Birds Flashcards
Where is it believed birds evolved from?
Theropod dinosaurs
In which era were birds being assembled?
Early Cretaceous
What is the Archaeopteryx?
Transitional organism between feathered dinosaurs and modern birds, emerged in the late Jurrasic, between 148-155 million years ago
Name the Archaeopteryx’s bird-like features
1) Long spindly legs
2) Long neck
3) Small head and large eyes
4) Pubic bone rotated
5) Fused clavicles
6) Outwards arm rotation
7) Modern flight/contour feathers
Name the Archaeopteryx’s reptile-like features
1) Clawed hands
2) Long thin and bony tail
3) Teeth
4) Small sternum
5) Solid bone structure
Describe the Confuciusornithidae
Moe bird-like than Archeopteryx, it had hollow bones, a toothless beak, clawed wings and a shortened tail
What are vestigial wing claws?
Small bony protrusions on the wings that aid in gripping branches. They still exist today in spur-winged plovers and hoatzin chicks
What is the name given to ‘early true birds’? And what did they have that modern birds don’t?
Euornithes. Teeth
Moas and Elephant birds belong to which super-order?
Paleognathae
Which super-order is most speciose?
Neoaves
To which super order do ducks, geese and swans belong?
Galloanserae
Name the 5 feather-types and what they are for
Filoplume - displays Flight - flying Bristle - sensing Down - insulation Semiplume
Describe the structure of a feather
The calamus (tip) extends upwards and fanning off both sides is a vane composed of barbs and barbules. The rachis gives the feather mechanical support across its entire length.
Feathers take a lot of effort to maintain. Name the activities performed by bird species in order to maintain their feathers.
1) Preening with oil from a preen gland
2) Bathing in water
3) Dust bathing
4) Anting
What else can feathers do?
They can provide camouflage through cypsis and also visual and acoustic displays in birds of paradise.
How do birds maintain their body temperatures?
1) Complete homiothermy
2) Strategic hypothermia
3) Torpor
4) Hibernation
Why is it beneficial for an organism to fly?
Avoid predators Hunt Reach safe nesting sites Extends home-range size Display flights
How do wings enable flight?
They have an aerofoil shape, meaning air takes longer to travel over the wing rather than under, which generates lift. Increasing the angle of attack increases lift but reduces forward momentum. The downstroke increases pressure on the wing underside, generating more lift during a wing flap. The wing is partially folded and flexed on the upstroke to reduce drag, although hummingbirds achieve lift on both the upstroke and downstroke.
Describe one evolution of flight model
Trees-down model; (gliding) swooping down to catch prey from a vantage point, it could explain why Archaeopteryx was poorly adapted for flapping but had asymmetrical aerodynamic feathers. However foot morphology suggests proto-birds did not climb trees.
OR
Ground-up model; It takes a swan to run to 12km/h before it can take off, but protobirds couldn’t run that fast. Maybe they used their wings for wing-assisted incline running or wing assisted water walking.
What is an irruptive migration?
Migration that isn’t tied to seasons (although there is correlation)
What is a fovea and why do some bird species have more than one?
An area of clear visual acuity. 54% of birds of prey have two fovea for advanced sidewards viewing, and greater field of acuity
Why do birds retinas contain many photoreceptor cells?
They contain folded membranes layered with visual pigments to trap light from a narrow angle
How to birds have better resolution than us?
Larger eyes (image spread over more photoreceptors)
Tighter packing of the photoreceptors
Increasing cone:rod ratio
How do birds have better sensitivity than us?
Bigger pupils
Increasing cone:rod ratio
