Birds Flashcards
(24 cards)
Characteristics of birds
- wings and feathers
- extended parental care
- external incubation
- beak, no teeth
- large brain
- endothermic
- high metabolic rate
Endothermy in birds
maintained by Adenosine Nucleotide Translocate
- speeding up oxidative phosphorylation and the function of mitochondria to produce heat and no ATP
Avian diversity in NZ
birds fill most ecological niches
mostly flightless due to energetic cost of flying
also in an environment where they could survive without flying
Simultaneous wing molt
almost all feathers will moult at once, or in a very short period of time
- more frequent with less predators, more suited to survive flightlessness
Why fly?
Most expensive = running
Most efficient = swimming
those that fly have adaptations to reduce the cost
Traits for flight in birds
Honey comb bones
Aerodynamic feathers, coverts and primaries to shape wing for flight
superior power outlet, upgrade to O2 delivery system
Avian skeleton
light weight bones
- filled with air
- slender and delicate
- density is higher so strong and stiff
redistribution of mass
4 structural features of birds
Rigidity, reduction, redistribution and limb modifications
Rigidity
- Large Keel for flight muscles
- tightly bound vertebrae
- overlapping ribs so they dont twist during flight
- pelvis is fused
Reduction
- no teeth
- lack urinary bladder
- one overy
- gonad are small, increase in breeding season
Wing shape
depends on the lifestyle of the bird
many rely on wind for flight and less on flapping because it is energy costly
Fibroblast growth factor (FGF8)
causes the extension of limbs in embryos, delayed onset results in flightlessness
Sonic Hedgehog (SHH)
causes digit formation
Air sacs
upregulated respiratory system
- abdominal air sacs, no tidal breathing
- air moves through lungs and air sacs, continual flowing
Example of extreme energy demand
Bar-headed geese flying over the himalyas during migration
- oxygen tension is so low, bird needs enough energy stores to go to higher altitude and down other side
Physiological adaptations of bar-headed geese
larger lungs
higher blood o2 affinity
higher ventilation rates
highly capillarized flight muscles
Frigatebird/Atafa
too heavy to land
reliant on energy wind scapes and follow wind patterns for updrafts, then float back down without much energy cost
Migration fuel
fat is the best fuel, most energy out of burning so many birds put on lots of fat before migrating
Feather pigmentation
can convey info about conditions or dominance
3 types: carotenoids, melanins and porphyrins
Carotenoids
from plants, reds, yellows, oranges, greens
Melanin
eumelanin = greys and blacks
phaeomelanin = tan and red
high melanin content gives strength to feathers, but is expensive to produces
produced in melanocytes
Porphyrins
fluoresce under UV light
modified amino acids
pinks, browns, greens and reds
structural colouration
produced by the way the physical structure interacts with the light, iridescence
Tetrachromatic
birds can see all the colours we see and the UV spectrum
