Birds Flashcards
What are the 2 major groups of birds?
The palaeognathae and the neognathae
How many species of bird are there?
Approx. 10,000
What is the palaeognathae composed of?
The ratites and the tinamiformes
The ratites are large and flightless. How is this shown in their skeleton.
They have no keel on their sternum.
What is the neognathae composed of?
The gallon serae and the neoaves.
What are the gallon serae?
Ducks and jungle fowl.
Which group contains 95% of bird diversity?
The neoaves
Archaeopteryx was the first bird sample. What features were theropod and which are avian?
Theropod = long pubis, caudal tail, teeth in the beak, claws
Avian = furculum, 3 digits, feathers
How many digits do birds have?
3
What is the pygostyle?
Fused caudal vertebrae for flight muscles and feather attachment.
What does the furculum do?
Strengthens the thoracic skeleton. It also stores energy on the downstroke of the wing which is released on the upstroke.
What is the syncosacrum?
The pelvis is fused to the vertebrae for stability in landing.
Why is a digigrade stance advantageous to birds?
It shifts their centre of gravity backwards.
What is the rachis?
The ventral, hollow vein in a feather.
What are the main types of feather?
Insulation, flight, contour and display.
Why are flight feathers asymmetrical?
So the flight vector does not flip the feather over on the downstroke.
What is unique about birds’ eyes?
They are so large that they dorso-laterally compress the brain and meet in the centre of the head.
What shape are birds’ eyes?
Tubular
Which digit supports the wing?
3
What is the alula and what does it do?
Digit 2, stops the wings stalling at high angles of attack.
What is characteristic about birds hovering?
They extend their hand skeletons.
What do birds that fly long distances need?
A lift to drag ratio, essentially a high speed to low energy.
Are the flight muscles proximal or distal?
Proximal
What do the barbules do?
Hook together to ensure a continuous flight surface.
How many vertebrae are fused into the synsacrum?
12-20
What are the 2 main flight muscles?
Pectoralis and supracoracoideus
What is the pectoralis and where does it insert?
The depressor (pulls the wing down), inserts underneath the humerus
What is the supracoracoideus and where does it insert?
The elevator (pulls the wing up) and inserts into the upper humerus
What is characteristic about birds’ bones?
They’re hollow
Why are birds’ skull strong?
The bones are fused so there are no sucha lines
Why do birds have complex stomachs?
Because they have no oral processing
There are 2 major parts to the stomach - what do they both do?
- The proventrichus = produces acid and enzymes for chemical digestion
- The gizzard = mechanical digestion
What is the crop?
An organ that stores food for regurgitation
Birds reduce their aortic arches but which one do they retain?
The right systemic arch
Why is one artery so efficient?
Creates a higher blood pressure with less resistance to accommodate high metabolism
What kind of lungs do birds have?
Faveolar lungs
Why are birds’ lungs different to mammals’?
They use through-flow as opposed to tidal flow.
How many air sacs are there and where are they?
9, throughout the body and bones
How birds’ lungs work?
Air is inhaled, most of it flows into the air sacs. The air in the lungs undergoes gaseous exchange and is exhaled, then the air from the air sacs flows into the lungs.
Why are birds’ lungs so efficient?
They constantly have fresh air in.
Why is gaseous exchange so efficient in birds?
There is a cross-current exchange between the blood and the air.
How is breathing controlled?
Expansion/contraction of the flight muscles.
Birds are ectothermic. How high is their body temperature?
Between 40-42 degrees
Why are birds only ever ovivaporous?
Because carrying eggs/young within the body would make flight impossible.
What is the precocial development strategy?
The young hatch as mini adults and are fully independent
What is the altricial development strategy?
The young hatch as helpful, fully dependant chicks
