BIRD FEATHER EXPLORATION

Introduction: In the following activity you will explore the anatomy of a bird feather and types of bird feathers.

Part 1 - Feathers in Birds:

Birds have many unique features! They are bipedal, meaning they walk on two legs. They are endotherms that create their own body heat as a product of their metabolism. They lay amniotic eggs with a shell. They have wings that many species use for flight. They have a sharp beak that lacks teeth. Instead of teeth, their digestive tract contains a gizzard, a muscular organ often filled with stones to grind up food. All these features can be found amongst other animals outside of class Aves, though! In the spaces below, list one or two examples of non-avian vertebrates that share these features with birds. If needed, use the internet.

Now challenge yourself to think of a living non-bird animal that has feathers. Can you think of one? I’ll save you some time … you can’t! Birds are the only living animals that have feathers!

What are feathers?

Feathers are made of keratin, the same protein that hair, fingernails, and reptile scales are made of. Just like your hair grows from a hair follicle, feathers grow from feather follicles! Feather follicles form in the skin of a bird when it is still in its egg. Initially, a feather begins as a small, tube-like structure called a pin feather or a "blood feather" because it has a blood supply. These early feathers poke out from the follicle and look like a feather shaft. As the feather matures, it pushes out further from the follicle, the blood supply recedes, and the cells making up the feather die. The feather shaft elongates, and the barbs and barbules, the feathery branches and hooks on the feather, start to develop from the shaft.

Birds use their feathers for a variety of functions. Feathers enable flight, providing lift and propulsion as birds navigate the air. They also aid in thermoregulation, insulating birds against extreme temperatures by trapping air close to the body. Additionally, feathers serve as waterproofing agents, preventing water from reaching a bird's skin and allowing them to remain buoyant and dry during activities such as swimming or diving. Feathers also play roles in communication and camouflage, with some species using vibrant plumage for attracting mates or intimidating rivals, while others utilize strategic coloration to blend into their surroundings and evade predators.

Checkpoint:

1.   Why are feathers considered the only distinguishing feature of birds?

2.   What are feathers made of? ____________________________________________________________

3.   What other structures amongst animals are made of this protein?

4.   Where do feathers grow from in birds? ___________________________________________________

5.   What is the initial structure of a developing feather called? ___________________________________

6.   Why are developing feathers sometimes referred to as "blood feathers"?

7.   What happens to the blood supply as a feather matures?

8.   What are barbs and barbules in a mature feather?

9.   What are the 5 functions of feathers in birds? You can use bullet points to answer this question.

Part 2 - Anatomy of a Feather:

Feathers are composed of several distinct parts, each serving a specific function. Not all feathers have all parts.

Rachis: also known as the shaft; the central part of the feather that runs base to tip; provides support

Barbs: the main branches that extend from the shaft

Vane: the flat, smooth part of the feather that consists of the barbs interlocking together; most feathers have 2 vanes

Barbules: microscopic, hair-like structures that project from each barb; interlock with other barbules to hold the barbs together like a zipper

Calamus: also known as the quill; the hollow, barbless base of the feather that attaches to the bird’s skin

Plumulaceous region: area on the feather where the barbs do not interlock and appear soft and fluffy

Checkpoint:

1.   Label the rachis, barbs, vane, plumulaceous region, and calamus of the feather below.

2.   Why can’t you label the barbules on the feather in the picture above?

3.   In the chart below, record which part of a feather each statement is describing. Parts of the feather can be used more than once.

4.   Birds preen their feathers, or care for them and clean them, when the barbules become disturbed and

no longer interlock with each other. If a bird did not preen their feathers and return the barbs and barbules to their interlocking positions, what consequences would there be? Hint: Base your answer on thefunctions thatfeathers serve!

Part 3 - Types of Feathers:

Birds have multiple types of feathers depending upon their habitat, flight, mating habits, and more. Feathers are split into two main types: vaned feathers and down feathers.

The feather that you labeled on page 3 of this activity is a vaned feather. Vaned feathers are visible on the exterior of a bird's body and are used for flight, waterproofing, attracting mates, and more. Vaned feathers are flat, stiff, and smooth. Vaned feathers typically have two vanes, one on either side of the rachis. The barbs of vaned feathers are tightly interlocked by barbules.

Vaned feathers include flight feathers, which make up the wings and tail of a bird. Flight feathers are long, broad, stiff, and often asymmetrical. Flight feathers often lack a plumulaceous region and play little role in insulation.

Vaned feathers also include contour feathers, which cover the body of a bird like shingles. Contour feathers are symmetrical. They have a vaned visible region and a soft plumulaceous region at the base. The vaned portion of each contour feather can be colorful, plain, or matched to the environment for camouflage. The plumulaceous region of a contour feather serves to trap heat around the body of a bird.

Down feathers are soft, fluffy, lightweight, and beneath the vaned feathers. They provide insulation of heat. Birds that live in cold climates, such as ducks, geese, and penguins, tend to have more down feathers. Down feathers typically lack a rachis and vanes. They are exclusively plumulaceous, with barbs that tangle together instead of interlocking, providing an insulating layer above the skin.

Checkpoint:

1.   What are three differences between vaned feathers and down feathers?

2.   What are two types of vaned feathers? ___________________________________________________

3.   In the chart below, record which type of feather each statement is describing. Types of feathers can be

used more than once. Choose from flight, contour, and down feathers.

4.   Is “feather A” a flight feather, contour feather, or down feather. Provide two reasons to support your answer.

5.   Is “feather B” a flight feather, contour feather, or down feather. Provide two reasons to support your answer.

6.   Is “feather C” a flight feather, contour feather, or down feather. Provide two reasons to support your answer.

Part 4 - Observation of Feathers:

Your teacher will provide you with two feathers. Using the naked eye, a magnifying glass, and even a microscope, observe each feather. Record your observations in the section below.

Feather #1

1.   Draw the first feather in the space below. Label the rachis, vanes, barbs, calamus, and plumulaceous region. Depending upon the type of feather, some of these structures will not be present.

2.   Is the feather plumulaceous, vaned, or both? ______________________________________________

3.   Is the feather symmetrical or asymmetrical? _______________________________________________

4.   Does the feather have a rachis? If so, describe the rachis.

5.   Are the barbs of the feather tightly interlocked or loosely tangled?

6.   Based on your observations, is this feather a flight, contour, or down feather? ____________________

7.   Based upon your answer to the previous question, what purpose did this feather likely serve in the bird?

8.   If available, observe the feather under a microscope. Attempt to view the rachis and barbs. In your drawing, label the rachis, barbs, and barbules (if visible and present).

Feather #2

1.   Draw the first feather in the space below. Label the rachis, vane, barbs, calamus, and plumulaceous

region. Depending upon the type of feather, some of these structures will not be present.

2.   Is the feather plumulaceous, vaned, or both? ______________________________________________

3.   Is the feather symmetrical or asymmetrical? _______________________________________________

4.   Does the feather have a rachis? If so, describe the rachis.

5.   Are the barbs of the feather tightly interlocked or loosely tangled?

6.   Based on your observations, is this feather a flight, contour, or down feather? ____________________

7.   Based upon your answer to the previous question, what purpose did this feather likely serve in the bird?

8.   If available, observe the feather under a microscope. Attempt to view the rachis and barbs. In your drawing, label the rachis, barbs, and barbules (if visible and present).