review Flashcards
compare and contrast the wing types, primaries, secondaries and the alula of albatross, sharp tailed grouse and kestrels.
Albatross - high aspect ratio wings - not alot of flapping, soaring high above the sea - secondaries most relevant
Sharp tail - high power but low lift wing - lots of flapping - primaries most relevant
Kestrel- high speed, wing longer than wide(?) - high maneuverability, alula more important
contrast the structure and function of the visual system of the pigeon and the owl
- how does this reflect bone structure
the pigeon has monocular vision - eyes on side of head, wider field of view - makes sense when your a prey animal - need to see whos coming
the owl has binocular vision - eyes on front of head, narrower field of view but better depth perception - predator animals need to accurately judge distance to prey
The following woodpeckers all coexist in the same area. Which do you think do not live in the exact same habitat and why? Downy 35g, Hairy 65g, Red bellied 65g, Red headed 65g, Northern flicker 125g, Pileated 250g
All woodpeckers of different weights could coexist in the exact same habitat according to hutchinsons ratio - 1.3x sixe or 2x weight can coexist with identical ecology and morphology
- they can all exist in the same area due to niche differentiation, so maybe using different parts of the canopy, or go for different prey - otherwise competitive exclusion principle / hybridization
- same size could be active at different times of day
why do birds need uric acid as the base for nitrogenous wastes - what effect does the use of uric acid have on avian water balance
birds have uric acid not urea - urea is heavily diluted, uric acid is very concentrated
- uric acid allows birds to lower weight in water while flying
- highly efficient use of water
Briefly describe the two options suggested for the evolution of birds
thecodont - birds evolved directly from early reptiles before the divergence of dinosaurs
Theropod - birds evolved from a highly derived group of meat eating theropod dinosaurs - archaeopteryx was a theropod - other raptors - also had furcula - same as in modern birds - cladistics in 1980s support this hypothesis
for non waterfowl species which show both breeding and non breeding plumages, describe which feathers are moulted at which times of the year. are these moults usually at the same time as migration or breeding
What are pterylae?
Feather tracts - on most birds (not ostriches or pengiuns) feathers only grow out of specific locations on the bodyy
apterylae are bare patches
Why might a blue or irridescent coloured bird need to moult more frequently?
Blue colour is determined by structure - since feather structured can be degraded by UV or wear, structure and therefore color are lost
- moulting can retain bright blue plumage for breeding
Explain the importance of skeletal modifications in birds
Birds have a reduction in bone number - bones are heavy - no teeth
Reduction in bone weight - pneumaticization - air spaces
Fused bones - helps part to reduce bone number - fusing bones can provide a stronger structure to withstand taking off and landing while still being lightweight
One exception to reduced bone number is in cervical - neck- vertebrae - enables birds that may not be able to move eyes to see all around them
Explain the muscle structure for powered flight? What birds would have a similar down and upstroke?
Birds have large pectoralis for downstroke and reduced supracoracoideus for upstroke
- these may be more similar in hovering birds that flap constantly
What is the nictitating membrane? Pecten?
Functionally a third eyelid that moves horizontally across the eye
- Can protect and retain moisture while flying so eyes dont dry
- can protect underwater for diving birds
- Pecten does something similar within eyeball
Explain bird metabolism and thermoregulation strategies
Birds have the highest metabolism of vertebrates
- birds are endothermic with a high body ttemperature
- metabolic rate is linked to body size - larger birds BMR increases at colder temperatures than smaller birds - BMR can go higher too
- metabolism is higher during the day when birds are active
- Behavioural responses come before an increase in metabolism
Cold weather - start by puffing up - then shiver at cost of energy
Warm weather - find cool spot, dip in bird baths to lose heat thru legs - then evaporative cooling (panting) at cost of energy
birds can also thermoregulate through legs - arteries and veins are paired - warm blood looses heat to cold blood - but also means the arterial blood will loose less heat in the feet as the heat is retained in the venous blood and moved back to body
How do static soaring birds retain a wide surface area of their wings, without being affected by tip vortex?
- tip vortex creates drag but breaking up the tip vortex with slots can reduce the drag
- evident on slotted high lift wings
What kind of birds have high aspect ratio wings? What are some advantages and disadvantages of this?
High wing length and low wing width
- low tip vortex, so low drag and a smooth glider
- little surface area for lift - not good for soaring
- makes sense that this is largely seen in seabirds where there are high winds and waves that provide lift - laysain albatross takes off via dynamic soaring - faster air moves above waves and currents circulate to slower air closer to the water
General steps to speciation
usually starts with geological isolation or some sort of barrier
- divergence in traits due to lack of gene flow
- reproductive isolation occurs
- assortative mating can assist
- how to tell if reproductive isolation has occured if the populations stay seperate?
If a population speciates and achieves reproductive isolation what happens if the populations rejoin?
If the two populations have become seperate species but remained ecologically identical then they cannot coexist because of the competitive exclusion principle
How can a niche be seperated?
- use different habitats in overlapping range - like elevation on a mountain or forest interior vs edge
- use different microhabitats - different layers of canopy
- gathering similar foods in different ways - aerial insectivores vs foragers
- different bill length to access different food stores - shorebirds, woodpeckers
Explain the macarthur and wilson equilibirum model
population model for island geography
- inverse relationship between immigration of new species and the extinction rate
- as the number of species increases, immigration declines and extinction rises
- as the number of species declines, immigration rises and extinction falls
- specific to size of island - larger island can support more species than smaller islands
- specific to island isolation - less isolated islands will have more immigration
Explain species area curves
species area curves describe the relationship between the area of the habitat and the number of species found in that habitat
- we looked at curves showing the correlation between species in a guild and the number of total species
- curves show a strong correlation - in a habitat with few species there are few members of a guild, in habitats with many species you can find many species in that guild
- relationship between number of species that coexist will level off likely due to limit to available niches.
