Birds Flashcards
Characteristics of class Aves
-Adaptations for flight
Wings, feathers
Endothermy
High metabolic rate
Modified vertebral column for flight
Light bones
Horny bill, no teeth
Anatomical similarities of birds to reptiles
Single occipital condyle on skull
Single ear ossicle
Similar lower jaw structure
Physiological similarities of birds to reptiles
Nucleated RBC’s
Similarities in certain aspects of liver and kidney function
Behavioural similarities to reptiles
Nesting and care of young
convincing evidence that supports theropod ancestry hypothesis
-Dinosaur fossils with furcula (wishbone)
-Fusion of clavicles an adaptation for flight in birds
Oldest “bird” discovered
Very close to main line ofevolution between reptilesand birds (transitional forms
Archeopteryx
-long reptilian tail, clawed fingers
Imprints of feathers on tail and wings – evidence that it was a bird
Why is Archeopteryx also important in terms of developing hypotheses on origin of flight
-Wishbone well developed
-May have been a glider or able to fly short distances
-Clawed digits on wings
What is the proposed sequence of evolution of flight:
Jumping branch to branch or branch to ground → gliding → weak flapping to supplement gliding → wing powered flight
What are the two primary functions essential for flight of Feathers?
Provide lift and steering
Prevent excessive heat loss – maintain high metabolic rate
Importance of Feathers
-essential for flight
-roles in courtship, incubation, waterproofing
What are the types of Feathers
-Pennaceous Feathers
-Filoplumes
-Plumulaceous Feathers
-Powder down Feathers
Which type of feather are:
Highly specialized; found on herons, bitterns, hawks, parrots
Tips disintegrate releasing powder for waterproofing
Powder down Feathers
Which type of feather are:
hair-like, degenerate; no known function
Filoplumes
Which type of feather are:
Contour feathers – give bird outward form
Flight feathers - contour feathers that extend beyond body (wings, tail) and used for flight
Pennaceous Feathers
Which type of feather are:
Lack prominent rachis; barbules lack hooks
Hidden beneath contour feathers
Insulation
Abundant on breast and abdomen of water birds
Plumulaceous Feathers
T/F
Molting is orderly process
True, except for penguins
Adaptive features of bird skeleton
-Reduced number of skull bones
-Bill instead of teeth
-Pelvic girdle, vertebral column and ribs strengthened for flight
T/F
Largest and strongest muscles are flight muscles
True
Process of Flight
-Bird wings form air foil
-Upper surface slightly convex / lower surface slightly concave
-Air passing over travels farther and faster than air passing under
-Air pressure on upper surface decreases and lift is created
-Forward thrust is produced during downstroke of wing
-Slotted feathers at wing tips or presence of alula reduce turbulence
Process of Flapping Flight
-Downstroke:
Outer wing moves down, slightly forward and rotates lower edge is below trailing edge
-Upstroke:
Wing folds slightly and returns to original position with minimum drag
How hummingbirds have unique wing structure
Wing is nearly rigid but hinged at shoulder by swivel joint and powered by enlarged supracoracoideus muscle
Hovering – wing moves in sculling motion
Provides lift without propulsion on both forward and backstroke
How bird’s stomach modified into two regions
-Proventriculus – secretes gastric juices
-Ventriculus (gizzard) – with muscular wall to crush, abrade seeds, nuts etc.
Birds eliminates food through?
cloaca
Birds also use a _____________ system but also have a special mechanism that allows one-way flow over gas exchange surfaces
negative pressure system
