Archive for the 'Bird Anatomy' Category

Mar 16 2017

The Third Eyelid

Published by under Bird Anatomy

Great horned owl blinking its thrid eyelid (photo by Chuck Tague)

Great horned owl blinking its thrid eyelid (photo by Chuck Tague)

Did you know that birds have three eyelids?

Did you know they can see through the third eyelid, at least a little, because it’s transparent or translucent?

Read more about this fascinating and useful part of bird anatomy in this vintage article from 2010:

Anatomy: Nictitating Membrane

 

(photo by Chuck Tague)

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Jan 19 2017

Birds Wearing Black-n-Gold

Black and yellow birds who flock together in Western Panama (photo composite)

Black and yellow birds who flock together in Western Panama (photo composite)

On Throw Back Thursday:

These birds are wearing black-n-gold!

Just before the Steelers AFC Championship game in 2011 I explained why these black and yellow species tend to flock together.

This Sunday the Steelers are again in the AFC Championship.  What better time to revisit birds wearing black-n-gold.  Read on!

Wearing Black-n-Gold!

 

(composite photo credits, top left to right, then bottom left to right:
1. Slate-throated Whitestart: Corey Finger on 10000birds.com
2. Sooty-capped Bush Tanager: Wikipedia
3. Yellow-thighed Finch: Wikimedia Commons
4. Collared Whitestart: Jan Axel on janbirdingblog.blogspot.com
5. Silver-throated Tanager: Kent Fiala’s Website
6. Yellow-throated Brush Finch: Atrevido1 at Solo Aves on Flickr
)

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Dec 22 2016

Inside The Hollow Bones

Published by under Bird Anatomy

Hollow bone (photo from Henderson State Univ Nature Trivia by Renn Tumlison)

Hollow bone (photo from Henderson State Univ Nature Trivia by Renn Tumlison)

 

On Throw Back Thursday:

Six years ago I ran a series on bird anatomy.  Here’s a refresher course on bird bones, the strong, hollow, lightweight structures that allow them to fly.

Anatomy: Hollow Bones

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Dec 15 2016

What Limits the Size of Flying Birds?

Published by under Bird Anatomy

Wandering albatross (photo by JJ Harrison via Wikimedia Commons)

Wandering albatross (photo by J J Harrison via Wikimedia Commons)

On Throw Back Thursday:

Some mammals are as big as whales and elephants.  Why are there no enormous birds?

Find out why in this 2009 article:

What Limits the Size of Birds?

 

(photo by JJ Harrison via Wikimedia Commons)

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Dec 07 2016

How Birds Keep The Arctic Cool

Little auks (Alle alle) at Svalbard breeding colony (photo from Wikimedia Commons)

Little auks (Alle alle) at Svalbard breeding colony (photo from Wikimedia Commons)

Here’s amazing news:  Seabird colonies help keep the Arctic cool.

Seabirds gather on Arctic islands to breed during the summer.  Thousands of them nest close together and produce a lot of guano (bird poop).

Atmospheric scientists studying the Arctic noticed summertime bursts of ammonia-based particulate.  These tiny particles cause clouds to form because they gather moisture as they move through the air.  The clouds reflect sunlight and keep the land and water cool.

Where does the ammonia come from?  It wafts off the guano at the seabird colonies.

These findings were published on 15 November 2016 in Nature Communications.   Read the summary here at Science Daily.

 

(photo of little auks, Alle alle, at breeding colony on Svalbard by Alastair Rae from London, UK via Wikimedia Commons. Click on the image to see the original)

 

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Dec 05 2016

A Serrated Tongue

A Canada goose challenges the photographer (photo by David Amamoto)

Canada goose challenges the photographer (photo by David Amamoto)

Canada geese challenge their enemies by honking and rushing forward with head low, mouth open and tongue raised.  Normally we humans don’t see this up close but a goose challenged David Amamoto and revealed its amazing tongue to the camera.

Since Canada geese don’t have hands, their mouths are equipped with the tools they need for plucking grasses, sedges, grains and berries on land and in the water.

Their bills are serrated for cutting stems and threshing grain.  Their tongues have serrated edges for sieving water from each mouthful of underwater food.  The tongue’s crosswise bumps help grip the vegetation.

Food doesn’t get away from this serrated tongue.

Fortunately David escaped without being nipped.

 

(photo by David Amamoto)

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Nov 10 2016

Fallout

Evidence that crows roosted here (photo by Kate St.John)

Evidence that the crows roosted here (photo by Kate St.John)

As I mentioned on Monday, thousands of crows are back in Oakland roosting near the University of Pittsburgh.  Though the flock is spectacular they’ll soon be unwelcome.

If your neighborhood hosts a crow roost you know about the unpleasant debris left behind by these overnight visitors.  Everything is dotted with bird poop.  The sidewalks are slippery in the morning and the air smells “bird-y.”  This fallout is the #1 reason why crow roosts aren’t welcome near us.

When people have had enough, the crows must go.  The best way to move them is by persistent audio harassment.

In November 2013 the crows caused trouble night after night near the University of Pittsburgh Student Union so Maintenance set up a loud speaker that played bird distress calls and peregrine attack sounds over and over.  In five nights the crows were gone.

I have a theory that my favorite bird helped move them.  Read why at:

The Crows Moved

 

p.s. If the crows persist near Pitt, my hunch is that crow-scare tactics will begin by November 15.

(photo by Kate St. John)

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Oct 12 2016

As High As A Jet

Published by under Bird Anatomy

View from a jet crossing the Himalayas (photo by David Jones)

View from a jet crossing the Himalayas (photo by David C. Jones, Creative Commons license via Flickr)

Jet airplanes cruise at 30,000 to 40,000 feet.  Did you know that birds can fly at the low end of that range?

Birds’ respiratory systems are so efficient that they can pull oxygen out of very thin air.  We know this because they migrate over the Himalayas.

Common cranes (Grus grus) are widespread across Europe and Asia, nesting from Norway to Siberia and wintering from Africa to southern China.  Those that nest in eastern Kazakhstan and northwestern China fly over the Himalayas to spend the winter in India.  They’ve been clocked at 33,000 feet!

Common cranes in flight (photo by Ján Svetlík)

Common cranes in flight (photo by Ján Svetlík, Creative Commons license via Flickr)

 

Bar-headed geese (Anser indicus) nest in the Tibetan highlands and spend the winter in the lowlands of India. The shortest route from Tibet to the sea is to fly directly over the Himalayas, and so they do.  They’ve been recorded at 29,600 feet and seen flying over Mount Everest!  This video shows how they do it.

 

And even mallards, the ubiquitous ducks that eat bread at the boat launch, were seen migrating at 21,000 feet over Nevada.

 

Birds don’t need oxygen masks at those high altitudes.  They just fly by.

 

(photo credits: All photos are Creative Commons licensed via Flickr. Click on each image to see its original:
View from a jet over the Himalayas by David C. Jones on Flickr
Common cranes in flight by Ján Svetlík on Flickr
Mallards in flight by Ken Slade on Flickr
Video from FantasticAnimal on YouTube
)

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Oct 06 2016

How A Bird Can See From Every Angle

Published by under Bird Anatomy

American Goldfinch (photo by Sam Leinhardt)

American Goldfinch (photo by Sam Leinhardt)

On Throw Back Thursday, a vintage article from 2009:

Small birds have to watch out for danger all the time to avoid being eaten by hawks and cats. But how do they see from every angle?

This goldfinch has …

Eyes in the back of her head

 

(photo by Sam Leinhardt)

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Oct 05 2016

Why Canaries In The Coal Mine?

Published by under Bird Anatomy

Station Officer John Scott holding a canary cage used in mines rescue training at Cannock Chase, UK (Image courtesy of the Museum of Cannock Chase. Copyright unknown)

John Scott holding a canary cage used in coal mines rescue training at Cannock Chase, UK (Image courtesy of the Museum of Cannock Chase. Copyright unknown.)

Today, a bird anatomy lesson.

You’ve probably heard the phrase “the canary in the coal mine” and know it refers to advanced warning of a danger.  In the centuries before air quality instruments, miners carried canaries in cages into the mines to detect carbon monoxide and methane before they reached dangerous levels for humans.

Why did we use birds to detect bad air? Why not some other small animal?

Birds are uniquely equipped to detect (and succumb!) to bad air because their respiratory systems are so efficient.  Here’s why.

Our lungs suck in air, exchange oxygen for carbon dioxide, and push it out.  This is slightly inefficient because some air remains in our lungs after we exhale.  If you’ve ever had “the wind knocked out of you” you know it feels awful to lose that residual air.

Action of the diaphragm (animation from BIO 378, Prof. Gary Ritchison, Eastern Kentucky University)

Human lungs and diaphragm (animation from BIO 378, Prof. Gary Ritchison, Eastern Kentucky University)

 

Birds’ lungs don’t expand and contract; they only perform the oxygen-CO2 exchange.  Instead birds have 7 to 12 air sacs that act like bellows, moving air in and out of the lungs and the body.  The air sacs (pink below) move air in only one direction through the lungs (dark blue below), pushing all of one breath out when the next one comes in.  No residual air!

Bird respiratory system, airsacs highlighted (image from Wikimedia Commons)

Bird respiratory system, air sacs highlighted (image from Wikimedia Commons)

Because the air sacs perform different functions, each air molecule takes 4 steps to pass through the bird’s body –> two in/out breaths.

1st Breath, Air molecule enters the bird.

1. Inhalation:  Molecule is sucked into the body by the posterior (back of the bird) air sacs
2. Exhalation: Posterior air sac pushes molecule into bird’s lungs

2nd Breath, Air molecule leaves the bird.

3. Inhalation:  Molecule is pulled out of the bird’s lungs by the anterior (front) air sacs
4. Exhalation: Anterior air sac pushes molecule out of the bird!

In this way, birds have more time to absorb oxygen from each breath and their bodies notice airborne poisons sooner than mammals do.

To put it all together, here’s a four and a half minute video that shows how it works.

 

One more amazing feat:  The thin walls of birds’ air sacs can extend into the hollow bones of their wings and legs.  They have extra places to store air!

 

(photo credits: Click on each image to see its original in context.
*Station Officer John Scott with canary cage used in coal mines rescue training at Cannock Chase, UK. Image courtesy of the Museum of Cannock Chase. Copyright unknown.
*Human lungs and diaphragm. Image linked from Bio 378, Lecture 10, Prof. Gary Ritchison, Eastern Kentucky University
*Bird respiratory system diagram from Wikimedia Commons.
*Video of bird respiration by Ammt Bio on YouTube
)

 

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