Archive for November, 2013

Nov 20 2013

The Branches Add Up

Published by under Trees

Bare tree at sunset, Philadelphia (photo from Wikimedia Commons)

Now that the trees are bare you can do a little math on their branches.

Did you know that if you start at the trunk, gathering together all the branches and squeezing them tightly all the way to the top, the bundled branches will be the same circumference as the tree trunk?  The tree would be one big cylinder, all the same thickness as the trunk.

This principle is Da Vinci’s Rule of Trees. More than 500 years ago Leonardo wrote: “All the branches of a tree at every stage of its height when put together are equal in thickness to the trunk.”

Intuitively we can guess this is true, but the rule is very impractical to prove by hand.  A small tree could be squeezed – and sacrificed by the experiment – but a larger tree has to be measured and calculated.  As physicist Christophe Eloy of University of Provence said, “If you’re looking at big trees, there’s thousands of branches, and it takes a lot of undergrads to measure it.”

Two years ago Christophe Eloy proved Da Vinci’s Rule of Trees and the reason why it occurs by designing intricately branched trees on a computer and putting them through a virtual wind tunnel.

The designs, like the trees, were branching fractals repeated over and over.  With each design Eloy varied the thickness of the branches and subjected them to virtual wind forces that broke them.  Invariably when he found a combination that withstood the wind, it matched Da Vinci’s rule.  This not only proved the rule but showed that wind is a reason for the rule’s existence.  His findings were published in the journal Physical Review Letters in 2011.

Of course Eloy’s proof involved math and physics.  Here’s his diagram of the fractal thickness and one of his computed trees.

Tree branches and trunks follow Da Vinci's Rule (image courtesy Christophe Eloy, University of Provence)

(Image Courtesy Christophe Eloy | University of Provence)

 

But don’t take my word for it.  Read more about Christophe Eloy’s study and Da Vinci’s Rule of Trees at this link in Inside Science.

 

(photo of a bare tree at sunset from Wikimedia Commons.  Tree diagram courtesy Christophe Eloy, University of Provence linked from Inside Science.  Click on each image to see its original.)

2 responses so far

Nov 19 2013

An Eagle Like A Crane

In Africa there’s a bird of prey with legs so long he looks like a crane.

Though the secretary bird (Sagittarius serpentarius) can fly he prefers to walk as he browses for food in the underbrush.  His legs are so long he has to crouch to get his beak to the ground.

A scorpion is a snack, a mongoose is a meal.  Secretary birds even eat poisonous snakes, adders and cobras, which they stun and kill by stomping with their feet.

Perhaps that’s why these birds are so tall.  Their bodies are out of reach of their dangerous prey.

I love to watch them walk:  crane-like eagles with black knee-pants.

 

(video from WildlifeVideoChannel on YouTube)

One response so far

Nov 18 2013

Not Born Like This

Black Skimmer (photo by Steve Gosser)

Speaking of pied shorebirds as I did yesterday …  when I see American oystercatchers I’m reminded of black skimmers (Rynchops niger).  Both have bold black-and-white plumage and long beaks but their differences are striking.

Unlike oystercatchers, skimmers have very short orange legs and a beak whose mandibles are two different lengths.  They use their long lower mandible — 2-3 cm longer than the upper — to skim food from the ocean’s surface in flight.  Click here to see.

Black skimmers aren’t born like this.  At hatching their beaks are normal but by the time they fledge four weeks later their lower mandibles have grown 1 cm longer than the uppers, halfway to this striking adult appearance.

One more amazing beak fact:  Black skimmers’ beaks look fat from the side but if you see them straight on they are knife-thin like this.

The better to skim with, my dear.

 

(photo by Steve Gosser)

No responses yet

Nov 17 2013

Pied

Published by under Water and Shore

American oystercatcher (photo by Gintaras Baltusis)

American oystercatchers look so unusual that it’s hard to mistake them for anything else:  big orange bill, yellow red-rimmed eyes, bold black, white and brown pattern, and thick beige legs.

Gintaras Baltusis found these two at Breezy Point, New York in late September.   Look closely and you can see they aren’t the same age.

The juvenile (below) has the same feather pattern but doesn’t have yellow eyes and his bill is still half black.

American oystercatcher (photo by Gintaras Baltusis)

 

Before Mark Catesby renamed them in 1731 American oystercatchers (Haematopus palliatus) were called Sea Pies because of their pied plumage.  Fortunately their new name describes what they eat and cannot be confused with what we eat, a casserole called a Sea Pie.

Can you think of other pie-named birds?  I know of three in North America.

 

(photos by Gintaras Baltusis)

2 responses so far

Nov 16 2013

Two Free Bird Events Next Week

Published by under Books & Events

Here are two free bird events coming up next week in Pittsburgh.

Guam rail at the National Aviary (photo from Wikimedia Commons)Monday November 18, 4:30pm, Guam Rail Reintroduction Presentation at the National Aviary

Laura Barnhart Duenas, manager of the Guam Rail and Micronesian Kingfisher captive breeding program at Guam’s Division of Aquatic and Wildlife Resources, will present a lecture on the successful bird conservation work she’s doing to reintroduce the Guam rail and other birds wiped out by the invasive brown tree snake.

The flightless Guam rail became extinct in the wild in the late 1980’s but has been bred in captivity and returned to small snake-free islands in the Mariana archipelago (Guam’s island zone).  The National Aviary has bred Guam rails since 1984, hatched 57 chicks and returned 23 of them to Guam.

Doors open at 4:00 p.m. Click here for more information. Click here for directions.

.

.

Flamingo folio print by John James Audubon (courtesy University of Pittsburgh)

Friday, November 22, 9:00am to 4:45pm, Annual Audubon Day at the University of Pittsburgh

Next Friday the University of Pittsburgh will host their annual Audubon Day at Hillman Library.  More than two dozen original John James Audubon prints will be on display in the Special Collections Reading Room, Room 363.

In addition, from 10:00am to noon, Joel Oppenheimer, one of the world’s foremost Audubon experts, will deliver a presentation titled “Audubon’s Art and the Published Editions from the Nineteenth Century to the Present” in the Amy Knapp Room on Hillman’s ground floor.

For more information including the day’s agenda, click here.

.

.

 

(photo of Guam rail at the National Aviary from Wikimedia Commons; click on the image to see the original. Flamingo print by John James Audubon, courtesy of University of Pittsburgh)

No responses yet

Nov 15 2013

The Crows Moved

Since late October, Pittsburgh’s winter crow flock has been big and brash in Oakland.  At dusk they flood the sky, gathering on roofs and treetops to choose a place to sleep.  Last week they roosted in the trees around Pitt’s Student Union and the Cathedral of Learning.  This got them into big trouble!

Every night pedestrians dodged the “rain” from trees filled with crows and every morning the sidewalks were a slippery crow-poop mess.  The crows had to go.  But how to convince them?

Last weekend Pitt positioned a loudspeaker on the low roof of the Student Union and played very loud bird distress calls over and over all night. They ran it for five nights, Friday through Tuesday, Nov 8-12.

Most people didn’t know it was a recording.  In the dark it sounded like birds fighting and dying:  a robin in awful distress, an unidentified bird screaming and a peregrine kakking.

Late Saturday night Jason Carson recorded the video above and tweeted me with the question: “What is this? Are the peregrines fighting?”

Initially I was fooled and thought it was real, though it didn’t make sense.  Any bird suffering that much would have died after the first assault and the noise would not repeat.  Then Pat Szczepanski told me she heard it Sunday night at 6pm and it dawned on me.  Duh! It’s a recording.

Usually crows are not impressed by bird distress recordings.  They are way too smart to be fooled for long.  Sometimes the only thing that will move them are bird-scare firecrackers like the ones they use at Penn State (click here for videos of Penn State’s “crow wars”).

Why were a few nights of noise enough to move Pittsburgh’s crows away from the Cathedral of Learning?  I have a theory and I think it’s pretty good.

Crows are afraid of peregrines but they’re more afraid of great horned owls.  They know Dorothy and E2 live at the Cathedral of Learning and they know peregrines hate great horned owls so they probably figured “The enemy of my enemy is my friend” and they chose to roost at Pitt.

But last weekend there was an awful ruckus and the sound of peregrines defending their home.  “Oh my gosh!” thought the crows, “The owl must be here!  I hear the peregrines attacking it!”

In the dark Dorothy and E2 swooped low to investigate the noise.   “Oh no!” said the crows, “The peregrines are here!  Fly away!”

The crows didn’t move far but they moved far enough.  By Monday evening they were avoiding the trees on campus and roosting instead on the roof of Soldiers and Sailors Hall.   Just far enough to avoid the owl and the peregrines.  Just far enough that Pitt is happy.  Just far enough that the noise has ceased and Dorothy and E2 can get a good night’s sleep.

Without real live peregrines at Pitt, the crows would not have been fooled.

 

(video from Jason Carson on YouTube)

10 responses so far

Nov 14 2013

Positive Parroting

African Gray Parrot (photo courtesy Joe Brunette/©2013 THIRTEEN Productions LLC))

If you watched Parrot Confidential on PBS NATURE last night you know that people fall in love with parrots’ charm and beauty but often adopt them with almost no information on their needs.

Unfortunately there aren’t many ways to learn about parrots except by trial and error.  This can lead to huge frustration and the birds’ surrender to an uncertain future.

If you already own a parrot or are contemplating a purchase or rescue, where can you turn?

Parrot Confidential’s website provides a list of conservation, sanctuary and advocacy resources across the U.S.   Even better, if you live in Pittsburgh you can get a hands-on education at the National Aviary’s Positive Parroting classes.

Twice a year Dr. Pilar Fish (head avian veterinarian) and Cathy Schlott (manager of bird training) conduct three two-hour classes that provide practical resources and information to lower frustration and keep the bird united with the owner.

I spoke with Dr. Pilar Fish about the classes.  She’s a life-long parrot owner, former rescuer and parrot advocate.  In fact she became a bird veterinarian because of her love for parrots. She can tell you that owning a parrot is a totally absorbing hobby, a lifelong relationship and a lifestyle-changing commitment.  As she says, “I’ve been there. I want to be a resource.”

Most people don’t realize that parrots are advanced, complex animals.  They have the intelligence and problem-solving skills of toddlers (African Grays are like 6-year-olds!) but the emotional maturity of a 2-year-old.  Imagine a child in its “terrible twos” confined to a small space with a single toy and the same food day after day.  Of course he’ll have tantrums!

In class you’ll learn how to adjust for the bird’s natural behavior.  What do these birds do all day in the wild?  If you provide your parrot with his natural routine and toys to occupy his mind he’ll be much happier.  So will you.  In class you’ll get a “cookbook” of habitats, schedules and tips and you’ll make toys to occupy your parrot and enrich his life.

The second part of Positive Parroting is about problem solving.  Cathy Schlott teaches how to train your bird in a positive way, reward good behavior and deal with behavioral issues.  She gives live demonstrations using the Aviary’s own parrots, some of whom are former pets.

Fall classes have already begun.  The first class, The Healthy Happy Parrot, was held on October 26.  Still to come are:

  • Pet Bird Enrichment, this Saturday November 16, 2013, 10:00 am—12:00 pm. (enhance natural behaviors)
  • Training Your Pet Bird, Saturday December 7, 2013, 10:00 am—12:00 pm (problem solving)

Click on this link for information on Positive Parroting.  Education is good!

 

p.s.  If you haven’t seen Parrot Confidential yet, watch WQED’s rebroadcast at 5:00am tomorrow, Friday November 15.  The online broadcast is available at Parrot Confidential’s website.

 

(photo of African Gray Parrot courtesy Joe Brunette/©2013 THIRTEEN Productions LLC)

2 responses so far

Nov 13 2013

Give Back, Get Back

Chidham Point, West Sussex, UK (photo from Wikimedia Commons)

Breach an earthwork like the one above, give back land to the sea, and you’ll get fewer floods.

After Hurricanes Katrina and Sandy, U.S. emergency managers and town planners are discussing giving back land to the ocean as a way to protect still-viable coastal communities.  It’s a concept called “managed retreat,” a name that conjures loss and sometimes sparks defiance in those who live at the ocean’s door.

In the U.K. they’ve recently returned more than 450 acres to the sea by breaching an earthwork just five miles from this one at Chidham Point.  The locals are excited about it.  They expect the resulting salt marsh to increase tourism.  Here’s how:

At Medmerry on the south coast of England, shingle(*) sea walls were supposed to protect towns and undeveloped land but in recent years have proved inadequate.  Stronger storms and higher tides frequently flooded the low-lying communities, especially the caravan (campers) vacation parks.  Some sections of Selsey and Bracklesham Bay are below sea level.  It wasn’t working.

In 2011 the U.K.’s Environment Agency began a managed retreat project in West Sussex.  They built four miles of new sea walls up to a mile inland around the developed areas.  They also built drainage ditches and ponds, two parking lots for visitors, and 10km of bicycle paths and horse trails.  Then they breached the earthworks and gave land back to the sea.  The resulting salt marsh buffers the ocean’s rage.

It’s also great for wildlife.  Even while construction was underway migrating water birds stopped by to visit the growing new salt marsh.  Bird watching improved immediately and is expected to get even better in the months and years ahead.  The new salt marsh will be a birding tourist destination.

Give back to the sea and get back safety and tourism.  Compromise with Mother Nature is good.

Read more about this project and see a video here at the BBC News.

 

(photo of dike at Chidham Point, West Sussex, UK, located about 5 miles from Medmerry)

(*) The British word “shingle” means the sand, pebbles, cobbles and shell-pieces that make up the beach.

2 responses so far

Nov 12 2013

Sparrow Time

Published by under Migration,Songbirds

Fox sparrow and white-throated sparrow (photo by Steve Gosser)

It’s not news that migrating sparrows are back in town but it’s always news to see a fox sparrow in any setting.

Steve Gosser photographed this one (top) with another migrant, a white-throated sparrow, at Harrison Hills Park last week.

Some sparrows come to western Pennsylvania in the fall and stay all winter, including dark-eyed juncoes, American tree sparrows, and the white-throated sparrow shown above.

But fox sparrows are few and far between and right now they’re just passing through, headed for the southern U.S.

If you don’t see one before Thanksgiving you’ll probably have to wait until March to catch them on their return trip back north.

I’ve been looking, but so far no luck.

 

(photo by Steve Gosser)

No responses yet

Nov 11 2013

Lawn Sprinkler In The Sky

Published by under Weather & Sky

Asteroid P/2013 P5 as seen on two days in September 2013 from the Hubble Space Telescope (photos courtesy of NASA)

Back in September an amazing asteroid flew by in outer space.

It first appeared as a fuzzy dot, seen by a PanSTARRS Survey telescope in Hawaii.  Wondering what it was, astronomers directed the Hubble Space Telescope to take a look.  Boy, were they surprised.  It has six tails!

This is not a normal asteroid.  Asteroids are very tiny planets and — until now — they don’t have tails.  This one is only 700 feet across and is traveling around the sun in the asteroid belt between Mars and Jupiter.  Like it’s traveling companions in the Flora asteroid family, its probably a chunk left over from a planetary collision.

So why does it have tails?  Comets have tails because they are made of ice, dust and small rocks.  When they get near the sun the ice evaporates, causing a long streamer of debris.  But this asteroid has no ice.  It must be streaming dust.  Lots of it.

Scientists named it P/2013 P5 and ran its behavior through modelling software at the Max Planck Institute for Solar System Research.  The model showed this asteroid is spinning so fast that anything loose on the surface (dust) is traveling toward its equator.  There it accumulates and episodically escapes the asteroid’s weak gravity, arcing into outer space. Yow!  Six tails!

Why is it spinning so fast?  Scientists theorize that the pressure of sunlight could have pushed P/2013 P5 into a tail spin.

Photos, above, from the Hubble Space Telescope show it spinning like a lawn sprinkler in the sky.

 

Read more here at NASA’s Hubble website.

 

(images of Asteroid P/2013 P5 from the Hubble Space Telescope, courtesy of NASA)

No responses yet

« Prev - Next »

Bird Stories from OnQ