Chapter 4 - Feathers Flashcards
Functions of feathers
. Insulation for regulation of body temperature.
* Aerodynamic power for flight.
* Colors for communication and camouflage.
* Modified feathers may also used for swimming,
sound production, hearing, protection, water
repellency, tactile sensation, etc.
Structure of feathers
Feathers are made of B-keratin, which is a
fibrous protein polymer with strong
mechanical properties.
* The same protein, B-keratin, is also found
in the beaks, claws, and leg scales of
birds.
Structure of Pennaceous Feathers
The vane consists of barbs, which are parallel,
lateral branches of the rachis.
* Each barb consists of a main ramus, which has
many smaller structures, barbules, projecting
from both the proximal and distal surfaces of the
ramus.
* Barbules that project from the proximal surface
of the ramus have a ridge for locking. Barbules
that project from the distal surface of the ramus
have hooks, also known as barbicels.
The hooked barbules from the distal surface of
one barb will hook around the barbules from the
proximal surface of the adjacent barb.
* In this way, the barbs and barbules interlock, like
Velcro, to form the flat but flexible structure of a
pennaceous vane.
Modifications of Vane Structure
In waxwings, the barbs near the distal ends of
some feathers are fused into a wax-like structure
that provides bright coloration
In the Desert Sandgrouse, the
barbules are coiled in a way that
allows them to hold on to extra
water. This species transports
water to its nestlings by dipping its
belly in water and then carrying it
to the nest.
Modifications of Vane Structure In Cormorants and anhingas
In cormorants and anhingas, the loss of
barbicels actually makes the feathers absorb
more water, which helps to reduce buoyancy
during diving. However, these feathers require a
long air drying time.
Modifications of Vane Structure in rails and ducks
the barbs are large and
close together, and the barbicels are extra
long and curved. This causes the feathers
to be more water-repellent.
King Rail
Structure of Plumulaceous Feathers
The loose vanes of
plumulaceous feathers
do have barbs, and
those barbs have
barbules. However, the
barbules do not have
hooks, so they do not
interlock with barbules
on adjacent barbs.
Aftershaft
The contour, or body,
feathers of some bird
have a secondary
structure called an
aftershaft. An aftershaft
consist of another
rachis and vane
attached to the same
calamus.
* Main function is to
enhance insulation.
Flight Feathers
The flight feathers include feathers of the wings (remiges
– provided lift and thrust) and feathers of the tail
(rectrices – used for steering and braking).
* Long, pennaceous feathers designed for aerodynamic
forces during flight.
* Coverts cover the bases of these feathers.
Undertail Coverts
Remiges
divided into primaries and
secondaries. The primaries attach to the bones
of the hand, while the secondaries attach to the
ulna.
The leading edges of remiges are narrow than
the trailing edges; this limits vibrations of the
leading edge.
* This effect is more pronounced on primaries
than on secondaries.
Owl Flight feathers
The rectrices on the feathers of owls have a
modified leading edge. The distal barbs on the
leading edge have very long tips called
pennulae. These create a fuzzy edge on the
surface of the vane that reduces air turbulence
and vibration while in flight. This allows the owls
to have a more silent flight.
American Woodcock flight feathers
Male American Woodcocks due a ritual display
flight to attract mates. Males will spiral upward
into the sky while his wings make twittering
sound produced by air passing through three
narrow outer primaries.
Duck Flight feathers
In many ducks, the secondaries form a
prominent colorful patch called the
speculum.
In the Mandarin Duck, the secondaries are
erected during courtship displays.
What are the rectrices attached to
The rectrices are attached to the
pygostyle.
Tail feathers can be modified in various
ways.
Woodpeckers, Wilsons Snipe, Courtship
