have big hands, your hand is wider than the bird.

Chimney swifts can’t perch on a horizontal surface. Their legs+feet are shaped like garden claws so they can only cling upright to the inside of a chimney or hollow tree.

True to their name they nest in chimneys, constructing a half-moon cup of twigs glued to the wall with their sticky saliva. To gather sticks they grab dead twigs in flight with their feet and transfer them to their bills to carry home.  I have never seen a chimney swift carrying a twig.  It’s something to look forward to.

Though most mating occurs at the nest, chimney swifts can mate in the air!

The female lays 4-5 eggs which both parents incubate for 19 days.  Even though the chicks are born naked with closed eyes their feet are so well-developed that they can cling to an upright surface on the day after they hatch.

For such a small bird, chimney swifts live an amazingly long time, averaging about 4.6 to 5.5 years.  Some have lived to be 15.

Watch them fly and they’ll inevitably look as if their wings are out of synch, one wing up and the other one down.  This is an illusion caused by their rapid flapping and side-to-side turns.  If you added wings to a cigar it would do the same, but not as gracefully.

 

(photo by Jim McCullough, Creative Commons license on Wikimedia Commons. Click on the image to see the original)

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May 08 2014

Which One Should I Choose?

Trio of brown-headed cowbirds (photo by Dori from Wikimedia Commons)

Brown-headed cowbirds are courting now because their victims are about to nest.  The males sing a bubbly whistling song to attract a favored female.  After she’s chosen a mate, Mrs. Cowbird lays her eggs in the nests of smaller birds whose own eggs and nestlings die while the foster cowbird chick thrives.

In cowbird society nest building and incubation never occur so the pair bond is cemented by courtship songs and postures.  Amazingly, the quality of the male’s song really matters.  That’s how the female decides who to accept and who to ignore.

What happens if a female can’t tell the difference between good and bad songs?  What happens when one lady in the flock doesn’t follow the rules?  Last year scientists learned that one tone-deaf female can upset cowbird society.

Researchers at the University of Pennsylvania led by Sarah Maguire inactivated the song-control centers of some female cowbirds’ brains so they could no longer distinguish between high and low quality songs.  When placed in a mixed-sex flock these ladies reacted to all songs and did not stay with a chosen male for long.

Since male dominance among cowbirds is based on song quality the best guys usually get the best gals.  However, when a tone-deaf female appeared in the flock she listened to all males equally and the minor males got a boost.  The dominant males courted the altered female more vigorously.  The other ladies were left in the cold.

Which guy will she choose?  One tone-deaf female can mess up an entire social structure.

Read more here in PLOS One.

 

(photo from Wikimedia Commons, Creative Commons license.   Click on the image to see the original)

 

5 responses so far

Apr 25 2014

Smart Black Birds On Camera

Raven on nest at Wellesley College (screenshot from Wellesley College ravencam)

Tired of being outdone by celebrity bald eagles and peregrine falcons, ravens have decided to get into the act.

Last October a pair of common ravens chose Wellesley College as the smart place to be.  Over the winter they scoped out the campus and evaluated future nest sites.  By March it was evident they’d made a wise choice when they built their nest on a high fire escape at the Science Center.  Their platform is enclosed by glass on three sides so they have great views and less wind.

They also have electricity, an Internet connection and night lights — perfect for a webcam — so Pauline and Henry are now celebrities.

Named for the founders of Wellesley College, Pauline and Henry’s choice probably shocked the local raven population.  “What were you thinking!? Humans are unpredictably dangerous!  We never nest that close to them.”  But their unique choice has given them shelter while we get a window on their world.

Pauline laid two eggs in March, one hatched in early April, and now their nestling is growing every day.  Unlike peregrine falcon chicks, raven babies are not cute, fluffy and white.  Instead they’re born naked and awkward with a very large mouth.  When the parents come to the nest “the mouth” opens to show off its red interior.  In the weeks ahead the mouth will stay red but the body will transform into a feathered juvenile raven, one of the smartest birds on earth.

Smartly clothed in black, Pauline and Henry are happy to share their lives with you on camera.  Click here or on the screenshot above to watch them online.

 

(screenshot from the Wellesley College ravencam)

p.s. When ravens blink their nictitating membranes, their eyes look white.  Very cool!

4 responses so far

Apr 23 2014

How Parrots Name Themselves

Published by under Bird Behavior

In case you missed this featured video at the Cornell Lab of Ornithology

Did you know that baby parrots name themselves and that parrots call each other by name? This 2011 video from Cornell Lab is fascinating!

 

Peregrine Fans, there are two connections to your favorite bird.

  • Did you know that peregrines are closely related to parrots and not to hawks?  Click here to learn more.
  • And on the subject of names, how do peregrines get them?  Here’s the story.

 

(video from Cornell Lab of Ornithology)

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Apr 18 2014

Let Them Eat Eggs

This week’s weather was like a yo-yo — summer last weekend, winter mid-week, spring today.  The cold was annoying to us but potentially fatal to purple martins who migrated from Brazil and arrived in western Pennsylvania 2-3 weeks ago.

Purple martins feed exclusively on flying insects but when temperatures stay below 50F or it’s extremely windy, constantly raining, or dense fog, insects don’t fly.  After more than two days of this, purple martins weaken and starve.

Members of the Purple Martin Conservation Association remember the awful purple martin die-off when Hurricane Agnes lingered over western Pennsylvania in August 1972.  It took more than 30 years for purple martins to come back to our area.

In the past purple martin landlords felt helpless as they watched their colonies weaken and die. In the 1990′s Ed Donath trained his martins to eat non-traditional food but that required training time during good weather.  Then during a cold spell in April 2000 Ken Kostka and Andy Troyer figured out an emergency feeding strategy:  toss live crickets in the air.  At first the purple martins idly watched the airborne objects. Then they recognized the crickets as insects and made the connection “flying+insects”=food.  The martins feasted and the colony was saved.

The home video above by Larry Melcher shows how it’s done.  After the martins have learned to recognize the crickets as food, the bugs can be placed on a high tray on the colony and the martins will eat them even though they’re not flying.

Landlords have experimented with other foods.  Years ago Bird Man Mel in Missouri tossed live mealworms so his colony now recognizes mealworms as food and will eat them from the front porch trays (click here for his video).

On Wednesday birders Dick Nugent and Debbie Kalbfleisch visited a purple martin colony in Butler County where the landlord was feeding his colony scrambled eggs!  Here’s a video with the scrambled egg recipe.

Purple martin landlords love their birds.  They start feeding crickets, then let them eat eggs.

(videos from YouTube)

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Mar 22 2014

Dumpster Robins

Published by under Bird Behavior

The robins' dumpster and their favorite perch (photo by Kate St. John)

A few days ago I looked out my office window and saw two American robins perched on the dumpsters at Central Catholic High School.  As I watched, one dove into a dumpster and disappeared.  Soon it flew out of the flap opening on the left and the other robin dove in.

What is this?  I’m used to seeing crows, gulls and even house sparrows at dumpsters … but robins??

I tried to photograph the robins but always missed so I’ve had to settle for a snapshot of the dumpsters with a green symbol for the robins’ favorite pre-dive perch.

I wonder what attracted them into the dumpster.

I did not dive in to find out!

 

(photo by Kate St. John)

6 responses so far

Mar 13 2014

A Well Developed Sense Of Taste

European starling in Toulouse, France (photo from Wikimedia Commons, CC BY-SA 3.0)

This month the starling flocks will break up when the visitors head north and the locals begin to nest.  In the meantime this informational tidbit may be useful in controlling their roosting habits … or it might not.

On a random search about starlings I found this statement on Wild Birds Unlimited’s Chipper Woods website:  “Starlings have a well developed sense of taste, and are repelled by grape flavoring. Fogging with grape flavoring is an effective and environmentally safe method to discourage these birds from roosting.”

I know that starlings will eat just about anything, including grapes, so I wonder:  What is grape flavoring made of?  Do starlings detect something unnatural and dangerous in it that we cannot?

This starling, photographed in Toulouse, France, knows the answer.  You can tell by his look that he has a well developed sense of taste.

 

(photo from Wikimedia Commons, Creative Commons license. Click on the image to see the original.)

3 responses so far

Feb 25 2014

Bluebird Fight

Eastern bluebird fight (photo by Karen DeSantis)

We think of eastern bluebirds as gentle birds.  They seem to be poor fighters and often lose battles with house sparrows and starlings, so I was surprised to learn from Karen DeSantis that she witnessed two male eastern bluebirds in a long ferocious fight in late February a few years ago.

Karen described on PABIRDS how the fight began with chasing, then escalated into periodic knock downs and grim combat on the ground.  The males fluttered and rolled over a distance of about 30 feet while the female followed every move, twittering as she watched.  The birds were so oblivious that Karen was able to take photographs of the 15-minute battle.  Karen wrote, “It was the long duration of the fight that interested me the most.”

Though we might not realize it, these battles are consistent with bluebird behavior.

During the winter bluebirds flock in family groups and huddle together to stay warm.  In early spring their togetherness ends as the fathers eject their sons from the group before ‘Mom’ and ‘Dad’ nest again.

But the battle Karen witnessed was not a mild family squabble.  Its intensity indicates the guys were fighting over the lady.

Bluebirds are usually monogamous but about 20% of the young come from extra-pair copulations.  The males seem to know if their ladies’ eyes are wandering and guard their mates more closely if they’ve been messing around.  According to Birds of North America Online, “Experimental evaluations (Gowaty 1980) indicate male-male aggression most likely serves to protect threatened paternity. Males are aggressive to males usually in defense of paternity.”   These battles can be so intense that they end in the crippling or death of one of the birds.

Bluebirds may seem gentle but don’t mess with their mates!  Click on Karen’s photo above to watch a slideshow of the fight.

 

(photos by Karen DeSantis)

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