Category Archives: Bird Anatomy

Feathers Wear Out

Recently molted feathers of Black-legged Kittiwake (photo by Jymm in public domain on Wikimedia)
Recently molted feathers of a black-legged kittiwake (photo by Jymm in public domain on Wikimedia)

On Throw Back Thursday:

Many birds molt during summer's "down time" between raising their young and fall migration.  At this point their feathers have worn out.

However (news to me!) female peregrine falcons choose a different time of year.  They begin to molt during incubation, a convenient time to do it because they're temporarily sedentary and their mates supply their food.  That's why we sometimes see a peregrine primary feather in the nest box.  Who knew!

Read more about feather wear and molting in this vintage article: Feathers Wear Out

 

(photo from Wikimedia, in the public domain.  Click on the photo to see the original)

Special Equipment For Warming Eggs

Dori rolls the eggs just before she resumes incubation (photo from the National Aviary falconcam at Gulf Tower)
Dori rolls the eggs before she resumes incubation (photo from the National Aviary falconcam at Gulf Tower)

To become baby birds, eggs must be warmed to around 98.6 °F and remain at that temperature while the embryos develop.  Adult birds that incubate(*) have special equipment to accomplish this:  bare skin on the belly called a brood patch.

We don't usually see the brood patch because surrounding feathers close over it to keep the adult warm.  When a bird comes back to its nest to incubate, it opens its belly feathers to lay its bare skin against the eggs.  You may have seen peregrines open their belly feathers by standing over the eggs and rocking side to side.

Click on the link below to see an American kestrel's brood patch and learn about this important part of bird anatomy, the Brood Patch.

 

(*) p.s. In eagles and peregrines, both sexes incubate so both have brood patches but this isn't the case with all birds.  In many duck species, only the female incubates so the males don't have brood patches.

 

(photo from the National Aviary falconcam at Gulf Tower)

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
)

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)

 

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)

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)

As High As A Jet

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.

Mallards in flight (photo by Ken Slade, Creative Commons license via Flickr)
Mallards in flight (photo by Ken Slade, Creative Commons license via Flickr)

 

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
)