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