Fabulous Feathers

We learn at a young age that birds have feathers. Feathers help a bird to fly.  While I’m not about to refute that fact, it must be said that there is so much more to feathers that makes them truly fascinating.

First of all, there are seven different kinds of feathers.  There are wing feathers, tail feathers, contour feathers (which cover the bird’s body), semiplumes (slightly fluffy), down feathers (REALLY fluffy), filoplumes and bristles (long skinny whisker-like feathers).  Each different kind of feather serves a different kind of purpose.

Keeoo the Augur Buzzard displaying the overlapping pattern of wing feathers and the rudder-like tail feathers (photo: Gay Schroer)

Wing feathers help form the shape of the wing into an airfoil to gain lift, and tail feathers act as a rudder to help a bird steer.  Of course, this assumes that the bird in question can fly at all.  In some species, such as the ostrich, flight is not an option.  Oftentimes, when this is the case, the wing and tail feathers are not stiff and flat, but have evolved to become more ornate for use in territorial or courtship displays.

Another view of how Keeoo's wing feathers overlap (photo: Gay Schroer)

Contour feathers form an interlocking, overlapping pattern over the bird’s body.  This helps to streamline the bird…and keep it waterproof.  Thanks to the pattern of the contour feathers, only the waterproof tips are exposed, allowing water to bead up and roll right off of the bird.  This is especially important in waterfowl, which would otherwise be soaked and cold.

A Snowy Owl is a perfect example of the insulating properties of feathers--even the bottoms of their feet are feathered (photo: Gay Schroer)

Semiplumes and down feathers are located underneath the outer feathers, where their fluffy barbs act as insulation.  The delicate fluff on these soft feathers creates small pockets of air next to the bird’s body.  These pockets of air under the contour feathers help insulate and keep the bird warm as outside temperatures cool down.   Down feather coats and comforters keep us so warm the same way.

A White-faced Barbet (Photo: wikipedia)

Filoplumes and bristles hardly look like feathers at all.  They have no barbules branching out from the central part of the feather, also called the rachis, so they resemble whiskers more closely than feathers.  This is rather appropriate, since the purpose they serve is similar to that of whiskers.  Filoplumes, which have teeny-tiny barbules at the very tip of the feather, help to sense the position of the contour feathers; and bristles, which have almost no barbules at all, are often found on or around the bird’s face.  Bristles may act as whiskers but also likely serve to protect the bird’s eyes and face, much like our eyelashes.

So yes, birds have feathers.  One could leave it at that, but why on earth would you want to, when there is much more to be learned once you delve into the fascinating and fabulous world of feathers?

Submitted by World Bird Sanctuary Naturalist JoHanna Burton

Editors Note:  The World Bird Sanctuary, and the blog in particular, are sad to say farewell to Naturalist JoHanna Burton who is leaving us to move across the country  We wish her godspeed and know that with her strong work ethic she will do well in any future path she chooses.

It’s Windy Out There

Almost every day after each of the World Bird Sanctuary Stone Zoo bird shows, one of the staff gets asked how much Norbert our Bald Eagle weighs.

Norbert, the Bald Eagle (photo: Sandra Lowe)

Usually we respond with a question, asking kids and adults how much they think he weighs.  The answers are almost always higher than 20lbs, because most people don’t understand bird anatomy (Norbert weighs just 7 pounds). 

The reason for this faulty weight perception is twofold; the first is something that’s not visible to the naked eye.  Unlike we mammals, birds have hollow bones!  The second reason is one that we can easily see, but usually don’t take into account when doing our weight calculations—feathers!   Feathers are very lightweight—even though there may be several thousand of them on a bird such as an eagle. 

Let’s talk about feathers--that amazing adaptation that gives birds their beauty, insulates them from the heat and cold, and most importantly—allows them to fly.  (Of course, there are some flightless feathered birds, but that’s a discussion for another day.) 

Flight feathers are common to the majority of bird species.  Birds’ feathers will help to catch air, which allows them to stay in flight.  Their wings allow them to direct the air so that they can create lift.  They also will use their wings to flap, soar, and hover, but that depends on what their wings are built for.

Diablo, a Tawny Eagle, has passive soaring wings (photo: Aurora Potts)

There are four different wing shapes.  The first one is Passive soaring wings, which means these birds have long primary feathers (the outermost feathers on the wing).  These long feathers, with slots between each of the outermost five, allow these birds to catch the upward movement of vertical columns of hot air called “thermals” and to fly higher in the sky.  Some examples of these birds are eagles, hawks, and storks.

The second type of wing is the Active soaring wing.  This means that these bird wings are narrow and long, allowing them to soar for long periods of time on horizontal wind currents.  Examples of these birds are gulls, albatrosses, and gannets.

Another type of wing is the Elliptical wing.  These wings are very good for a short burst of high speed flying.  Crows, ravens and sparrows are some examples of birds that have Elliptical wings.

This American Kestrel is a good example of High Speed Wings (photo: Gay Schroer)

The last type of wing is the High speed wing.  The birds in this category have long narrow wings, which allow them to fly very fast for a long period of time.  Swifts, ducks, falcons and sandpipers are some examples of these birds.

As mentioned above, although all these birds are very different, they all have one thing in common... hollow bones, which allow them to be lightweight.  This is a key factor to why birds are able to fly.  Since birds are so lightweight, wind does tend to affect them while they are flying.

Riley the Barn Owl (photo: Aurora Potts)

At WBS’s Stone Zoo bird show in Boston we definitely have windy days that have affected our birds.  For our Barn Owl, Riley, wind can cause him to have to flap harder and longer to fly through the wind to get from one trainer’s glove to another.  Diablo our Tawny Eagle does sometimes get blown off course of his flight pattern on very windy days, but because he’s physically fit from all the practicing we do with him, he always fights through the wind to come back.  Our Red and Green Macaw Rio actually is the exact opposite of my other two examples; she would rather wait for the wind to die down, then fly.

Rio, the Red & Green Macaw (photo: Aurora Potts)

Those windy days can definitely make bird shows very interesting.

Submitted by Taylor Zant, World Bird Sanctuary Stone Zoo Naturalist/Trainer

Birdlore: The Hundred Eyes of the Peacock

The Peacock--almost every child growing up knows this colorful and glamorous bird by sight!  The sapphire glimmering blue body, the long green-yellow and fan-shaped tail display, and the eyed-patterned feathers that peer into your soul…yep, most everyone knows a peacock when they see one.

A Peacock with his feathers spread out in display. (Photo: wikipedia)

 We typically refer to this species as the peacock, since most specimens seen are those with the brilliant blue and green fan-shaped tail display.  In actuality, only the males are called peacocks.  The females are peahens and the chicks are referred to as peachicks.  Together, both males and females are called peafowl.

The blue peafowl (Pavo cristatus) originated in the country of India.  Over hundreds of years, the peafowl have been raised as pets among the royalty in many different cultures and countries.  Even today, peafowl are a popular bird found wandering zoos and farms in the countryside.

Perhaps the most striking feature of a peacock’s feather display is the ‘eye’ resting in the tip of the tail feathers.

The all-seeing ‘eye’ of the peacock.  (Photo: wikipedia)

One origin of the legend of the Peacock’s thousand eyes comes from a story concerning Juno, Queen of the Roman gods, (or Hera of Greek Mythology) and her servant, Argus.

Juno and the king of the gods were famed for fooling and playing tricks on one another.  So, when Juno had the fairest cow in the land, she knew the king would try to steal the cow away from her.  So, she gave the task of watching her cow to her servant, Argus.  He was a giant with a hundred eyes and never had anyone seen all the eyes sleep at the same time.

So, the king, knowing this, sent the smooth talker Mercury to retrieve the cow from the field where Argus guarded over it.  The king had chosen Mercury for this task, since he was a teller of tales and his voice could sing even a god to sleep.

When Mercury came to visit the field, Argus knew what the king was trying to do, but he had been alone with the cow for a long time and wished for the company and entertainment.  So what if a few of his eyes fell asleep.  The remaining awake eyes could still watch the cow.  Argus invited Mercury to tell his stories of the happenings of the world.

As Mercury shared his lively and sad stories, Argus’s eyes closed one by one, until only two remained opened.  Mercury decided then to play his magical reed.  While he played, those listening could hear waves brushing on the shore, the rush of the wind among the trees, lilies tilting their heads at dusk, and stars flickering in the seasonal sky.

Finally, Argus’s two remaining eyes closed in slumber and Mercury whisked away the cream-white cow to the king of the gods.

Juno became greatly angered, as the king had actually managed to play a trick on her and succeeded.  With severe words she berated her servant who could not keep guard over her cow even with a hundred eyes, “Even my peacock is far wiser, for he knows when someone is looking at him.  Every one of your eyes I shall place in the tail of the peacock.”

Today, whenever you look at the feathers of a peacock, you can count the hundred eyes that once belonged to Argus.

Submitted by Jessica Bunke, World Bird Sanctuary Naturalist/Trainer

"Imping" - The Ancient Craft of Feather Replacement

Modern veterinary practices allow the World Bird Sanctuary to do tremendous rehabilitation work and release many of the magnificent birds that come into the hospital back to the wild.  However, on occasion, the best treatment is not necessarily a product of modern veterinary science but a call back to ancient falconry techniques that have been practiced for hundreds of years.

This was recently the case when staff, volunteers, and interns treated a hawk with damaged primary feathers.  The bird was rehabbing well and was becoming strong enough for release.  However, due to previous damage to primary feathers on one wing, the bird's flight capabilities were questionable.  Waiting for natural replacement thru molting would keep the bird in captivity for additional weeks or months.

The solution was the old falconry technique of "imping", a contracted term for "implanting".  Using corresponding feathers from an injured bird of the same species that did not survive attempts at rehabilitation, the damaged feathers with good shafts still in the wing were cut and replaced with new feathers that were spliced and super-glued to the healthy shafts.  The result was a strong wing with good primary feathers, capable of flight and an earlier release.

Under the direction of staff veterans Roger Holloway and Joe Hoffman, WBS staff, interns and volunteers were shown the procedure and then actively participated in imping the replacement of several feathers.

Following are a series of photos showing the procedure.  All photos by Jim Kent.

Choosing the feathers to be implanted

The bird's head is covered to keep him calm during the procedure.

Making sure that the new feather will fit

This bird is well on his way to a new usable wing

Super glue is a wonderful invention

Under close supervision the interns and volunteers got to try their hand at imping

Next stop for this bird--Freedom!

Preliminary assessment is that the imping was successful and that the hawk is well on its way to release.

This is a great example of why WBS has garnered the respect and support of both professional colleagues and our many visitors and supporters.

Perhaps this bird will be someone's "Return to the Wild" bird.  If you would be interested in supporting our wildlife hospital you might like to purchase a "Return to the Wild" event.  To learn more Click Here.

Submitted by Jim Kent, World Bird Sanctuary Wildlife Hospital Volunteer

The Language of Feathers

In the bird world, special coloration of feathers and quality of feathers plays a great role in the choice of mates for breeding purposes. Ornithologists call this process “sexual signaling”.

An English Budgie and a Common Parakeet (photo: Dawn Griffard)

The female bird will make a careful selection of a potential mate by examining the quality of his feathers along with the brightness, iridescence and saturation of their hues.  Female birds are so judgmental because they instinctively want to choose the healthiest male to mate with in order to ensure the continuation of their species.

High quality feathers require a lot of energy and strength to create and maintain. Weak and sickly males cannot afford such flashy feathers, as they must use every ounce of their energy for mere survival.  Therefore, that showy male is the best choice with which to create strong, healthy babies.  However, the cost of such flamboyance is high.  Bright colors and an often long, heavy tail mean that the male is more conspicuous to predators and may have a harder time escaping through flight due to the added weight.

Because of the high cost of these bright colors, some species’ spring molt creates what is called an “alternate plumage”, which allows them to have brighter feathers for just the breeding season.  This can be seen in the bright spring colors of buntings, grosbeaks and wood-warblers.  This spring molt may be just a partial molt which replaces feathers in only certain areas.  This requires much less energy than a complete molt.

While we humans can see many of those gorgeous feather colors that birds can display, some birds can see so much more.  Humans can see only a portion of the electromagnetic spectrum.  The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.  The “visible spectrum” is the portion of the electromagnetic spectrum that is visible to the human eye.  Birds can see the same visible spectrum that we can, but they can also additionally see the ultraviolet spectrum.  The ultraviolet spectrum is invisible to the human eye.  The fact that the ultraviolet light can be seen by birds opens up a whole other world of possible “sexual signaling” coloration.

A photo sowing the fluorescent feathers of a parakeet under a blacklight (photo: Dawn Griffard)

Just like those colors that can be seen in the visible spectrum, colors that can be seen only in the ultraviolet (UV) spectrum can be difficult for the birds to create and maintain.  Therefore, they are also proof of the strength and excellent health of the bird that displays them with gusto.

Recent studies have found that it is mainly parrot species that display these ultraviolet colorations.  Most species of parrot are not sexually dimorphic, which means that males and females have similarly colored feathers.  For example, the northern cardinal is clearly sexually dimorphic – the male bird is bright red, while the female is dull brown/gray with somewhat red wings and tail.  Most parrot species do not have these noticeable differences in coloration.  Perhaps this is why they have the added ability to create the different colors in the UV spectrum in addition to the visible spectrum – to prove their virility.

A male and female Blue Front Amazon Parrot (photo: Dawn Griffard)

In addition to the UV reflective plumage, many of these parrots also have “fluorescing” plumage.  Fluorescent and UV reflective plumage on parrots are often found adjacent to each other and are most often found in body regions associated with active courtship displays.  Although it has not yet been proven, it follows that this coloration is probably also used in sexual signaling for breeding purposes.

Coloration and feather quality is not always the way that males (and sometimes females) prove their worth.  Sometimes it also involves an elaborate song or a complicated dance.  But a beautiful song or dance without a fitting costume is a pale performance.

Submitted by Dawn Trainor Griffard, World Bird Sanctuary Naturalist

May I Have a Feather?

Working for the World Bird Sanctuary with birds of prey and the public, there are many questions that I receive on a daily basis. 

One very important question is, “May I have a feather,” or any variation of such.  Many people are unaware that there is a federal law that protects migratory birds.  Sure, they may know that a license is required to hunt, but it seems to escape the mind that collecting feathers may be illegal without a license.  I will be the first to admit that I was once ignorant of this fact. 

Leigh French, blog author, scolding Jeff Meshach, WBS director, as he tries to "make off" with some Bald Eagle feathers.

The Migratory Bird Treaty Act of 1918 was first enacted in 1916 with Great Britain on behalf of Canada to protect native and migratory birds from over-hunting.  Over time, amendments implemented treaties between the U.S. and Mexico, Japan, and Russia.  This prohibition includes the trading, selling, hunting, and possessing in any way of any bird part without federal licensing.  Federal licenses are granted for religious purposes to American Indian tribes as well as scientific research, education, falconry, taxidermy, and depredation.

During the late 1800’s and early 1900’s the feather trade was at a record high.  Millions of birds were killed each year so that their feathers could adorn women’s hats and other accessories.  Unchecked, the feather trade would have decimated bird populations.  

So, every time I see a beautiful feather, whether it be in the woods or at work, I am reminded of our country’s unfortunate history with animal exploitation and the wonderful way that we can turn things around to save and support our environments and the native animals living within them.

Submitted by Leigh French, World Bird Sanctuary Naturalist/Trainer

Let It Roll Off Your Back

When skies are grey and pouring rain, people will grab their raincoats and umbrellas before going outdoors.

Many wild animals will take cover under trees or in any dry space they can find because, as everyone knows, being out in the cold can be hard to bear, but being soaked to the skin along with being out in the cold is quite a bit worse. 

Blue Penguin, Christchurch NZ - Photo by Gay Schroer

Since this is very true for people and many animals, how come penguins can be seen in the Antarctic, swimming comfortably in the frigid waters, and then hopping out of the water onto the snow as if neither situation is very cold?

How about ducks and geese swimming in a pond on a cold winter’s evening, never seeming to be bothered by the chilling water? 

Tsavo, a Bateleur Eagle, shows off his beautiful head feathers (Photo by WBS volunteer Sandra Lowe Murray)

This is all possible because of the remarkable thing that only birds are lucky enough to posses—feathers!  Feathers have unique qualities that not only allow most birds to fly, but also to keep birds warm/cool and dry when necessary.

Parts of a feather: 1-Vane, 2-Rachis, 3-Barb, 4-Afterfeather, 5-Hollow Shaft, Calamus (Illustration from Wikipedia website) 

An extremely important component of feather waterproofing is the structure of the feathers themselves. The longest and thickest part of a feather is called a rachis.  From the rachis grow the barbs.  These barbs together form the vane or blade of the feather (the softer more pliable section).  Off of the barbs are smaller protrusions referred to as barbules. These are microscopic and have tiny hooks on them that connect the barbules together and by extension, the barbs themselves. When all of the barbules and barbs are hooked together (in a sort of “Velcro” fashion) this creates touch points on the feather that makes the water bead, and keeps water from seeping into the feather itself.

Note how this Barn Owl's feathers overlap, like shingles on a roof

Since bird feathers have the ability to repel water, slightly overlapping feathers across the body makes feathers act like roof shingles so that the water can roll down each feather and then off the bird.  Birds also have a gland at the base of their tails that secretes oil.  Through preening, the oil is spread over all feathers and aids in keeping birds waterproof.

Jet, an American Kestrel can control his body temperature by raising or lowering his feathers (Photo by Gay Schroer)

There is a big difference between uropygial gland oil and fossil fuel oil.  Oil spills will separate the feathers and cause gaps in the arrangement of them.  This allows water and cool/hot temperatures to reach their down feathers (fluffy feathers that generally lie below the contour feathers) and also their skin. In addition to the lack of waterproofing, the oil-covered birds will try to preen (run feathers through their beak) continuously to rid their feathers of the oil.  Not only will the bird swallow oil, constant and non-stop preening is called hyper-preening and can result in permanent feather damage (broken rachises, barbs and barbules).

Oiled Bird (photo from the Wikipedia website)

Some bird species like pigeons and herons have types of feathers called powder down. Instead of molting, powder down feathers continuously grow and the barbs break down into a fine powder which is spread throughout the rest of the feathers.  This powder is believed to help repel water from some bird’s feathers.

Some birds, such as this Great Blue Heron have powder down (Photo by Gay Schroer)

While all of the above tactics aid in keeping water off of a bird’s feathers, Sand Grouse that live primarily in the desert have feathers that capture water.  These feathers are curved and are able to keep water trapped so that, after it bathes in water (which can be miles from its nest), it can then carry the caught water back to its chicks, which drink the water from their parents’ feathers. 

So whether or not they are keeping dry or carrying water with them, something as light as a feather, is heavy with importance for a bird’s survival.

The next time you visit the World Bird Sanctuary be sure to check out the “touch table” display to see just how remarkable a feather truly is.

Submitted by Teresa Aldrich, World Bird Sanctuary Naturalist/Trainer 

Barn Owl Fun Facts: Part 1

 Howdy folks. It’s that time again.  Time for another amazing blog for the WBS blogosphere and today we are going to delve deeper into my favorite subject. You guessed it--The Barn Owl!

You can't see this owl's ears which lie behind all the feathers on the side of its head

Ok, so, I know those who saw my last blog are probably thinking--we’ve all heard the story of Silo; we’ve gone over their amazing hearing and silent flight; everyone knows the owl basics.  However, we’ve never really gotten down to the basics of what really makes a barn owl tick.  So today, we are doing just that.

 The size of an owl's eyes are the equivalent of having two softballs in a human skull

First off, let’s refresh our memories. Barn owls, like all owls, have amazing eyesight. Naturally, hunting at night means they need to be able to see with very little light.  This is also why they need to be able to turn their heads so far around.  Getting the necessary ocular horse power means having very large eyes and having such large eyes means there isn’t enough room left for the muscles needed to rotate the eye in the socket.  Hence, fourteen vertebrae in the neck for maximum head rotation and a 270° field of view when turning their head as far as it will go.

 Minerva displaying only a small example of the amazing head rotation a Barn Owl can achieve

Barn Owls take their amazing senses to the next level over other owls via extreme hearing.  The little Tyto Alba (the genus species name for Barn Owls) is among the most acute listeners in the animal kingdom.  Their facial disks act as a sort of giant ear lobe funneling every little sound into the ear holes on either side of the head.  Factor in offset ear flap placement and they are practically hearing in 3D!  With the audio cortex taking up most of their brain, it is speculated that over the course of its life the Barn owl will learn and remember an infinite number of differences in sounds.  This may seem insignificant to many humans, but this allows Barn Owls to know exactly what kind of animal is scurrying through the grass before the prey ever sees its pursuer.

When asked to close their eyes, these children weren't even aware that this Barn Owl had come within inches of their heads

All right, that covers the senses.  Most owls, including the Barn owl, enjoy “silent flight.”  The softness of the owl feather, or at least the ruffles along the leading and trailing edges of the primary feathers (those large wing feathers furthest away from the body), acts as a sort of muffler, breaking up the air as they fly through and allowing “silent flight.”  Their prey never hears them coming.  A mouse, for example, is just standing there, minding its own business when suddenly, “SILENT FLIGHT!” and it’s viciously grabbed by a hungry Barn owl. 

This is what a mouse would see just before it's grabbed by a hungry Barn Owl

Usually when we think of owls we think nocturnal (active at night), but remember, life is a game of chance and we all seek opportunities where we are most likely to succeed.  In the Barn Owl’s case this means competing with other (in many circumstances larger) raptors (birds of prey).  So we get to use the word of the day: crepuscular.  This is a fancy little word meaning active in twilight.  For the Barn Owl coming out in the darkest part of the night means competing with other owls, making them one of the few species of owl commonly seen hunting at dawn and dusk.

Don't confuse this very light European Barn Owl for a Snowy Owl

Barn owls are also one of the most widespread owl species.  They are found on every continent except Antarctica.  Like any animals found worldwide (humans for instance) Barn owls come in all shapes and sizes.  There are over thirty known sub-species in the family Tytonidae.  The one thing you won’t find, however, is a snowy barn owl; even though Snowy Owls and Barn Owls are often confused for one another.  Barn Owl feathers lack any form of Waterproofing and they don’t put on any of the extra fat necessary for winter survival.

So this lays the groundwork.  We’ve covered the basics and are ready to get to the real meat of the matter.  If you share my love of Barn Owls, you’ll just have to come back for my next blog.

Until next time, keep on traveling.

Submitted by Neal Cowan, World Bird Sanctuary Naturalist

Barn Owl Chick Feathers

Around this time of year, I get a chance to see barn owl chicks up close in the World Bird Sanctuary’s propagation department. 

  Barn Owl chick at 1 week -- at this stage the feather follicles are very visible

Barn Owl chicks hatch with every feature perfectly formed--just on a very small scale.  Their closed eyes are surrounded by the beginnings of little facial discs.  Each foot is covered with impossibly small, yet perfect scales, and each toe is tipped with a sharp little talon.  Along the length of pink, nearly transparent skin covering their bodies, are rows of very active little feather follicles.

Barn Owl chick - 2 weeks old - showing the beginnings of its fluffy white down 

When I first saw a barn owl chick, I was surprised to see that its body was not entirely covered with feathers, as I thought a bird’s body must be.  Instead, it appears that the little bird is wearing a pinstripe suit with pink and white fluffy stripes.  The feather follicles form only along certain regions.  The gaps of bare skin in between the follicles are called apteria.  Birds can raise their feathers to allow air to circulate along the apteria.  This helps the birds keep cool, which is crucial considering that birds have one of the highest metabolic rates of any animal on earth.

  Barn Owl chicks at 3 weeks - covered in its insulating layer of down

When the owlet hatches, it is covered in a fine, natal down.  Soon, this stringy down is replaced with fluffy white down.  The growth of this layer of down is readily visible from day to day, and is nature’s best insulating material.  I wonder if the early down feathers that the young chicks grow resembles the integumentary feathers found on some fossil dinosaur species, such as Sinosauropteryx prima, a small theropod discovered in the Yixian Formation in China.

Barn Owl chicks at 7 weeks - still in down but already beginning to develop its wing feathers  

Could the development of feathers in an individual bird’s life somehow mirror the development of feathers on a much larger time scale?  I don’t know, but when I watch the barn owlets, I see something very primitive, intricate, and beautiful develop right before my eyes.  Every aspect of the owl, from its behavior as an adult education bird, to the development of its first feathers provides me with an endless source for questions and a deep sense of appreciation for the complexity of life on earth.

Submitted by Leah Sainz, World Bird Sanctuary Naturalist/Trainer

Feathers

Feathers distinguish birds from every other animal!

 Clark, one of our team of flying Eagles, using his feathers to brake for a landing

Feathers evolved from scales, and birds still have scales on their legs and feet.  In addition to helping a bird fly, feathers provide insulation and camouflage.

An Upland Sandpiper photographed from a mere 20 feet away - notice how his feathers blend in with the rocks

 Same photo cropped in close to show that there really was a bird there

Feathers are composed of a protein called keratin, the same material that makes up hair and fingernails.  The flight feathers on the wings are called “remiges”, which come from the Latin word for “oarsman”.  The tail feathers on a bird are called “rectrices”, which comes from the Latin word for “helmsman”.

 Photo of Clark showing how he uses his feathers to direct his flight

The feather plumage in adults and juveniles often differ.  For example, juvenile Bald Eagles have brown feathers with white specks.  Around the time the bird turns five years old, the feathers on the head turn completely white (with the majority of eagles) and the feathers on the body turn a more solid brown.

 Photo of Clark as a four-year old still wearing his juvenile plumage

Immature Augur Buzzards have a light brown breast, whereas the adults have a white breast.  Adults have a darker body with white barring on the lower wings, and a red tail.

A young bird’s feathers must grow in all at once.  This requires a great amount of energy, so the feathers are weaker than adult feathers and could wear out more quickly.  However, the first set of feathers will easily get the bird through to it’s first molt, when it slowly replaces all feathers over the next summer.

 Close-up of Harris' Hawk feathers

Juvenile wing feathers are generally more narrow and sharply pointed at the tip than that of adult birds.  Juveniles also have shorter, broader wings than their adult counterparts.  These adaptations sacrifice a little agility, but help the young bird compensate for it’s lack of flying experience:

References:

Trail, Pepper (2001) (PDF), Wing Feathers, U.S. Fish and Wildlife Service, http://www.lab.fws.gov/idnotes/WingFeathers-prnt.pdf

http://www.spiritus-temporis.com/flight-feather/age-differences-in-flight-feathers.html

Submitted by Leah Sainz, World Bird Sanctuary Naturalist