Archive for the 'Bird Behavior' Category

Feb 11 2015

Crows Exonorated!

In some cultures and for some people, crows have a bad reputation. Their black feathers and eerily intelligent behavior have linked them with bad luck and death.   Even those of us who like crows are upset when we see them take birds’ eggs and nestlings.  Our distaste for this extends to other members of the corvid family as well.

Some game and conservation organizations kill corvids believing this will help the small birds that corvids prey upon.  Does it?  A recent study published in Ibis says “No.”

The Institute of Research in Game Resources (IREC) studied 326 interactions between corvids and their prey in Europe and North America.  They monitored 67 prey bird species including passerines and game birds.

When researchers removed all predators from the study areas the prey-bird populations increased but when they removed only the corvids there wasn’t much change.  In fact, some prey populations suffered in the absence of crows!

Crows had an impact on reproductive success but this didn’t make much difference to the species’ populations.  Study author Beatriz Arroyo said: “In 81% of cases studied, corvids did not present a discernible impact on their potential prey. Furthermore, in 6% of cases, some apparently beneficial relationships were even observed.”

So is it good conservation practice to kill corvids?  “This method of managing populations is frequently ineffective and unnecessary,” says Arroyo.

Crows are exonerated!

Read more about the study here in Science Daily.

 

p.s. As you can see in the video, crows just want to have fun.  😉

(video of a hooded crow on YouTube.  Hooded crows are native to Europe.)

 

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Feb 05 2015

TBT: Cardinals See Red

Northern cardinals feeding together in the snow (photo by Marcy Cunkelman)

Throw Back Thursday (TBT):

Winter is more than halfway over.  We turned the corner on Groundhog Day.

As spring sunlight increases, birds’ hormones trigger courtship and territorial behavior.

Northern cardinals feed peacefully together during the winter but soon the males won’t tolerate each other.  Click here to read about their spring behavior in this blog post from 2008:  Cardinals See Red.

 

(photo by Marcy Cunkelman)

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Feb 03 2015

In The Corvid Niche

Pearly-eyed thrasher (photo from Wikimedia Commons)
As I mentioned yesterday, there are no corvids in the Virgin Islands.  In fact there are no crows, jays or ravens in Puerto Rico and the Lesser Antilles but there is a bird who fills their niche.

The pearly-eyed thrasher is the size and shape of a normal thrasher but he’s not a skulker like the brown and Crissal thrashers of North America.  Instead he acts like a blue jay: bold, brash, adaptable and inquisitive.  Conspicuous in flight, he lands with a thud and hop-turns on his perch.  He calls in public and his youngsters beg loudly.

Like corvids, the pearly-eyed thrasher is omnivorous and opportunistic.  He eats fruit, insects and vertebrates including eggs, nestlings, lizards, land crabs and tree frogs.  He’s even earned a reputation for “stealing” because he’s willing to wait and swoop in when humans turn their backs at meal times.  The thrasher below was photographed at a restaurant in the British Virgin Islands “just waiting for the waitress to leave the area so he could enjoy the remains of breakfast left on the tables.”

Pearly-eyed thrasher (from Wikimedia Commons)

And like any corvid, he’s willing to peck an animal he thinks he can kill.

Last Friday during the Francis Bay bird walk our National Park Service guide, Laurel, looked around a corner and suddenly called, “Thrashie! Thrashie! He’s pecking a baby iguana!”  She rushed to the iguana’s rescue and the thrasher flew up to watch his prey.

Laurel showed us the green iguana which was about the same size as the thrasher.

Baby iguana just rescued from a pearly-eyed thrasher attack (photo by Kate St. John)

Here the iguana is a blur as it tries to get out of her hand.

Baby iguana, moving in hand (photo by Kate St. John)

Laurel hid the iguana among green leaves and we moved on to watch the black-necked stilts, leaving the pearly-eyed thrasher behind.

Who knows what happened next.

 

(Pearly-eyed thraser photos from Wikimedia Commons. Click on the images to see the originals.
Iguana photos by Kate St. John
)

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Jan 12 2015

That’s Close Enough

Published by under Bird Behavior

Emu closeup (photo from Wikimedia Commons)

These pictures from Wikimedia Commons tell a story.

Christian Jansky was capturing some nice closeups of an emu (Dromaius novaehollandiae) at the zoo in Stadt Haag, Austria while the bird stood patiently.

Suddenly the emu had had enough.  “Don’t come so close!”  He made a move to bite the camera.

Emu closeup with its mouth open (photo from Wikimedia Commons)

Notice how the nictitating membranes are now covering the bird’s eyes so they don’t get hurt while he attacks.

I wonder what happened next.

 

(photos from Wikimedia Commons.  Click on the images to see the originals.)

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Jan 11 2015

I’m Gonna Get You!

Raven chases bald eagle chasing osprey (photo from Wikimedia Commons)

This photo is tiny but it shows the pecking order in the sky.

The bird on the left is an osprey, the middle one’s a bald eagle, the right one is a raven.  Click here or on the photo to see a full size image with a better view of the birds.

The bald eagle wants the osprey’s fish. The raven’s harassing the bald eagle. It’s unusual that all three lined up in one big chase.

“I’m gonna get you!”

 

(photo by Ciar via Wikimedia Commons.  Click here to see the original photo with documentation.)

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Jan 08 2015

TBT: Coping With Cold

Published by under Bird Behavior

Red-bellied woodpecker at the feeder (photo by Marcy Cunkelman)

On Throw Back Thursday (TBT) …

Brrrr!  It’s zero degrees F (-18 C) at 8:00am this morning with a wind chill of -16 F (-27 C).  Bundle up!

What about the birds?  How do they cope with cold?

In January 2008 I wrote about their #1 strategy –>   Coping With Cold: Food.

In the old article you’ll notice it wasn’t even as cold on January 4, 2008 as it is this morning.  Last winter’s Polar Vortex changed my definition of “cold.”

 

(photo by Marcy Cunkelman)

 

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Jan 03 2015

Early Singer

Carolina wren (photo by Gregory Diskin)

Speaking of First Bird of the Year, who’s the first bird to sing in your neighborhood?  Have you heard any singing yet?

In Pittsburgh most birds stop singing in mid summer, though a few late-nesting residents keep it up until autumn.  They’ve been silent for months now.

A few hardy souls sing in January.  The First Singer in my backyard is usually a Carolina wren who pipes up just before dawn.  On a good morning his voice echoes off the hills and prompts competing wrens to respond.

… But this is not a good morning.  We have freezing rain today. :(

Even on a good day he’s silent within 15 minutes.  I’ll know it’s spring when he sings all day.

 

(photo by Gregory Diskin)

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Dec 23 2014

A Game Of Chicken

Published by under Bird Behavior

House sparrows at the Walmart parking lot (photo by Sage via Flickr, Creative Commons license)

Ever since my husband was hit by a car last month I am very wary of crossing the street.  I watch and wait.  I flinch when I see others crossing unsafely.

Last week while waiting to cross Forbes Avenue at Craig Street I saw a flock of house sparrows playing in traffic.  When vehicles stopped for the red light the sparrows perched on the road underneath them.  As the cars began to drive away the birds flew out quickly.  I could barely stand to watch but I was mesmerized.

Apparently the flock craved more excitement.  They perched at a parking lot while traffic was moving fast but as soon as it slowed they zoomed low across the street at bumper height right in front oncoming vehicles!  They were going to get hit!  I couldn’t keep from shouting, “Fly fast, little birds!”

They made it.

Then they did it again.  They’re nuts!

The house sparrows were playing a game of Chicken.

 

(photo of house sparrows waiting in the Walmart parking lot by Sage on Flickr, Creative Commons license. Are they waiting to play Chicken?  Click on the image to see the original)

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Dec 16 2014

Socially Isolated? Age Faster

African grey parrot (photo by Keith Allison from Wikimedia Commons)

Early this month I wrote how lobsters don’t age because they have telomerase that repairs the DNA sequences at the ends of their chromosomes (telomeres).   Most adult organisms don’t have that advantage so every time our cells divide our telomeres get shorter.  This ages our cells and ages us.

African grey parrots are highly social creatures who are often stressed when they live alone.  It turns out that loneliness affects their telomeres.

In a study published last spring in PLOS ONE, scientists at the University of Veterinary Medicine at Vienna, Austria examined blood samples from captive African grey parrots and compared the telomeres of parrots who lived alone versus those who lived with a companion parrot. (*)

Despite being the same age, solo African grey parrots had noticeably shorter telomeres than those who lived with friends.  The solo parrots aged faster than their peers.

Not only did the study illuminate the sadness of single parrots but it suggests that “telomeres may provide a biomarker for assessing exposure to social stress.”

Read more here in Science Daily.

Humans are social creatures, too.  Doctors and nurses know that isolated humans don’t heal as fast or live as long, so when you’re sick it helps to have the care of those who love you … which leads me to an update on my husband’s recovery (see this blog post for news of his accident).

Today it’s been three weeks since Rick was hit by a car in a crosswalk.  He’s making progress though there are setbacks, such as the operation to fix his broken nose.  Fortunately his friends and relatives have rallied to help him (and me).  Rick is a very social creature — more social than I am — so calls and visits from his sister and friends have raised his spirits.

For now my life is circumscribed by his needs and appointments.  I miss birding and hiking alone (I’m not as social as Rick) but I try to go outdoors every day because that’s what keeps me sane.

We are hoping for good long telomeres when this is over.  😉

 

(photo by Keith Allison from Wikimedia Commons.  Click on the image to see the original)

(*) The parrot news release notes that in Austria it’s illegal to keep a parrot in isolation from other parrots, though some people do.

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Dec 15 2014

Can’t Tell Their Sex By Their Color

White-throated sparrow, white-striped color morph (photo from Wikimedia Commons, Creative Commons license)

White-throated sparrow, white-striped color morph (photo from Wikimedia Commons)

Many birds are sexually dimorphic — males are more colorful, the females are drab — but this isn’t true of white-throated sparrows.

White-throated sparrows come in two color morphs: white-striped shown above, tan-striped below.  The crisp white-striped birds aren’t always male, the plain tan-striped birds aren’t always female.  You can’t tell their sex by color.

White-throated sparrow, tan-striped color morph (photo by Henry McLin on Flickr, Creative Commons license)

White-throated sparrow, tan-striped color morph (photo by Henry McLin, Flickr Creative Commons license)

Here they are side-by-side: white-striped on left, tan-striped on right.  Notice that …

White-throated sparrows -- white-striped and tan-striped side-by-side (photos from Wikimedia Commons and Henry McLin, Creative Commons licenses)

  • Head stripes are black-and-white versus brown-and-tan
  • Lores are bright yellow versus dull yellow
  • Malar stripe is weak versus prominent
  • Breast is gray versus brown-and-tan
  • Breast is mostly clear versus very streaky

Not only do they look different but the white-striped birds are aggressive, philandering and don’t take much care of their kids while the tan-striped birds are gentle and very caring of their young.

You would think these differences would force one of the color morphs to disappear from the gene pool but it doesn’t.  The reason is surprising.

When it comes to picking mates, these birds always mix it up.  White-striped (aggressive) males mate with tan-striped (care-giving) females and the tan-striped (gentle) males mate with white-striped (philandering) females. Thus the color morphs and personalities persist.

Learn more about their amazing social behavior in this article by GrrlScientist in The Guardian, May 2011.

And when you see white-throated sparrows you’ll know you can’t tell their sex by their color but the drab ones are always good parents.

 

(photos: White morph white-throated sparrow from Wikimedia Commons, Creative Commons license.  Tan morph by Henry McLin on Flickr, Creative Commons license.  Click on each photo to see its original)

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