Feathers & Plumages Flashcards
Add labels to the following diagram of a feather:
What are all feather structures made of?
Keratin, a proteinaceous connective tissue (the same basic material of human fingernails)
What is a feather follicle?
A feather follicle is a small, epidermis-lined pit in the skin of a bird from which a feather grows and to which it remains attached.
What’s the difference between the pennaceous and plumulaceous portion of a feather?
Pennaceous describes the portion of the vane that is relatively flat and has a defined shape.
Plumulaceous describes the portion of the vane for which the loose, fluffy barbs are not structured into flat vanes.
In one sentence, describe how feathers are formed.
A feather emerges from a feather follicle like a thin-walled straw that becomes unfurled along its long axis, and its branched structure is created by the intricate fusing of fine fibres.
What is meant by ‘dorsal’ and ‘ventral’ feather surfaces?
The dorsal feather surface is the top surface of the feather while the ventral feather surface is the bottom surface of the feather.
So, for example, in flight, the dorsal surface would be facing the sky, while the ventral surface would be facing the ground.
What is meant by the ‘proximal’ and ‘distal’ ends of the feather?
The proximal end of the feather is the portion nearest to the feather follicle (bird’s body), while the distal end is distant to the feather follicle.
What are pin feathers?
Pin feathers are developing feathers that look like oddly thick, plastic rods enclosed within a bluish or greyish waxy covering called a sheath.
What is the function of the sheath on developing feathers (or pin feathers)?
The sheath protects the nascent feather as it grows. It then dries and dies, splitting and falling away (or is preened away by the bird).
What are fault bars and why do they sometimes develop?
Fault bars are transverse regions on a mature feather with slightly different colouring or texture that correspond to different stressful days of feather growth. For example, short-term periods of extreme nutritional deficiencies.
Often these fault bars are most apparent in the tail feathers.
True or false?
Feathers evolved from reptilian scales.
False.
Although feathers have some features in common with the reptilian scale, the columnar nature of the feather follicle itself is a unique feature. Thus, developmentally, from the creation of the follicle forward, all of the details of feather growth are novel and have no direct parallels to other animals.
Which other living creatures have feathers?
Birds are the only living creatures that have feathers, making them quite unique!
How do we know that some theropod dinosaurs had “proto-feathers”?
Numerous non-avian theropod fossils have been found with clear imprints of integumentary appendages surrounding the body, like pigmented halos around fossilized limbs, torsos, heads, necks, and tails.
Additionally, these appendages were found to have been made from beta-keratin, which is known only to occur in bird feathers and reptile scales.
Since we know most feathered dinosaurs could not fly, what was the purpose of the variety of feather forms seen across many theropod lineages?
It is unclear what the original function of ancient and, later, modern feathers were for dinosaurs but they seem to have diversified rapidly to serve many functions, such as protective covering, social advertising, and camouflage.
The aerodynamic or flight function of feathers only evolved later, closer in time to the evolutionary radiation of birds themselves.
What’s the difference between pterylae and apteria?
Pterylae are feather tracts—the areas of a bird’s skin to which feathers are attached—whereas apteria are regions of bare or less-feathered skin between the feather tracts.
What is the pterylosis of a bird?
The pterylosis is the detailed arrangement of feather tracts and bare patches across the body of a bird.
The pterylosis varies among groups of birds. For example, waterbirds such as penguins have a continuous pterylosis, presumably to help prevent water from penetrating to the bird’s skin and chilling it.
What are the two basic physical environments a bird’s feathers interact with?
A bird’s feathers encounter fluid media (in the form of air and water) and electromagnetic radiation (in the form of heat and light).
What are the SIX main groupings of feathers?
- Downy feathers: fluffy undercoat for insulation;
- Contour feathers: covers the torso and acts as a sunscreen, windbreaker, and raincoat;
- Strong pennaceous wing and tail feathers for flight;
- Semiplumes: insulation around the edges
- Ventless bristles around the mouth for feeding functions;
- Filoplumes: ornamental feathers for signalling to potential mates or rivals
What are down feathers and what function do they serve?
Down feathers are entirely plumulaceous, soft, and fluffy feathers that typically lack a rachis. They function as lightweight, but high-quality insulation.
Downy feathers are especially important for small birds living in cold climates, as well as for birds that float on, dive into, or swim in water.
What are precocial birds?
Precocial birds are already well-feathered with down when they hatch. They also have substantial powers of thermoregulation and locomotion, making them far more independent and able to feed themselves.
For example: the domestic chicken, many species of ducks and geese, waders, rails, and the hoatzin.
What are altricial birds?
Altricial birds are hatched relatively undeveloped and, in many cases, naked or with sparse down; such helpless young require complete parental care.
For example: Robins and most songbirds, woodpeckers, and herons**.
What’s the difference between natal down and body down?
Natal down are the feathers that cover the body of a hatchling bird, whereas body down are the feathers that lie under the contour feathers in many adult birds.
Penguins, loons, petrels, auks, geese, and ducks have these feathers for thermal insulation.
What bird is known for its incredibly soft and warm down feathers, which are used in the manufacture of clothing and bedding?
The Common Eider
Think: eider down duvets! Female ducks (and other waterfowl) actually pluck their own feathers and use them to line their nests to keep their hatchlings warm.
What are contour feathers?
Covering most of the surface of an adult bird, contour feathers give a bird its characteristic shape or outline.
The plumulaceous proximal end provides insulation while the pennaceous distal end provides a barrier against the elements (think of overlapping roof shingles).
What function do contour feathers serve?
Contour feathers form an effective barrier against sunlight, wind, and rain, while also helping to insulate and streamline the body (during flight or swimming).
How do most feathers manage to be effectively water repellent?
Water beads on the surface of most feathers due to air spaces (and trapped air) between the barbs and barbules.
Additionally, the uropygial gland at the base of their tail excretes oils that birds use to maintain and waterproof their feathers.
If most feathers repel water effectively, why do birds like cormorants and anhingas have to dry their wings by spreading them in the sun?
Cormorants and anhingas actually have feathers that are relatively easy to wet, which helps them to dive under water without the buoyant effect of trapped air bubbles. This makes them faster swimmers, but requires them to dry off by sunning themselves after feeding.
How do contour feathers remain organized on a bird’s body, without becoming dishevelled?
Tension in a set of tiny muscles attached to the contour feathers keeps them positioned correctly.
These muscles also allow the bird to move its feathers voluntarily, not individually, but in one mass movement of either raising (fluffing) or lowering (sleeking) them.
Give some examples of modified contour feathers.
The crest feathers of the Palm Cockatoo (Australia); the straw-like crown feathers of the Black-Crowned Crane (Africa); the long, elegant plumes of many herons and egrets; the fancy plumes, breast plates, and capes of many birds-of-paradise are all modified contour feathers.
What percentage of a bird’s total weight does its feathers typically account for?
Although the feathers of some birds seem to make up half of their volume, the feather coat commonly accounts for only 5-10% of a bird’s total weight.
What are flight feathers?
Flight feathers are long, strong pennaceous feathers that make up the majority of the wing and tail surfaces of birds.
What are remiges and rectrices?
Remiges are the flight feathers of the wing;
Rectrices are the flight feathers of the tail.
