Animals Lec 30-31: Birds Flashcards
(21 cards)
What are the key characteristics of living birds?
Wings and Feathers
Extended Parental Care (K-type)
Beak with no teeth
Large Brain
Internal skeleton
Endothermic with main heat production from metabolism from brown adipose tissue that rich in mitochondria
High Metabolic Rate
explain molting in flight birds
Flight Birds have sequential wing molting from innermost primary feathers outwards
explain molting in flightless birds, why? how does it actually help?
Flightless Birds have simultaneous wing molting - evolutionary catalyst as species with adaptation more suited to surviving on islands without predators
No predators cause ecological release. This causes evolution favours to shift for reduced flight muscles and increased hind limbs.
Saves lots of energy to be flightless as you don’t use much energy to move.
Flight is known to have evolved independently 4x: …
insects, birds, bats, and pterosaurs (bird flight evolution known through fossils.)
Traits for flights in birds:
5 traits
Honeycombed bones - very light and stiff
Feathers shaped into aerodynamic wing (covets and primaries - long feathers to help make wing shape)
Superior power output - big upgrade to oxygen delivery system
Migration (some 11,000 km nonstop)
Fusion of digits in wing to form the shape
4 Key structural characters of flight in birds
Rigidity
Reduction - no teeth, no urinary bladder, only 1 ovary, small gonads only increasing during breeding seasons.
Redistribution
Limb modification
What allows birds to have extreme flight behaviours? (only two)
air sacs - allow unidirection flow and increased metabolic rate. Stor and pump through stationary lungs.
Isocaloric Weight - burn mainly fat for each kilocalorie (0.11g). Allows for very far and long migration
Explain how the Bar-headed goose is able to have extreme flight behaviours:
Bar-Headed Goose - Geese that can fly over the Himalayas - over Everest with ease on their migration
High ventilation rates and breathing patterns allow for more effective gas exchange.
Their high capillaries flight muscles fibers and abundant subscoelmnal mitochondria.
Birds have large hearts, metabolic oxygen utilization and cellular ATP supply, and insensitive cerebral blood vessels to hypercapnia in head (allow for quick pressure changes)
Explain why Atafa/Frigatebirds are able to exhibit extreme flight behaviours:
Atafa/Frigatebird:
Fly for very long times, don’t land, and only eat fish that jump from water.
Fly on the winds in the indian oceans to stay aloft, occasionally catching an updraft to sleep as they fly upwards and fly backdown to feed.
Dynamic souring across the ocean with continual up and down motion of flight perpendicular to the wind currents.
Explain why Red-throated Hummingbirds can exhibit extreme flight behaviours:
Red-throated Hummingbirds:
Fly between Florida and Yucatan peninsula (about 500 miles) and store up 2g of fat out of their 2.5g of total weight to fuel their journey
Every hour, 0.69 kilocalories are burned. If there’s 2g of fat/ 0.11g fat per kilocalorie = 18.18 kilocalories in 2 grams
18.18 kilocalories/0.69 kilocalories in an hour = 26 hours
Hummingbirds travel at a speed of 25 mph, so 25 mph*26 hrs = ~1046 km
With aerodynamic efficiency, hummingbirds can travel up to 900 km (559 miles) on a single gram of fat.
What are Carotenoids? What do they communicate about a bird?
Carotenoids - come from plants, acquired from eating plants or eating something that ate a plant (e.g. insect or zooplankton). This produces reds, oranges, yellows, and greens
If an animal doesn’t eat enough plants or insects, their colors are not very vibrant
What are Melanins? What do they communicate about a bird?
Melanins - Eumelanin and Phaeomelanins
Eumelanin gives grey and black
Phaeomelanins give tan and red
High melatonin contains contents to strengthen feathers. However, it’s expensive to produce.
If a bird is stressed, there’s not enough energy to produce melanins, thus it communicates you don’t have enough energy to mate with.
What are Porphyrins?
Porphyrins - modified amino acids. Fluorescents that are seen in UV lights. Gives pinks, browns, greens, and reds.
What does pigmentation in birds do?
It can communicate to other members of the species how the individual is doing.
Colour can signify dominant .
The pigmentation of feathers and structural differences in feathers give the iridescence.
What is FGF8? what does it do? (do not explain AER or the zone)
Fibroblast growth factor (FGF8) - causes extension of limbs in developing embryos.
Delayed onset of expression in forelimbs causes stunted wings
What is the Apical epidermal Ridge?
Apical epidermal ridge - allows wings to form out into limbs. If you remove the early development part of the limb only the partial limb is formed. Later removal shows more bone structure formed.
part of FGF8
What is the Zone of polarizing activity?
Zone of polarizing activity - a posterior position of limb buds releases Shh hormone, the concentration gradient of this hormone will then form the digits. Worked out by taking one zone and placing it into another.
part of FGF8
What does Shh do?
Sonic Hedgehog (Shh) causes digit formation
Explain the bird phylogeny:
Birds evolved from reptiles, part of the diapsid archosaur clade.
Saurischians evolved into saurischian dinosaurs and birds
Started at Eoraptor dinosaur, first evolving with four digit hands. Closely related (evolved from) Archaeopteryx
Bird phylogeny adapted from downy feathers nad symmetrical contour feathers
Evolved from large dinosaurs and significantly decreased in size to allow for flight.
explain the 7 characteristics of bird:
Wing remodelled version of tetrapod forelimb
Bones have honeycomb air-filled shaft, vanes radiate, made of barbs, with barbules attached
Feathers - consist of a central air-filled shaft. Contour feathers are stiff and have aerodynamic shapes of wing and body. Barbules have hooks that cling to other neighboring bards. When preened, the beak engages the hooks and uniting bards into precise places.
Downy feathers have NO barbs, instead used for insulation
Streamlined body - reduces drag
Powerful flight muscles - pectoral highly developed for flapping
Elongated sternum - provides larger surface for pectoral muscle attachment
Wishbone (furcula) - fused clavicles to support shoulders for flight and flexibility
Explain why rigidity is an important factor in flight in birds:
large keel/carina with muscles attached for flight.
Uncinate processes in ribs with hooks allows ribs not to twist and warp. Thoracic and cervical vertebrae tightly bound together. Fused pelvis, with strong attachment of legs.
Supracoracoideus muscle allows for large flap in wings
