Zoology Final c Flashcards
unique characteristic of birds
- feathers
- evolved from reptilian scales
- makes possible their greatest adaptation - flight
structure of feathers
- barbs arise from main feather shaft
- each barb has its own shaft from which the barbules arise
which feathers are responsible for birds ability to fly?
- remiges
- primaries
- secondaries
remiges feathers
feathers on the wings
primary feathers
provide forward propulsion to move the bird through the air
- asymmetrical vanes: the leading vane is relatively narrower than the trailing vane, so that the primary twists as it is pulled downward, acting like propeller
secondary feathers
provide lift to keep the bird in the air
- wing is curved in cross-section so that air travels relatively faster over the top of the wing
- the faster air travels, the less pressure it exerts on a service
- Bernoulli effect
high speed wings
- longer than wide, taper
- no wing slots
broad, rounded wings
- good maneuverability
- low speed flight
soaring and gliding wings
- much longer than wide
- high speed
long, slotted wings
- terrestrial soaring birds
- can carry heavy loads
characteristics of tail feathers
- rectrices
- symmetrical
- responsible for braking, maneuverability and also provide lift
characteristics of down feathers
- have barbules that do not interlock
- evolved for purpose of insulation; preceded flight feather, since warm-blooded animals need to be insulated to keep heat in
what muscle is responsible for downstroke of birds wing and where does it attach
- pectoralis and attaches on the ventral humerus from the keel
what muscle is responsible for the upstroke of birds wing and where does it attach
- supracoracoideus and attaches on the dorsal humerus from the keel
what adaptations are found in feet of perching birds
mechanism by which toes auto magically tighten around perch when they land on it, enabling them to perch with minimum of muscular effort
respiratory system in birds
one way flow of sir through lung increase efficiency
one-way flow of air
- air from trachea bypasses lungs and enters the posterior air sacs
- air passes from posterior air sacs through lungs to anterior air sacs
- air passes from anterior air sacs back out of trachea
flight adaptations
- air sac system reduces eight of bird which increase power/weight ratio
- reduced weigh tof skeleton without reducing its power by extending air sacs through hollow, pneumatic bones reinforced by struts
- birds have relatively large heart
- sexual organs atrophy during non-breeding season, and only left ovary develops during breeding season
- homiothermic which allows for higher metabolic rate
homiothermic
warm-blooded
brain of the bird
- cerebral cortex
- hyperstriatum
- cerebellum
cerebral cortex
poorly developed, and is not associated with higher behavioral processes as it is in mammal
hyperstriatum
higher behavioral processes are centered here
- not found in mammals
cerebellum
relatively large in birds, need for extreme muscular coordination
- smarter behavior
bird vision
- extremely good visual acuity, due to much greater density of cone cells in fovea of retina
- fovea is region of keenest vision
- some birds have two fovea to focus in two places simultaneously
hawks and eagle vision
- have telescopic eyes to magnify objects
- visual acuity of hawk is 8 times that of human, enabling it to see food more than a mile away
reproduction in birds
- an extremely efficient digestive system allows nestlings to leave nest as soon as possible
- two types of young: altricial and precocial
altricial young
- born blind, naked and helpless
precocial young
- born fully-feathered and mobile
bird migration
- experimental evidence has shown that the sun, stars and earth’s magnetic field are all involved, depending on the species
- undertake very long migrations
neotropical migrants
- 170000 sq km of tropical rainfoest is lost a year
- tropical rainforest is home to neotropical birds
- includes those of songbirds
- forest fragmentation
how many birds are killed my cats a year
19 million
forest fragmentation
- split forests into sections
- causes increased predation because predators hunt on the borders and when split into different sections that results in more borders
cowbird parasitism
- brown-headed cowbird lay eggs in other birds nest, since cowbirds are bigger, they get fed over songbirds which causes the songbirds to die
what very important fossil is very strong evidence of relationship between birds and reptiles?
- Archeopteryx
- reptilian skeleton, but with true feathers
