Birds Flashcards
what is their unique feature
feathers
bird characteristics
- General uniformity of structure compared to other taxa • Flight restricts morphological diversity
- Feathers
- Forelimbs modified into wings
- not always used for flight
- Hindlimbs adapted for walking, swimming, or perching
- Keratinized beaks and feathers
- oviparous
Paleognathae
- Large flightless birds
- Ostrich, kiwi
- Flat sternum with poorly developed pectoral muscles
Neognathae
• All other birds
• Nearly all fly
• Penguins are flightless (although they use their wings to ‘fly’
underwater)
• Keeled sternum with powerful flight muscles
what are the adaptations for flight?
- Wings for lift and propulsion
- Bones light yet rigid
- Respiratory system highly efficient
- intense metabolic demands
- Rapid and efficient digestive system
- Energy-rich diet
- High-pressure circulatory system
feather structure (4 parts)
- Shaft: made up of calamus and rachis
- Vanes: soft surfaces of the feather on either side of the rachis
- Barbs: emerge from rachis to form vanes arranged in parallel and spread diagonally outwards.
- Barbules: emerge from each barb and hold the barbs together
Contour feathers
the outermost feathers that give the bird its form
Down feathers
- soft tufts without a prominent rachis
* beneath contour feathers
Filoplumes
- hairlike, degenerate feathers (hairs of a plucked bird)
* Function not known
Powder downs
- Tips disintegrate as they grow releasing a talc-like powder
- Helps to waterproof feathers
- Characteristic of herons, bitterns, hawks and parrots
Remiges
- Flight feathers
- Often largest contour feathers
- Attached by ligaments or directly to the bone
Retrices
- Tail feathers
- Attached to each other by ligaments
- Only innermost are attached to the tailbone
Coverts
- Small feathers that overlay and border reminges and retrices
- Help shape the wing and provide insulation
Molting
- Remiges and retrices are molted in pairs, to maintain balance
- feathers are dead
- plumage can change with molting
- molting takes energy
skeleton
-bones are hollow with air pockets
-skull is fused into one piece
-no teeth
-skeletons of birds and other animals are the same weight. Their weight distribution is different - they have a low center of gravity
-vertebrae are fused
-
Arboreal hypothesis
- Evidence: extant flightless species which can glide • e.g. kakapo, flightless New Zealand parrot
- modifications for lift and powered flight would come later
- Weakness: few feathered dinosaurs were arboreal
Cursorial hypothesis
-less likely
• Evidence: chukar partridge chicks use wingbeats to assist running up steep inclines
• Weakness: difficult to overcome gravity
pneumatized
hollow bones with air cavities
respiration
air sacs
continuous flow
parabronchi = alveoli = gas exchange
