Lab 6 Flashcards
(55 cards)
Bird flight adaptations
Digits greatly reduced/lost
Feathers
Pygostyle
Flight is powered mainly by breast muscles
Keeled sternum
Pneumatized bones
Digits greatly reduced/lost
Only digits 1 through 3 contribute to wing skeleton
Feathers
Make up bulk of wing and tail
Pygostyle
Bones of tail reduced and modified
Keeled sternum
Concentration of muscle placed on keeled sternum keeps center of gravity low and aligned with wings
Pneumatized bones
The hollow structure of bird’s bones help to lighten the skeleton
Wing basic structures
Alula
Primary wing slotting
Alula
The first digits of a bird’s wing bears the alula
When spread away from the rest of the wing and angled the alula created a wing slot that redirect air over the upper surface of the wing
This prevents stalling when the main airfoil of the wing is pointing upward
Primary wing slotting
The primary feathers of some birds have a distinct constriction near the tips
When spread out, they create wing slots which reduce drag created by vortices at the wing tips
Aspect ratio
Simply the ratio between the length and width of the wing
A long narrow wing will have a high aspect ratio
Camber
The ventral concavity of the wings surface
Wing types
Elliptical
High speed
High aspect ratio
High lift
Elliptical wings
Wings with a low aspect ratio
Typical of birds that inhabit dense environments such as forests
Elliptical wings maximize surface area and lift
Enables a high degree of maneuverability in a compact form
High speed wings
Wings with a medium/high aspect ratio and very low camber
Maximize thrust and have a reduced surface area and camber making it easier to rapidly beat the wing
High aspect ratio wings
Excellent air foils (like plane wings) but stay at low speeds
Long distance birds
Rely on consistent strong winds to increase the air speed moving over the wing enabling the bird to stay aloft by angling the wing upward
High lift wings
Wings with a medium aspect ratio, high camber and obvious primary wing slotting
Maximize lift generated with each wing beat or from upward moving air currents
Soaring types
Static soaring
Dynamic soaring
Static soaring
static soarers keep aloft by seeking out air currents that rise vertically as a result of hot air rising or of deflection off a large obstruction
Fly in a circle above the rising current
Will glide between pillars of rising air to glide
Dynamic soaring
Angle their wings upward in opposition to horizontally directed wind currents to quickly gain altitude
Once high enough, the bird will glide downward in the direction of their choosing
When altitude becomes low, the bird will again direct itself into the wind, repeating the cycle as before
Have high aspect ratio wings
Bird skull features
Modified diapsid
Cranial kinesis
Loss of teeth
Keratinized beak
Modified diapside
Reduction and loss of temporal bars associated with reduced bite-force and increased flexibility compared to other archosaurs
Cranial kinesis
The skulls of most birds are highly kinetic
Loss of teeth
Often cited as a weight reducing adaptation
Keratinized beak
Much lighter than teeth
Food acquisition and processing
