Birds Flashcards
What class are birds in?
Aves.
What did birds evolve from?
Theropod dinosaurs.
When did true birds appear?
Cretaceous.
When did birds diversify?
Tertiary.
What are the two major bird clades?
Paleognathae and neognathae.
Give characteristics of Paleognathae.
No keel, flightless.
e.g. ostrich.
Give characteristics of Neognathae.
Flexible palate.
Possess carina/sternal keel.
Includes penguins.
What are the three main foot formations in passeriformes?
Anisodactyly - 3 forward, 1 back.
Zygodactyly - X shape.
Pamprodactyly - 4 forward.
What skull fenestration do birds have?
Diapsid.
What is a gizzard?
Muscular structure used to grind up and process food. Sometimes filled with pebbles birds eat to mechanically grind up food.
What is a toucan bill like?
Biocomposite beak, interior is rigid foam composed of bony fibres and the exterior is made of keratin.
What is a woodpecker bill like?
Spongy bone at the site of impact between the beak and skull as a cushion. Longer lower parts of mandibles direct force away from the brain.
Are birds ovi, ovovivi or viviparous?
Oviparous.
How can birds conserve heat?
Draw beak and feet into plumage.
Counter-current heat exchange, arteries going in and veins going out in close proximity recapture heat and save it.
Torpor or hibernation.
What is a bird’s circulatory system like?
4-chambered heart.
Larger body size:heart mass ratio compared to mammals.
What is a bird’s respiratory system like?
Unidirectional airflow.
Compare bird and reptile senses.
Reduction in smell in birds.
Expansion in optic lobes. - provide larger and sharper images.
Expansion of forebrain. .
Describe avian vision.
3 eyelids.
4 photoreceptors (tetrachromatic vision).
Can see UV colours.
Describe magnetic vision.
Magnetic sense dependent on light. Avian compass arises in the protein cryptochrome, found in rod cells of retina.
Describe avian hearing.
Has 3 sections, outer ear, middle and inner ear.
Nocturnal birds of prey use hearing, diurnal ones use vision.
Owls has asymmetric ear openings and a facial mask to guide sounds into their ears.
What do birds use echolocation for?
Navigation in dark.
How did the forelimb become the wing?
Humerus, radius and ulna similar.
Carpals fuse.
Digits reduce.
Primaries on hand, secondaries on arm.
How did the pectoral girdle adapt?
- Wings above centre of gravity.
- Sternum forms keel from which flight muscles attach.
- Clavicle fused to form wishbone.
- Wishbone prevents collapse of girdle mid-flight.
What are the major flight muscles?
Pectoralis - pulls wing down (large).
Supracoracoideus - pulls wing up.
What are skeletal adaptations of birds?
Vertebral column becomes fused and rigid.
Ligaments become ossified.
Lumbar vertebrae form synsacrum.
Increased cervical vertebrae for flexible neck.
Caudal vertebrae form pygostyle (tail feathers).
What is flapping flight?
Propulsion from primaries.
Lift from secondaries.
Drag reduction from alula, coverts and rectrices.
What are causes of drag?
Frictional drag from air resistance.
Induced drag from formation of vortices at wingtips when airflow is separated from airfoil.
How do birds minimise drag?
Streamlining (no external ears, feet tucked in, feather and wing shape).
Tails spread at low speeds, become furled with increasing speed.
Fly in wake of other birds.
How do you calculate aspect ratio?
Wing length / wing width.
How do you calculate wing loading?
Mass / wing area.
What are down feathers?
Loosely structured feathers beneath contours which help trap air near body for warmth.
What are semiplumes?
Loose and fluffy feathers provide insulation and increase water bird buoyancy.
What are filoplumes?
Small hair-like feathers with a few barbs at the top, occur among contours.
What are bristle feathers?
Vaneless contours with a few barbs at base, around eyes, nostrils and mouth.
What are powder down feathers?
Continuously growing and are never moulted, disintegrate into powder.
What are contours?
Form outer covering of bird, includes primaries, secondaries and tail feathers.
What is migration?
2-way movement between breeding and wintering areas. Usually based on season and driven by availability of food. More frequent in Northern Hemisphere.
What are the dangers of migration?
Possible competition changes. Energy expenditure. Predation. Collision. Hazardous journey, unknown new habitats? Timing. Endurance performance. Navigation.
What are the sex chromosomes of birds?
ZW for female, WW for male.
What does precocial mean?
Needs less parental care.
What does altricial mean?
Needs more parental care.
What is polygyny?
A male bird breeds with >1 female.
What is polyandry?
When a female bird abandons her eggs to breed with more than one male.
What is lekking?
Cluster of males attack females, males provide nothing but sperm.
